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Diffstat (limited to 'libjava/classpath/java/util/prefs/AbstractPreferences.java')
| -rw-r--r-- | libjava/classpath/java/util/prefs/AbstractPreferences.java | 1272 |
1 files changed, 1272 insertions, 0 deletions
diff --git a/libjava/classpath/java/util/prefs/AbstractPreferences.java b/libjava/classpath/java/util/prefs/AbstractPreferences.java new file mode 100644 index 00000000000..3f70400f5d1 --- /dev/null +++ b/libjava/classpath/java/util/prefs/AbstractPreferences.java @@ -0,0 +1,1272 @@ +/* AbstractPreferences -- Partial implementation of a Preference node + Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.util.prefs; + +import gnu.java.util.prefs.NodeWriter; + +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.OutputStream; +import java.util.HashMap; +import java.util.Iterator; +import java.util.TreeSet; + +/** + * Partial implementation of a Preference node. + * + * @since 1.4 + * @author Mark Wielaard (mark@klomp.org) + */ +public abstract class AbstractPreferences extends Preferences { + + // protected fields + + /** + * Object used to lock this preference node. Any thread only locks nodes + * downwards when it has the lock on the current node. No method should + * synchronize on the lock of any of its parent nodes while holding the + * lock on the current node. + */ + protected final Object lock = new Object(); + + /** + * Set to true in the contructor if the node did not exist in the backing + * store when this preference node object was created. Should be set in + * the contructor of a subclass. Defaults to false. Used to fire node + * changed events. + */ + protected boolean newNode = false; + + // private fields + + /** + * The parent preferences node or null when this is the root node. + */ + private final AbstractPreferences parent; + + /** + * The name of this node. + * Only when this is a root node (parent == null) the name is empty. + * It has a maximum of 80 characters and cannot contain any '/' characters. + */ + private final String name; + + /** True when this node has been remove, false otherwise. */ + private boolean removed = false; + + /** + * Holds all the child names and nodes of this node that have been + * accessed by earlier <code>getChild()</code> or <code>childSpi()</code> + * invocations and that have not been removed. + */ + private HashMap childCache = new HashMap(); + + // constructor + + /** + * Creates a new AbstractPreferences node with the given parent and name. + * + * @param parent the parent of this node or null when this is the root node + * @param name the name of this node, can not be null, only 80 characters + * maximum, must be empty when parent is null and cannot + * contain any '/' characters + * @exception IllegalArgumentException when name is null, greater then 80 + * characters, not the empty string but parent is null or + * contains a '/' character + */ + protected AbstractPreferences(AbstractPreferences parent, String name) { + if ( (name == null) // name should be given + || (name.length() > MAX_NAME_LENGTH) // 80 characters max + || (parent == null && name.length() != 0) // root has no name + || (parent != null && name.length() == 0) // all other nodes do + || (name.indexOf('/') != -1)) // must not contain '/' + throw new IllegalArgumentException("Illegal name argument '" + + name + + "' (parent is " + + (parent == null ? "" : "not ") + + "null)"); + this.parent = parent; + this.name = name; + } + + // identification methods + + /** + * Returns the absolute path name of this preference node. + * The absolute path name of a node is the path name of its parent node + * plus a '/' plus its own name. If the node is the root node and has no + * parent then its path name is "" and its absolute path name is "/". + */ + public String absolutePath() { + if (parent == null) + return "/"; + else + return parent.path() + '/' + name; + } + + /** + * Private helper method for absolutePath. Returns the empty string for a + * root node and otherwise the parentPath of its parent plus a '/'. + */ + private String path() { + if (parent == null) + return ""; + else + return parent.path() + '/' + name; + } + + /** + * Returns true if this node comes from the user preferences tree, false + * if it comes from the system preferences tree. + */ + public boolean isUserNode() { + AbstractPreferences root = this; + while (root.parent != null) + root = root.parent; + return root == Preferences.userRoot(); + } + + /** + * Returns the name of this preferences node. The name of the node cannot + * be null, can be mostly 80 characters and cannot contain any '/' + * characters. The root node has as name "". + */ + public String name() { + return name; + } + + /** + * Returns the String given by + * <code> + * (isUserNode() ? "User":"System") + " Preference Node: " + absolutePath() + * </code> + */ + public String toString() { + return (isUserNode() ? "User":"System") + + " Preference Node: " + + absolutePath(); + } + + /** + * Returns all known unremoved children of this node. + * + * @return All known unremoved children of this node + */ + protected final AbstractPreferences[] cachedChildren() + { + return (AbstractPreferences[]) childCache.values().toArray(); + } + + /** + * Returns all the direct sub nodes of this preferences node. + * Needs access to the backing store to give a meaningfull answer. + * <p> + * This implementation locks this node, checks if the node has not yet + * been removed and throws an <code>IllegalStateException</code> when it + * has been. Then it creates a new <code>TreeSet</code> and adds any + * already cached child nodes names. To get any uncached names it calls + * <code>childrenNamesSpi()</code> and adds the result to the set. Finally + * it calls <code>toArray()</code> on the created set. When the call to + * <code>childrenNamesSpi</code> thows an <code>BackingStoreException</code> + * this method will not catch that exception but propagate the exception + * to the caller. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException when this node has been removed + */ + public String[] childrenNames() throws BackingStoreException { + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + TreeSet childrenNames = new TreeSet(); + + // First get all cached node names + childrenNames.addAll(childCache.keySet()); + + // Then add any others + String names[] = childrenNamesSpi(); + for (int i = 0; i < names.length; i++) { + childrenNames.add(names[i]); + } + + // And return the array of names + String[] children = new String[childrenNames.size()]; + childrenNames.toArray(children); + return children; + + } + } + + /** + * Returns a sub node of this preferences node if the given path is + * relative (does not start with a '/') or a sub node of the root + * if the path is absolute (does start with a '/'). + * <p> + * This method first locks this node and checks if the node has not been + * removed, if it has been removed it throws an exception. Then if the + * path is relative (does not start with a '/') it checks if the path is + * legal (does not end with a '/' and has no consecutive '/' characters). + * Then it recursively gets a name from the path, gets the child node + * from the child-cache of this node or calls the <code>childSpi()</code> + * method to create a new child sub node. This is done recursively on the + * newly created sub node with the rest of the path till the path is empty. + * If the path is absolute (starts with a '/') the lock on this node is + * droped and this method is called on the root of the preferences tree + * with as argument the complete path minus the first '/'. + * + * @exception IllegalStateException if this node has been removed + * @exception IllegalArgumentException if the path contains two or more + * consecutive '/' characters, ends with a '/' charactor and is not the + * string "/" (indicating the root node) or any name on the path is more + * then 80 characters long + */ + public Preferences node(String path) { + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + // Is it a relative path? + if (!path.startsWith("/")) { + + // Check if it is a valid path + if (path.indexOf("//") != -1 || path.endsWith("/")) + throw new IllegalArgumentException(path); + + return getNode(path); + } + } + + // path started with a '/' so it is absolute + // we drop the lock and start from the root (omitting the first '/') + Preferences root = isUserNode() ? userRoot() : systemRoot(); + return root.node(path.substring(1)); + + } + + /** + * Private helper method for <code>node()</code>. Called with this node + * locked. Returns this node when path is the empty string, if it is not + * empty the next node name is taken from the path (all chars till the + * next '/' or end of path string) and the node is either taken from the + * child-cache of this node or the <code>childSpi()</code> method is called + * on this node with the name as argument. Then this method is called + * recursively on the just constructed child node with the rest of the + * path. + * + * @param path should not end with a '/' character and should not contain + * consecutive '/' characters + * @exception IllegalArgumentException if path begins with a name that is + * larger then 80 characters. + */ + private Preferences getNode(String path) { + // if mark is dom then goto end + + // Empty String "" indicates this node + if (path.length() == 0) + return this; + + // Calculate child name and rest of path + String childName; + String childPath; + int nextSlash = path.indexOf('/'); + if (nextSlash == -1) { + childName = path; + childPath = ""; + } else { + childName = path.substring(0, nextSlash); + childPath = path.substring(nextSlash+1); + } + + // Get the child node + AbstractPreferences child; + child = (AbstractPreferences)childCache.get(childName); + if (child == null) { + + if (childName.length() > MAX_NAME_LENGTH) + throw new IllegalArgumentException(childName); + + // Not in childCache yet so create a new sub node + child = childSpi(childName); + // XXX - check if node is new + childCache.put(childName, child); + } + + // Lock the child and go down + synchronized(child.lock) { + return child.getNode(childPath); + } + } + + /** + * Returns true if the node that the path points to exists in memory or + * in the backing store. Otherwise it returns false or an exception is + * thrown. When this node is removed the only valid parameter is the + * empty string (indicating this node), the return value in that case + * will be false. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException if this node has been removed + * and the path is not the empty string (indicating this node) + * @exception IllegalArgumentException if the path contains two or more + * consecutive '/' characters, ends with a '/' charactor and is not the + * string "/" (indicating the root node) or any name on the path is more + * then 80 characters long + */ + public boolean nodeExists(String path) throws BackingStoreException { + synchronized(lock) { + if (isRemoved() && path.length() != 0) + throw new IllegalStateException("Node removed"); + + // Is it a relative path? + if (!path.startsWith("/")) { + + // Check if it is a valid path + if (path.indexOf("//") != -1 || path.endsWith("/")) + throw new IllegalArgumentException(path); + + return existsNode(path); + } + } + + // path started with a '/' so it is absolute + // we drop the lock and start from the root (omitting the first '/') + Preferences root = isUserNode() ? userRoot() : systemRoot(); + return root.nodeExists(path.substring(1)); + + } + + private boolean existsNode(String path) throws BackingStoreException { + + // Empty String "" indicates this node + if (path.length() == 0) + return(!isRemoved()); + + // Calculate child name and rest of path + String childName; + String childPath; + int nextSlash = path.indexOf('/'); + if (nextSlash == -1) { + childName = path; + childPath = ""; + } else { + childName = path.substring(0, nextSlash); + childPath = path.substring(nextSlash+1); + } + + // Get the child node + AbstractPreferences child; + child = (AbstractPreferences)childCache.get(childName); + if (child == null) { + + if (childName.length() > MAX_NAME_LENGTH) + throw new IllegalArgumentException(childName); + + // Not in childCache yet so create a new sub node + child = getChild(childName); + + if (child == null) + return false; + + childCache.put(childName, child); + } + + // Lock the child and go down + synchronized(child.lock) { + return child.existsNode(childPath); + } + } + + /** + * Returns the child sub node if it exists in the backing store or null + * if it does not exist. Called (indirectly) by <code>nodeExists()</code> + * when a child node name can not be found in the cache. + * <p> + * Gets the lock on this node, calls <code>childrenNamesSpi()</code> to + * get an array of all (possibly uncached) children and compares the + * given name with the names in the array. If the name is found in the + * array <code>childSpi()</code> is called to get an instance, otherwise + * null is returned. + * + * @exception BackingStoreException when the backing store cannot be + * reached + */ + protected AbstractPreferences getChild(String name) + throws BackingStoreException + { + synchronized(lock) { + // Get all the names (not yet in the cache) + String[] names = childrenNamesSpi(); + for (int i=0; i < names.length; i++) + if (name.equals(names[i])) + return childSpi(name); + + // No child with that name found + return null; + } + } + + /** + * Returns true if this node has been removed with the + * <code>removeNode()</code> method, false otherwise. + * <p> + * Gets the lock on this node and then returns a boolean field set by + * <code>removeNode</code> methods. + */ + protected boolean isRemoved() { + synchronized(lock) { + return removed; + } + } + + /** + * Returns the parent preferences node of this node or null if this is + * the root of the preferences tree. + * <p> + * Gets the lock on this node, checks that the node has not been removed + * and returns the parent given to the constructor. + * + * @exception IllegalStateException if this node has been removed + */ + public Preferences parent() { + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + return parent; + } + } + + // export methods + + /** + * XXX + */ + public void exportNode(OutputStream os) + throws BackingStoreException, + IOException + { + NodeWriter nodeWriter = new NodeWriter(this, os); + nodeWriter.writePrefs(); + } + + /** + * XXX + */ + public void exportSubtree(OutputStream os) + throws BackingStoreException, + IOException + { + NodeWriter nodeWriter = new NodeWriter(this, os); + nodeWriter.writePrefsTree(); + } + + // preference entry manipulation methods + + /** + * Returns an (possibly empty) array with all the keys of the preference + * entries of this node. + * <p> + * This method locks this node and checks if the node has not been + * removed, if it has been removed it throws an exception, then it returns + * the result of calling <code>keysSpi()</code>. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException if this node has been removed + */ + public String[] keys() throws BackingStoreException { + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + return keysSpi(); + } + } + + + /** + * Returns the value associated with the key in this preferences node. If + * the default value of the key cannot be found in the preferences node + * entries or something goes wrong with the backing store the supplied + * default value is returned. + * <p> + * Checks that key is not null and not larger then 80 characters, + * locks this node, and checks that the node has not been removed. + * Then it calls <code>keySpi()</code> and returns + * the result of that method or the given default value if it returned + * null or throwed an exception. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public String get(String key, String defaultVal) { + if (key.length() > MAX_KEY_LENGTH) + throw new IllegalArgumentException(key); + + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + String value; + try { + value = getSpi(key); + } catch (ThreadDeath death) { + throw death; + } catch (Throwable t) { + value = null; + } + + if (value != null) { + return value; + } else { + return defaultVal; + } + } + } + + /** + * Convenience method for getting the given entry as a boolean. + * When the string representation of the requested entry is either + * "true" or "false" (ignoring case) then that value is returned, + * otherwise the given default boolean value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public boolean getBoolean(String key, boolean defaultVal) { + String value = get(key, null); + + if ("true".equalsIgnoreCase(value)) + return true; + + if ("false".equalsIgnoreCase(value)) + return false; + + return defaultVal; + } + + /** + * Convenience method for getting the given entry as a byte array. + * When the string representation of the requested entry is a valid + * Base64 encoded string (without any other characters, such as newlines) + * then the decoded Base64 string is returned as byte array, + * otherwise the given default byte array value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public byte[] getByteArray(String key, byte[] defaultVal) { + String value = get(key, null); + + byte[] b = null; + if (value != null) { + b = decode64(value); + } + + if (b != null) + return b; + else + return defaultVal; + } + + /** + * Helper method for decoding a Base64 string as an byte array. + * Returns null on encoding error. This method does not allow any other + * characters present in the string then the 65 special base64 chars. + */ + private static byte[] decode64(String s) { + ByteArrayOutputStream bs = new ByteArrayOutputStream((s.length()/4)*3); + char[] c = new char[s.length()]; + s.getChars(0, s.length(), c, 0); + + // Convert from base64 chars + int endchar = -1; + for(int j = 0; j < c.length && endchar == -1; j++) { + if (c[j] >= 'A' && c[j] <= 'Z') { + c[j] -= 'A'; + } else if (c[j] >= 'a' && c[j] <= 'z') { + c[j] = (char) (c[j] + 26 - 'a'); + } else if (c[j] >= '0' && c[j] <= '9') { + c[j] = (char) (c[j] + 52 - '0'); + } else if (c[j] == '+') { + c[j] = 62; + } else if (c[j] == '/') { + c[j] = 63; + } else if (c[j] == '=') { + endchar = j; + } else { + return null; // encoding exception + } + } + + int remaining = endchar == -1 ? c.length : endchar; + int i = 0; + while (remaining > 0) { + // Four input chars (6 bits) are decoded as three bytes as + // 000000 001111 111122 222222 + + byte b0 = (byte) (c[i] << 2); + if (remaining >= 2) { + b0 += (c[i+1] & 0x30) >> 4; + } + bs.write(b0); + + if (remaining >= 3) { + byte b1 = (byte) ((c[i+1] & 0x0F) << 4); + b1 += (byte) ((c[i+2] & 0x3C) >> 2); + bs.write(b1); + } + + if (remaining >= 4) { + byte b2 = (byte) ((c[i+2] & 0x03) << 6); + b2 += c[i+3]; + bs.write(b2); + } + + i += 4; + remaining -= 4; + } + + return bs.toByteArray(); + } + + /** + * Convenience method for getting the given entry as a double. + * When the string representation of the requested entry can be decoded + * with <code>Double.parseDouble()</code> then that double is returned, + * otherwise the given default double value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public double getDouble(String key, double defaultVal) { + String value = get(key, null); + + if (value != null) { + try { + return Double.parseDouble(value); + } catch (NumberFormatException nfe) { /* ignore */ } + } + + return defaultVal; + } + + /** + * Convenience method for getting the given entry as a float. + * When the string representation of the requested entry can be decoded + * with <code>Float.parseFloat()</code> then that float is returned, + * otherwise the given default float value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public float getFloat(String key, float defaultVal) { + String value = get(key, null); + + if (value != null) { + try { + return Float.parseFloat(value); + } catch (NumberFormatException nfe) { /* ignore */ } + } + + return defaultVal; + } + + /** + * Convenience method for getting the given entry as an integer. + * When the string representation of the requested entry can be decoded + * with <code>Integer.parseInt()</code> then that integer is returned, + * otherwise the given default integer value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public int getInt(String key, int defaultVal) { + String value = get(key, null); + + if (value != null) { + try { + return Integer.parseInt(value); + } catch (NumberFormatException nfe) { /* ignore */ } + } + + return defaultVal; + } + + /** + * Convenience method for getting the given entry as a long. + * When the string representation of the requested entry can be decoded + * with <code>Long.parseLong()</code> then that long is returned, + * otherwise the given default long value is returned. + * + * @exception IllegalArgumentException if key is larger then 80 characters + * @exception IllegalStateException if this node has been removed + * @exception NullPointerException if key is null + */ + public long getLong(String key, long defaultVal) { + String value = get(key, null); + + if (value != null) { + try { + return Long.parseLong(value); + } catch (NumberFormatException nfe) { /* ignore */ } + } + + return defaultVal; + } + + /** + * Sets the value of the given preferences entry for this node. + * Key and value cannot be null, the key cannot exceed 80 characters + * and the value cannot exceed 8192 characters. + * <p> + * The result will be immediatly visible in this VM, but may not be + * immediatly written to the backing store. + * <p> + * Checks that key and value are valid, locks this node, and checks that + * the node has not been removed. Then it calls <code>putSpi()</code>. + * + * @exception NullPointerException if either key or value are null + * @exception IllegalArgumentException if either key or value are to large + * @exception IllegalStateException when this node has been removed + */ + public void put(String key, String value) { + if (key.length() > MAX_KEY_LENGTH + || value.length() > MAX_VALUE_LENGTH) + throw new IllegalArgumentException("key (" + + key.length() + ")" + + " or value (" + + value.length() + ")" + + " to large"); + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + putSpi(key, value); + + // XXX - fire events + } + + } + + /** + * Convenience method for setting the given entry as a boolean. + * The boolean is converted with <code>Boolean.toString(value)</code> + * and then stored in the preference entry as that string. + * + * @exception NullPointerException if key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void putBoolean(String key, boolean value) { + put(key, String.valueOf(value)); + // XXX - Use when using 1.4 compatible Boolean + // put(key, Boolean.toString(value)); + } + + /** + * Convenience method for setting the given entry as an array of bytes. + * The byte array is converted to a Base64 encoded string + * and then stored in the preference entry as that string. + * <p> + * Note that a byte array encoded as a Base64 string will be about 1.3 + * times larger then the original length of the byte array, which means + * that the byte array may not be larger about 6 KB. + * + * @exception NullPointerException if either key or value are null + * @exception IllegalArgumentException if either key or value are to large + * @exception IllegalStateException when this node has been removed + */ + public void putByteArray(String key, byte[] value) { + put(key, encode64(value)); + } + + /** + * Helper method for encoding an array of bytes as a Base64 String. + */ + private static String encode64(byte[] b) { + StringBuffer sb = new StringBuffer((b.length/3)*4); + + int i = 0; + int remaining = b.length; + char c[] = new char[4]; + while (remaining > 0) { + // Three input bytes are encoded as four chars (6 bits) as + // 00000011 11112222 22333333 + + c[0] = (char) ((b[i] & 0xFC) >> 2); + c[1] = (char) ((b[i] & 0x03) << 4); + if (remaining >= 2) { + c[1] += (char) ((b[i+1] & 0xF0) >> 4); + c[2] = (char) ((b[i+1] & 0x0F) << 2); + if (remaining >= 3) { + c[2] += (char) ((b[i+2] & 0xC0) >> 6); + c[3] = (char) (b[i+2] & 0x3F); + } else { + c[3] = 64; + } + } else { + c[2] = 64; + c[3] = 64; + } + + // Convert to base64 chars + for(int j = 0; j < 4; j++) { + if (c[j] < 26) { + c[j] += 'A'; + } else if (c[j] < 52) { + c[j] = (char) (c[j] - 26 + 'a'); + } else if (c[j] < 62) { + c[j] = (char) (c[j] - 52 + '0'); + } else if (c[j] == 62) { + c[j] = '+'; + } else if (c[j] == 63) { + c[j] = '/'; + } else { + c[j] = '='; + } + } + + sb.append(c); + i += 3; + remaining -= 3; + } + + return sb.toString(); + } + + /** + * Convenience method for setting the given entry as a double. + * The double is converted with <code>Double.toString(double)</code> + * and then stored in the preference entry as that string. + * + * @exception NullPointerException if the key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void putDouble(String key, double value) { + put(key, Double.toString(value)); + } + + /** + * Convenience method for setting the given entry as a float. + * The float is converted with <code>Float.toString(float)</code> + * and then stored in the preference entry as that string. + * + * @exception NullPointerException if the key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void putFloat(String key, float value) { + put(key, Float.toString(value)); + } + + /** + * Convenience method for setting the given entry as an integer. + * The integer is converted with <code>Integer.toString(int)</code> + * and then stored in the preference entry as that string. + * + * @exception NullPointerException if the key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void putInt(String key, int value) { + put(key, Integer.toString(value)); + } + + /** + * Convenience method for setting the given entry as a long. + * The long is converted with <code>Long.toString(long)</code> + * and then stored in the preference entry as that string. + * + * @exception NullPointerException if the key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void putLong(String key, long value) { + put(key, Long.toString(value)); + } + + /** + * Removes the preferences entry from this preferences node. + * <p> + * The result will be immediatly visible in this VM, but may not be + * immediatly written to the backing store. + * <p> + * This implementation checks that the key is not larger then 80 + * characters, gets the lock of this node, checks that the node has + * not been removed and calls <code>removeSpi</code> with the given key. + * + * @exception NullPointerException if the key is null + * @exception IllegalArgumentException if the key length is to large + * @exception IllegalStateException when this node has been removed + */ + public void remove(String key) { + if (key.length() > MAX_KEY_LENGTH) + throw new IllegalArgumentException(key); + + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node removed"); + + removeSpi(key); + } + } + + /** + * Removes all entries from this preferences node. May need access to the + * backing store to get and clear all entries. + * <p> + * The result will be immediatly visible in this VM, but may not be + * immediatly written to the backing store. + * <p> + * This implementation locks this node, checks that the node has not been + * removed and calls <code>keys()</code> to get a complete array of keys + * for this node. For every key found <code>removeSpi()</code> is called. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException if this node has been removed + */ + public void clear() throws BackingStoreException { + synchronized(lock) { + if (isRemoved()) + throw new IllegalStateException("Node Removed"); + + String[] keys = keys(); + for (int i = 0; i < keys.length; i++) { + removeSpi(keys[i]); + } + } + } + + /** + * Writes all preference changes on this and any subnode that have not + * yet been written to the backing store. This has no effect on the + * preference entries in this VM, but it makes sure that all changes + * are visible to other programs (other VMs might need to call the + * <code>sync()</code> method to actually see the changes to the backing + * store. + * <p> + * Locks this node, calls the <code>flushSpi()</code> method, gets all + * the (cached - already existing in this VM) subnodes and then calls + * <code>flushSpi()</code> on every subnode with this node unlocked and + * only that particular subnode locked. + * + * @exception BackingStoreException when the backing store cannot be + * reached + */ + public void flush() throws BackingStoreException { + flushNode(false); + } + + /** + * Writes and reads all preference changes to and from this and any + * subnodes. This makes sure that all local changes are written to the + * backing store and that all changes to the backing store are visible + * in this preference node (and all subnodes). + * <p> + * Checks that this node is not removed, locks this node, calls the + * <code>syncSpi()</code> method, gets all the subnodes and then calls + * <code>syncSpi()</code> on every subnode with this node unlocked and + * only that particular subnode locked. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException if this node has been removed + */ + public void sync() throws BackingStoreException { + flushNode(true); + } + + + /** + * Private helper method that locks this node and calls either + * <code>flushSpi()</code> if <code>sync</code> is false, or + * <code>flushSpi()</code> if <code>sync</code> is true. Then it gets all + * the currently cached subnodes. For every subnode it calls this method + * recursively with this node no longer locked. + * <p> + * Called by either <code>flush()</code> or <code>sync()</code> + */ + private void flushNode(boolean sync) throws BackingStoreException { + String[] keys = null; + synchronized(lock) { + if (sync) { + syncSpi(); + } else { + flushSpi(); + } + keys = (String[]) childCache.keySet().toArray(new String[]{}); + } + + if (keys != null) { + for (int i = 0; i < keys.length; i++) { + // Have to lock this node again to access the childCache + AbstractPreferences subNode; + synchronized(this) { + subNode = (AbstractPreferences) childCache.get(keys[i]); + } + + // The child could already have been removed from the cache + if (subNode != null) { + subNode.flushNode(sync); + } + } + } + } + + /** + * Removes this and all subnodes from the backing store and clears all + * entries. After removal this instance will not be useable (except for + * a few methods that don't throw a <code>InvalidStateException</code>), + * even when a new node with the same path name is created this instance + * will not be usable again. + * <p> + * Checks that this is not a root node. If not it locks the parent node, + * then locks this node and checks that the node has not yet been removed. + * Then it makes sure that all subnodes of this node are in the child cache, + * by calling <code>childSpi()</code> on any children not yet in the cache. + * Then for all children it locks the subnode and removes it. After all + * subnodes have been purged the child cache is cleared, this nodes removed + * flag is set and any listeners are called. Finally this node is removed + * from the child cache of the parent node. + * + * @exception BackingStoreException when the backing store cannot be + * reached + * @exception IllegalStateException if this node has already been removed + * @exception UnsupportedOperationException if this is a root node + */ + public void removeNode() throws BackingStoreException { + // Check if it is a root node + if (parent == null) + throw new UnsupportedOperationException("Cannot remove root node"); + + synchronized(parent) { + synchronized(this) { + if (isRemoved()) + throw new IllegalStateException("Node Removed"); + + purge(); + } + parent.childCache.remove(name); + } + } + + /** + * Private helper method used to completely remove this node. + * Called by <code>removeNode</code> with the parent node and this node + * locked. + * <p> + * Makes sure that all subnodes of this node are in the child cache, + * by calling <code>childSpi()</code> on any children not yet in the + * cache. Then for all children it locks the subnode and calls this method + * on that node. After all subnodes have been purged the child cache is + * cleared, this nodes removed flag is set and any listeners are called. + */ + private void purge() throws BackingStoreException + { + // Make sure all children have an AbstractPreferences node in cache + String children[] = childrenNamesSpi(); + for (int i = 0; i < children.length; i++) { + if (childCache.get(children[i]) == null) + childCache.put(children[i], childSpi(children[i])); + } + + // purge all children + Iterator i = childCache.values().iterator(); + while (i.hasNext()) { + AbstractPreferences node = (AbstractPreferences) i.next(); + synchronized(node) { + node.purge(); + } + } + + // Cache is empty now + childCache.clear(); + + // remove this node + removeNodeSpi(); + removed = true; + + // XXX - check for listeners + } + + // listener methods + + /** + * XXX + */ + public void addNodeChangeListener(NodeChangeListener listener) { + // XXX + } + + public void addPreferenceChangeListener(PreferenceChangeListener listener) { + // XXX + } + + public void removeNodeChangeListener(NodeChangeListener listener) { + // XXX + } + + public void removePreferenceChangeListener + (PreferenceChangeListener listener) + { + // XXX + } + + // abstract spi methods + + /** + * Returns the names of the sub nodes of this preference node. + * This method only has to return any not yet cached child names, + * but may return all names if that is easier. It must not return + * null when there are no children, it has to return an empty array + * in that case. Since this method must consult the backing store to + * get all the sub node names it may throw a BackingStoreException. + * <p> + * Called by <code>childrenNames()</code> with this node locked. + */ + protected abstract String[] childrenNamesSpi() throws BackingStoreException; + + /** + * Returns a child note with the given name. + * This method is called by the <code>node()</code> method (indirectly + * through the <code>getNode()</code> helper method) with this node locked + * if a sub node with this name does not already exist in the child cache. + * If the child node did not aleady exist in the backing store the boolean + * field <code>newNode</code> of the returned node should be set. + * <p> + * Note that this method should even return a non-null child node if the + * backing store is not available since it may not throw a + * <code>BackingStoreException</code>. + */ + protected abstract AbstractPreferences childSpi(String name); + + /** + * Returns an (possibly empty) array with all the keys of the preference + * entries of this node. + * <p> + * Called by <code>keys()</code> with this node locked if this node has + * not been removed. May throw an exception when the backing store cannot + * be accessed. + * + * @exception BackingStoreException when the backing store cannot be + * reached + */ + protected abstract String[] keysSpi() throws BackingStoreException; + + /** + * Returns the value associated with the key in this preferences node or + * null when the key does not exist in this preferences node. + * <p> + * Called by <code>key()</code> with this node locked after checking that + * key is valid, not null and that the node has not been removed. + * <code>key()</code> will catch any exceptions that this method throws. + */ + protected abstract String getSpi(String key); + + /** + * Sets the value of the given preferences entry for this node. + * The implementation is not required to propagate the change to the + * backing store immediatly. It may not throw an exception when it tries + * to write to the backing store and that operation fails, the failure + * should be registered so a later invocation of <code>flush()</code> + * or <code>sync()</code> can signal the failure. + * <p> + * Called by <code>put()</code> with this node locked after checking that + * key and value are valid and non-null. + */ + protected abstract void putSpi(String key, String value); + + /** + * Removes the given key entry from this preferences node. + * The implementation is not required to propagate the change to the + * backing store immediatly. It may not throw an exception when it tries + * to write to the backing store and that operation fails, the failure + * should be registered so a later invocation of <code>flush()</code> + * or <code>sync()</code> can signal the failure. + * <p> + * Called by <code>remove()</code> with this node locked after checking + * that the key is valid and non-null. + */ + protected abstract void removeSpi(String key); + + /** + * Writes all entries of this preferences node that have not yet been + * written to the backing store and possibly creates this node in the + * backing store, if it does not yet exist. Should only write changes to + * this node and not write changes to any subnodes. + * Note that the node can be already removed in this VM. To check if + * that is the case the implementation can call <code>isRemoved()</code>. + * <p> + * Called (indirectly) by <code>flush()</code> with this node locked. + */ + protected abstract void flushSpi() throws BackingStoreException; + + /** + * Writes all entries of this preferences node that have not yet been + * written to the backing store and reads any entries that have changed + * in the backing store but that are not yet visible in this VM. + * Should only sync this node and not change any of the subnodes. + * Note that the node can be already removed in this VM. To check if + * that is the case the implementation can call <code>isRemoved()</code>. + * <p> + * Called (indirectly) by <code>sync()</code> with this node locked. + */ + protected abstract void syncSpi() throws BackingStoreException; + + /** + * Clears this node from this VM and removes it from the backing store. + * After this method has been called the node is marked as removed. + * <p> + * Called (indirectly) by <code>removeNode()</code> with this node locked + * after all the sub nodes of this node have already been removed. + */ + protected abstract void removeNodeSpi() throws BackingStoreException; +} |
