Annotation of java/classes/org/w3c/util/ObservableProperties.java, revision 1.9
1.1 abaird 1: // ObservableProperties.java
1.9 ! ylafon 2: // $Id: ObservableProperties.java,v 1.8 2000/08/16 21:37:58 ylafon Exp $
1.1 abaird 3: // (c) COPYRIGHT MIT and INRIA, 1996.
4: // Please first read the full copyright statement in file COPYRIGHT.html
5:
1.5 bmahe 6: package org.w3c.util;
1.1 abaird 7:
1.8 ylafon 8: import java.util.Hashtable;
9: import java.util.Properties;
10: import java.util.StringTokenizer;
11:
1.9 ! ylafon 12: import java.io.File;
1.1 abaird 13:
14: /**
15: * An enhanced property class that provides support to monitor changes.
16: * This class extends the basic properties class of Java, by providing
17: * monitoring support. It also provides more type conversion.
1.9 ! ylafon 18: *
1.1 abaird 19: * @see PropertyMonitoring
20: */
21:
22: public class ObservableProperties extends Properties {
1.3 abaird 23: private static final boolean debug = false;
24:
1.9 ! ylafon 25: PropertyMonitoring observers[] = null;
! 26: int observers_count = 0;
1.1 abaird 27:
28: /**
29: * Subscribe for property monitoring.
1.9 ! ylafon 30: *
! 31: * @param observer The object that handles the PropertyMonitoring
! 32: * interface.
! 33: */
! 34:
! 35: public synchronized void registerObserver(PropertyMonitoring o) {
! 36: // Try looking for an empty slot:
! 37: for (int i = 0; i < observers.length; i++) {
! 38: if (observers[i] == null) {
! 39: observers[i] = o;
! 40: return;
! 41: }
! 42: }
! 43: // Add the observer to the registered oned, resizing array if needed
! 44: if (observers_count + 1 >= observers.length) {
! 45: PropertyMonitoring m[] = new PropertyMonitoring[observers.length * 2];
! 46: System.arraycopy(observers, 0, m, 0, observers.length);
! 47: observers = m;
! 48: }
! 49: observers[observers_count++] = o;
1.1 abaird 50: }
51:
52: /**
53: * Unsubscribe this object from the observers list.
1.9 ! ylafon 54: *
1.1 abaird 55: * @param observer The observer to unsubscribe.
1.9 ! ylafon 56: * @return A boolean <strong>true</strong> if object was succesfully
! 57: * unsubscribed, <strong>false</strong> otherwise.
1.1 abaird 58: */
59:
1.9 ! ylafon 60: public synchronized boolean unregisterObserver(PropertyMonitoring o) {
! 61: for (int i = 0; i < observers.length; i++) {
! 62: if (observers[i] == o) {
! 63: observers[i] = null;
! 64: return true;
! 65: }
! 66: }
! 67: return false;
1.1 abaird 68: }
1.9 ! ylafon 69:
1.1 abaird 70: /**
71: * Update a property value.
72: * Assign a value to a property. If the property value has really changed
73: * notify our observers of the change.
1.9 ! ylafon 74: *
! 75: * @param name The name of the property to assign.
1.1 abaird 76: * @param value The new value for this property, or <strong>null</strong>
1.9 ! ylafon 77: * if the property setting is to be cancelled.
! 78: * @return A boolean <strong>true</strong> if change was accepted by
! 79: * our observers, <strong>false</strong> otherwise.
! 80: */
! 81:
! 82: public synchronized boolean putValue(String name, String value) {
! 83: if (debug) {
! 84: System.out.println("ObservableProperties: put " + name + "=[" + value
! 85: + "]");
! 86: }
! 87: // If null value, remove the prop definition:
! 88: if (value == null) {
! 89: super.remove(name);
! 90: return true;
! 91: }
! 92: // Otherwise, proceed:
! 93: String old = (String) get(name);
! 94: if ((old == null) || (!old.equals(value))) {
! 95: super.put(name, value);
! 96: for (PropertyMonitoring observer : observers) {
! 97: if (debug) {
! 98: if (observer != null) {
! 99: System.out.println("ObservableProperties: notifies "
! 100: + observer);
! 101: }
! 102: }
! 103: if (observer != null && !observer.propertyChanged(name)) {
! 104: if (old != null) {
! 105: super.put(name, old);
! 106: }
! 107: return false;
! 108: }
! 109: }
! 110: }
! 111: return true;
1.1 abaird 112: }
1.8 ylafon 113:
1.1 abaird 114: /**
115: * Get this property value, as a boolean.
1.9 ! ylafon 116: *
1.1 abaird 117: * @param name The name of the property to be fetched.
1.9 ! ylafon 118: * @param def The default value, if the property isn't defined.
1.1 abaird 119: * @return A Boolean instance.
120: */
121:
122: public boolean getBoolean(String name, boolean def) {
1.9 ! ylafon 123: String v = getProperty(name, null);
! 124: if (v != null) {
! 125: return Boolean.parseBoolean(v);
! 126: }
! 127: return def;
1.1 abaird 128: }
129:
130: /**
131: * Get this property value, as a String.
1.9 ! ylafon 132: *
1.1 abaird 133: * @param name The name of the property to be fetched.
1.9 ! ylafon 134: * @param def The default value, if the property isn't defined.
1.1 abaird 135: * @return An instance of String.
136: */
137:
138: public String getString(String name, String def) {
1.9 ! ylafon 139: String v = getProperty(name, null);
! 140: return (v == null) ? def : v;
1.1 abaird 141: }
142:
143: /**
144: * Get this property as a String array.
145: * By convention, properties that are get as string arrays should be
146: * encoded as a <strong>|</strong> separated list of Strings.
1.9 ! ylafon 147: *
1.1 abaird 148: * @param name The property's name.
1.9 ! ylafon 149: * @param def The default value (if undefined).
1.1 abaird 150: * @return A String array, or <strong>null</strong> if the property
1.9 ! ylafon 151: * is undefined.
1.1 abaird 152: */
153:
154: public String[] getStringArray(String name, String def[]) {
1.9 ! ylafon 155: String v = getProperty(name, null);
! 156: if (v == null) {
! 157: return def;
! 158: }
! 159: // Parse the property value:
! 160: StringTokenizer st = new StringTokenizer(v, "|");
! 161: int len = st.countTokens();
! 162: String ret[] = new String[len];
! 163: for (int i = 0; i < ret.length; i++) {
! 164: ret[i] = st.nextToken();
! 165: }
! 166: return ret;
1.1 abaird 167: }
168:
169: /**
170: * Get this property value, as an integer.
1.9 ! ylafon 171: *
1.1 abaird 172: * @param name The name of the property to be fetched.
1.9 ! ylafon 173: * @param def The default value, if the property isn't defined.
1.2 abaird 174: * @return An integer value.
1.1 abaird 175: */
176:
177: public int getInteger(String name, int def) {
1.9 ! ylafon 178: String v = getProperty(name, null);
! 179: if (v != null) {
! 180: try {
! 181: if (v.startsWith("0x")) {
! 182: return Integer.valueOf(v.substring(2), 16).intValue();
! 183: }
! 184: if (v.startsWith("#")) {
! 185: return Integer.valueOf(v.substring(1), 16).intValue();
! 186: }
! 187: return Integer.valueOf(v).intValue();
! 188: } catch (NumberFormatException e) {
! 189: }
! 190: }
! 191: return def;
1.6 bmahe 192: }
193:
194: public long getLong(String name, long def) {
1.9 ! ylafon 195: String v = getProperty(name, null);
! 196: if (v != null) {
! 197: try {
! 198: return Long.valueOf(v).longValue();
! 199: } catch (NumberFormatException e) {
! 200: }
! 201: }
! 202: return def;
1.2 abaird 203: }
204:
205: /**
206: * Get this property value, as a double.
1.9 ! ylafon 207: *
1.2 abaird 208: * @param name The name of the property.
1.9 ! ylafon 209: * @param def The default value if undefined.
1.2 abaird 210: * @return A double value.
211: */
212:
213: public double getDouble(String name, double def) {
1.9 ! ylafon 214: String v = getProperty(name, null);
! 215: if (v != null) {
! 216: try {
! 217: return Double.valueOf(v).doubleValue();
! 218: } catch (NumberFormatException ex) {
! 219: }
! 220: }
! 221: return def;
1.1 abaird 222: }
223:
224: /**
225: * Get this property value, as a File.
1.9 ! ylafon 226: *
1.1 abaird 227: * @param name The name of the property to be fetched.
1.9 ! ylafon 228: * @param def The default value, if the property isn't defined.
1.1 abaird 229: * @return An instance of File.
230: */
231:
232: public File getFile(String name, File def) {
1.9 ! ylafon 233: String v = getProperty(name, null);
! 234: if (v != null)
! 235: return new File(v);
! 236: return def;
1.1 abaird 237: }
238:
239: /**
240: * Build an httpdProperties instance from a Properties instance.
1.9 ! ylafon 241: *
1.1 abaird 242: * @param props The Properties instance.
243: */
244:
245: public ObservableProperties(Properties props) {
1.9 ! ylafon 246: super(props);
! 247: this.observers = new PropertyMonitoring[5];
! 248: this.observers_count = 0;
1.1 abaird 249: }
1.8 ylafon 250:
1.1 abaird 251: }
252:
253:
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