Source for gnu.java.util.prefs.NodeWriter

   1: /* NodeWriter - Writes and exports preferences nodes to files
   2:    Copyright (C) 2001 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10:  
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package gnu.java.util.prefs;
  39: 
  40: import java.io.BufferedWriter;
  41: import java.io.IOException;
  42: import java.io.OutputStream;
  43: import java.io.OutputStreamWriter;
  44: import java.io.Writer;
  45: 
  46: import java.util.StringTokenizer;
  47: 
  48: import java.util.prefs.*;
  49: 
  50: /**
  51:  * Writes and exports preferences nodes to files
  52:  *
  53:  * @author Mark Wielaard (mark@klomp.org)
  54:  */
  55: public class NodeWriter {
  56: 
  57:     /** The Preferences node to write. */
  58:     private final Preferences prefs;
  59: 
  60:     /** The bufferedWriter to write the node to. */
  61:     private final BufferedWriter bw;
  62: 
  63:     /**
  64:      * True if the complete sub tree should be written,
  65:      * false if only the node should be written.
  66:      */
  67:     private boolean subtree;
  68: 
  69:     /**
  70:      * Creates a new NodeWriter for the given preferences node and writer.
  71:      */
  72:     public NodeWriter(Preferences prefs, Writer w) {
  73:         this.prefs = prefs;
  74:         if (w instanceof BufferedWriter) {
  75:             this.bw = (BufferedWriter) w;
  76:         } else {
  77:             this.bw = new BufferedWriter(w);
  78:         }
  79:     }
  80: 
  81:     /**
  82:      * Creates a new NodeWriter for the given preferences node and
  83:      * outputstream. Creates a new OutputStreamWriter.
  84:      */
  85:     public NodeWriter(Preferences prefs, OutputStream os) {
  86:         this(prefs, new OutputStreamWriter(os));
  87:     }
  88: 
  89:     /**
  90:      * Writes the preference node plus the complete subtree.
  91:      */
  92:     public void writePrefsTree() throws BackingStoreException, IOException {
  93:         subtree = true;
  94:         writeHeader();
  95:         writePreferences();
  96:         bw.flush();
  97:     }
  98: 
  99:     /**
 100:      * Writes only the preference node.
 101:      */
 102:     public void writePrefs() throws BackingStoreException, IOException {
 103:         subtree = false;
 104:         writeHeader();
 105:         writePreferences();
 106:         bw.flush();
 107:     }
 108: 
 109:     /**
 110:      * Writes the standard header.
 111:      */
 112:     private void writeHeader() throws BackingStoreException, IOException {
 113:         bw.write("<?xml version=\"1.0\"?>");
 114:         bw.newLine();
 115:         bw.newLine();
 116:         bw.write("<!-- GNU Classpath java.util.prefs Preferences ");
 117: 
 118:         if (prefs.isUserNode()) {
 119:             bw.write("user");
 120:         } else {
 121:             bw.write("system");
 122:         }
 123: 
 124:         // root node?
 125:         if (prefs.parent() == null) {
 126:             bw.write(" root");
 127:         }
 128: 
 129:         if (subtree) {
 130:             bw.write(" tree");
 131:         } else {
 132:             bw.write(" node");
 133:         }
 134: 
 135:         // no root?
 136:         if (prefs.parent() != null) {
 137:             bw.newLine();
 138:             bw.write("     '");
 139:             bw.write(prefs.absolutePath());
 140:             bw.write('\'');
 141:             bw.newLine();
 142:         }
 143:         bw.write(" -->");
 144:         bw.newLine();
 145:         bw.newLine();
 146:     }
 147: 
 148:     /**
 149:      * Write the preferences tag and the root.
 150:      */
 151:     private void writePreferences() throws BackingStoreException, IOException {
 152:         bw.write("<preferences>");
 153:         bw.newLine();
 154:         writeRoot();
 155:         bw.write("</preferences>");
 156:         bw.newLine();
 157:     }
 158: 
 159:     private void writeRoot() throws BackingStoreException, IOException {
 160:         bw.write("  <root type=\"");
 161:         if (prefs.isUserNode()) {
 162:             bw.write("user");
 163:         } else {
 164:             bw.write("system");
 165:         }
 166:         bw.write("\"/>");
 167: 
 168:         writeRootMap();
 169:         writeNode();
 170: 
 171:         bw.write("  </root>");
 172:         bw.newLine();
 173:     }
 174: 
 175:     private void writeRootMap() throws BackingStoreException, IOException {
 176:         // Is it a root node?
 177:         if(prefs.parent() == null && prefs.keys().length > 0) {
 178:             bw.newLine();
 179:             writeMap(prefs, 2);
 180:         } else {
 181:             bw.write("<map/>");
 182:             bw.newLine();
 183:         }
 184:     }
 185: 
 186:     /**
 187:      * Writes all the parents of the preferences node without any entries.
 188:      * Returns the number of parents written, which has to be used as
 189:      * argument to <code>writeCloseParents()</code> after writing the node
 190:      * itself.
 191:      */
 192:     private int writeParents() throws IOException {
 193:         int parents;
 194:         String path = prefs.absolutePath();
 195:         int lastslash = path.lastIndexOf("/");
 196:         if (lastslash > 0) {
 197:             path = path.substring(1, lastslash);
 198:             StringTokenizer st = new StringTokenizer(path);
 199:             parents = st.countTokens();
 200: 
 201:             System.out.println("path: " + path);
 202:             System.out.println("parents: " + parents);
 203: 
 204:             for (int i=0; i<parents; i++) {
 205:                 String name = st.nextToken();
 206:                 indent(i+2);
 207:                 bw.write("<node name=\"" + name + "\">");
 208:                 bw.write("<map/>");
 209:                 bw.write("</node>");
 210:                 bw.newLine();
 211:             }
 212:         } else {
 213:             parents = 0;
 214:         }
 215: 
 216:         return parents;
 217:     }
 218: 
 219:     private void writeCloseParents(int parents) throws IOException {
 220:         while(parents > 0) {
 221:             indent(parents+1);
 222:             bw.write("</node>");
 223:             bw.newLine();
 224:             parents--;
 225:         }
 226:     }
 227: 
 228:     private void writeNode() throws BackingStoreException, IOException {
 229:         int parents = writeParents();
 230:         // root?
 231:         int indent;
 232:         if (prefs.parent() == null) {
 233:             indent = parents+1;
 234:         } else {
 235:             indent = parents+2;
 236:         }
 237:         writeNode(prefs, indent);
 238:         writeCloseParents(parents);
 239:     }
 240: 
 241:     private void writeNode(Preferences node, int indent)
 242:                                     throws BackingStoreException, IOException
 243:     {
 244:         // not root?
 245:         if (node.parent() != null) {
 246:             indent(indent);
 247:             bw.write("<node name=\"" + node.name() + "\">");
 248:             if (node.keys().length > 0) {
 249:                 bw.newLine();
 250:             }
 251:             writeMap(node, indent+1);
 252:         }
 253: 
 254:         if (subtree) {
 255:             String[] children = node.childrenNames();
 256:             for (int i=0; i<children.length; i++) {
 257:                 Preferences child = node.node(children[i]);
 258:                 writeNode(child, indent+1);
 259:             }
 260:         }
 261: 
 262:         // not root?
 263:         if (node.parent() != null) {
 264:             indent(indent);
 265:             bw.write("</node>");
 266:             bw.newLine();
 267:         }
 268:     }
 269: 
 270:     private void writeMap(Preferences node, int indent) 
 271:                                     throws BackingStoreException, IOException
 272:     {
 273:         // construct String used for indentation
 274:         StringBuffer indentBuffer = new StringBuffer(2*indent);
 275:         for (int i=0; i < indent; i++)
 276:             indentBuffer.append("  ");
 277:         String indentString = indentBuffer.toString();
 278: 
 279:         if (node.keys().length > 0) {
 280:             bw.write(indentString);
 281:             bw.write("<map>");
 282:             bw.newLine();
 283:             writeEntries(node, indentString + "  ");
 284:             bw.write(indentString);
 285:             bw.write("</map>");
 286:         } else {
 287:             bw.write("<map/>");
 288:         }
 289:         bw.newLine();
 290:     }
 291: 
 292:     private void writeEntries(Preferences node, String indent)
 293:                                     throws BackingStoreException, IOException
 294:     {
 295:         String[] keys = node.keys();
 296:         for(int i = 0; i < keys.length; i++) {
 297:             String value = node.get(keys[i], null);
 298:             if (value == null) {
 299:                 throw new BackingStoreException("null value for key '"
 300:                                                 + keys[i] + "'");
 301:             }
 302: 
 303:             bw.write(indent);
 304:             bw.write("<entry key=\"" + keys[i] + "\""
 305:                     + " value=\"" + value + "\"/>");
 306:             bw.newLine();
 307:         }
 308:     }
 309: 
 310:     private void indent(int x) throws IOException {
 311:         for (int i=0; i<x; i++) {
 312:             bw.write("  ");
 313:         }
 314:     }
 315: }