Source for gnu.java.util.prefs.NodeWriter

   1: /* NodeWriter - Writes and exports preferences nodes to files
   2:    Copyright (C) 2001, 2006 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 gnu.java.lang.CPStringBuilder;
  41: 
  42: import java.io.BufferedWriter;
  43: import java.io.IOException;
  44: import java.io.OutputStream;
  45: import java.io.OutputStreamWriter;
  46: import java.io.UnsupportedEncodingException;
  47: import java.io.Writer;
  48: 
  49: import java.util.StringTokenizer;
  50: 
  51: import java.util.prefs.*;
  52: 
  53: /**
  54:  * Writes and exports preferences nodes to files
  55:  *
  56:  * @author Mark Wielaard (mark@klomp.org)
  57:  */
  58: public class NodeWriter {
  59: 
  60:     /** The Preferences node to write. */
  61:     private final Preferences prefs;
  62: 
  63:     /** The bufferedWriter to write the node to. */
  64:     private final BufferedWriter bw;
  65: 
  66:     /**
  67:      * True if the complete sub tree should be written,
  68:      * false if only the node should be written.
  69:      */
  70:     private boolean subtree;
  71: 
  72:     /**
  73:      * Creates a new NodeWriter for the given preferences node and
  74:      * outputstream. Creates a new OutputStreamWriter.
  75:      */
  76:     public NodeWriter(Preferences prefs, OutputStream os) {
  77:         this.prefs = prefs;
  78:         Writer w;
  79:         try
  80:           {
  81:             w = new OutputStreamWriter(os, "UTF-8");
  82:           }
  83:         catch (UnsupportedEncodingException uee)
  84:           {
  85:             // Shouldn't happen, since we always have UTF-8 available.
  86:             InternalError ie = new InternalError("UTF-8 encoding missing");
  87:             ie.initCause(uee);
  88:             throw ie;
  89:           }
  90:         this.bw = new BufferedWriter(w);
  91:     }
  92: 
  93:     /**
  94:      * Writes the preference node plus the complete subtree.
  95:      */
  96:     public void writePrefsTree() throws BackingStoreException, IOException {
  97:         subtree = true;
  98:         writeHeader();
  99:         writePreferences();
 100:         bw.flush();
 101:     }
 102: 
 103:     /**
 104:      * Writes only the preference node.
 105:      */
 106:     public void writePrefs() throws BackingStoreException, IOException {
 107:         subtree = false;
 108:         writeHeader();
 109:         writePreferences();
 110:         bw.flush();
 111:     }
 112: 
 113:     /**
 114:      * Writes the standard header.
 115:      */
 116:     private void writeHeader() throws BackingStoreException, IOException {
 117:         bw.write("<?xml version=\"1.0\"?>");
 118:         bw.newLine();
 119:         bw.write("<!DOCTYPE preferences SYSTEM "
 120:                  + "\"http://java.sun.com/dtd/preferences.dtd\">");
 121:         bw.newLine();
 122:         bw.newLine();
 123:         bw.write("<!-- GNU Classpath java.util.prefs Preferences ");
 124: 
 125:         if (prefs.isUserNode()) {
 126:             bw.write("user");
 127:         } else {
 128:             bw.write("system");
 129:         }
 130: 
 131:         // root node?
 132:         if (prefs.parent() == null) {
 133:             bw.write(" root");
 134:         }
 135: 
 136:         if (subtree) {
 137:             bw.write(" tree");
 138:         } else {
 139:             bw.write(" node");
 140:         }
 141: 
 142:         // no root?
 143:         if (prefs.parent() != null) {
 144:             bw.newLine();
 145:             bw.write("     '");
 146:             bw.write(prefs.absolutePath());
 147:             bw.write('\'');
 148:             bw.newLine();
 149:         }
 150:         bw.write(" -->");
 151:         bw.newLine();
 152:         bw.newLine();
 153:     }
 154: 
 155:     /**
 156:      * Write the preferences tag and the root.
 157:      */
 158:     private void writePreferences() throws BackingStoreException, IOException {
 159:         bw.write("<preferences>");
 160:         bw.newLine();
 161:         writeRoot();
 162:         bw.write("</preferences>");
 163:         bw.newLine();
 164:     }
 165: 
 166:     private void writeRoot() throws BackingStoreException, IOException {
 167:         bw.write("  <root type=\"");
 168:         if (prefs.isUserNode()) {
 169:             bw.write("user");
 170:         } else {
 171:             bw.write("system");
 172:         }
 173:         bw.write("\">");
 174: 
 175:         writeRootMap();
 176:         writeNode();
 177: 
 178:         bw.write("  </root>");
 179:         bw.newLine();
 180:     }
 181: 
 182:     private void writeRootMap() throws BackingStoreException, IOException {
 183:         // Is it a root node?
 184:         if(prefs.parent() == null && prefs.keys().length > 0) {
 185:             bw.newLine();
 186:             writeMap(prefs, 2);
 187:         } else {
 188:             bw.write("<map/>");
 189:             bw.newLine();
 190:         }
 191:     }
 192: 
 193:     /**
 194:      * Writes all the parents of the preferences node without any entries.
 195:      * Returns the number of parents written, which has to be used as
 196:      * argument to <code>writeCloseParents()</code> after writing the node
 197:      * itself.
 198:      */
 199:     private int writeParents() throws IOException {
 200:         int parents;
 201:         String path = prefs.absolutePath();
 202:         int lastslash = path.lastIndexOf("/");
 203:         if (lastslash > 0) {
 204:             path = path.substring(1, lastslash);
 205:             StringTokenizer st = new StringTokenizer(path);
 206:             parents = st.countTokens();
 207: 
 208:             for (int i=0; i<parents; i++) {
 209:                 String name = st.nextToken();
 210:                 indent(i+2);
 211:                 bw.write("<node name=\"" + name + "\">");
 212:                 bw.write("<map/>");
 213:                 bw.write("</node>");
 214:                 bw.newLine();
 215:             }
 216:         } else {
 217:             parents = 0;
 218:         }
 219: 
 220:         return parents;
 221:     }
 222: 
 223:     private void writeCloseParents(int parents) throws IOException {
 224:         while(parents > 0) {
 225:             indent(parents+1);
 226:             bw.write("</node>");
 227:             bw.newLine();
 228:             parents--;
 229:         }
 230:     }
 231: 
 232:     private void writeNode() throws BackingStoreException, IOException {
 233:         int parents = writeParents();
 234:         // root?
 235:         int indent;
 236:         if (prefs.parent() == null) {
 237:             indent = parents+1;
 238:         } else {
 239:             indent = parents+2;
 240:         }
 241:         writeNode(prefs, indent);
 242:         writeCloseParents(parents);
 243:     }
 244: 
 245:     private void writeNode(Preferences node, int indent)
 246:                                     throws BackingStoreException, IOException
 247:     {
 248:         // not root?
 249:         if (node.parent() != null) {
 250:             indent(indent);
 251:             bw.write("<node name=\"" + node.name() + "\">");
 252:             if (node.keys().length > 0) {
 253:                 bw.newLine();
 254:             }
 255:             writeMap(node, indent+1);
 256:         }
 257: 
 258:         if (subtree) {
 259:             String[] children = node.childrenNames();
 260:             for (int i=0; i<children.length; i++) {
 261:                 Preferences child = node.node(children[i]);
 262:                 writeNode(child, indent+1);
 263:             }
 264:         }
 265: 
 266:         // not root?
 267:         if (node.parent() != null) {
 268:             indent(indent);
 269:             bw.write("</node>");
 270:             bw.newLine();
 271:         }
 272:     }
 273: 
 274:     private void writeMap(Preferences node, int indent)
 275:                                     throws BackingStoreException, IOException
 276:     {
 277:         // construct String used for indentation
 278:         CPStringBuilder indentBuffer = new CPStringBuilder(2*indent);
 279:         for (int i=0; i < indent; i++)
 280:             indentBuffer.append("  ");
 281:         String indentString = indentBuffer.toString();
 282: 
 283:         if (node.keys().length > 0) {
 284:             bw.write(indentString);
 285:             bw.write("<map>");
 286:             bw.newLine();
 287:             writeEntries(node, indentString + "  ");
 288:             bw.write(indentString);
 289:             bw.write("</map>");
 290:         } else {
 291:             bw.write("<map/>");
 292:         }
 293:         bw.newLine();
 294:     }
 295: 
 296:     private void writeEntries(Preferences node, String indent)
 297:                                     throws BackingStoreException, IOException
 298:     {
 299:         String[] keys = node.keys();
 300:         for(int i = 0; i < keys.length; i++) {
 301:             String value = node.get(keys[i], null);
 302:             if (value == null) {
 303:                 throw new BackingStoreException("null value for key '"
 304:                                                 + keys[i] + "'");
 305:             }
 306: 
 307:             bw.write(indent);
 308:             bw.write("<entry key=\"" + keys[i] + "\""
 309:                     + " value=\"" + value + "\"/>");
 310:             bw.newLine();
 311:         }
 312:     }
 313: 
 314:     private void indent(int x) throws IOException {
 315:         for (int i=0; i<x; i++) {
 316:             bw.write("  ");
 317:         }
 318:     }
 319: }