diff options
Diffstat (limited to 'libjava/classpath/java/beans/XMLEncoder.java')
-rw-r--r-- | libjava/classpath/java/beans/XMLEncoder.java | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/libjava/classpath/java/beans/XMLEncoder.java b/libjava/classpath/java/beans/XMLEncoder.java new file mode 100644 index 000000000..40cb6dbfb --- /dev/null +++ b/libjava/classpath/java/beans/XMLEncoder.java @@ -0,0 +1,267 @@ +/* XMLEncoder.java + Copyright (C) 2004, 2005 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.beans; + +import gnu.java.beans.encoder.ScanEngine; + +import java.io.OutputStream; + +/** + * This class uses the {@link PersistenceDelegate} and {@link Encoder} + * infrastructure to generate an XML representation of the objects it + * serializes. + * + * @author Robert Schuster (robertschuster@fsfe.org) + * @since 1.4 + */ +public class XMLEncoder extends Encoder +{ + Object owner; + + Exception exception; + + ScanEngine scanEngine; + + private int accessCounter = 0; + + public XMLEncoder(OutputStream os) + { + scanEngine = new ScanEngine(os); + } + + public void close() + { + if (scanEngine != null) + { + scanEngine.close(); + scanEngine = null; + } + } + + public void flush() + { + scanEngine.flush(); + } + + public void writeExpression(Expression expr) + { + // Implementation note: Why is this method overwritten and nearly exactly + // reimplemented as in Encoder? + // The Encoder class can (and should be) subclassed by users outside of the + // java.beans package. While I have doubts that this is possible from an + // API design point of view I tried to replicate the Encoder's behavior + // in the JDK as exactly as possible. This strictness however made it + // extremely complicated to implement the XMLEncoder's backend. Therefore + // I decided to copy the Encoder's implementation and make all changes + // I needed for a succesfull operation of XMLEncoder. + // + // The same is true for the writeStatement method. + + // Silently ignore out of bounds calls. + if (accessCounter <= 0) + return; + + scanEngine.writeExpression(expr); + + + Object target = expr.getTarget(); + Object value = null; + Object newValue = null; + + try + { + value = expr.getValue(); + } + catch (Exception e) + { + getExceptionListener().exceptionThrown(e); + return; + } + + + newValue = get(value); + + if (newValue == null) + { + Object newTarget = get(target); + if (newTarget == null) + { + writeObject(target); + newTarget = get(target); + + // May happen if exception was thrown. + if (newTarget == null) + { + return; + } + } + + Object[] args = expr.getArguments(); + Object[] newArgs = new Object[args.length]; + + for (int i = 0; i < args.length; i++) + { + newArgs[i] = get(args[i]); + if (newArgs[i] == null || isImmutableType(args[i].getClass())) + { + writeObject(args[i]); + newArgs[i] = get(args[i]); + } + } + + Expression newExpr = new Expression(newTarget, expr.getMethodName(), + newArgs); + + // Fakes the result of Class.forName(<primitiveType>) to make it possible + // to hand such a type to the encoding process. + if (value instanceof Class && ((Class) value).isPrimitive()) + newExpr.setValue(value); + + // Instantiates the new object. + try + { + newValue = newExpr.getValue(); + + putCandidate(value, newValue); + } + catch (Exception e) + { + getExceptionListener().exceptionThrown(e); + + // In Statement.writeExpression we had no possibility to flags + // an erroneous state to the ScanEngine without behaving different + // to the JDK. + scanEngine.revoke(); + + return; + } + + writeObject(value); + + } + else if(value.getClass() == String.class || value.getClass() == Class.class) + { + writeObject(value); + } + + scanEngine.end(); + } + + public void writeStatement(Statement stmt) + { + // In case of questions have a at the implementation note in + // writeExpression. + + scanEngine.writeStatement(stmt); + + // Silently ignore out of bounds calls. + if (accessCounter <= 0) + return; + + Object target = stmt.getTarget(); + + Object newTarget = get(target); + if (newTarget == null) + { + writeObject(target); + newTarget = get(target); + } + + Object[] args = stmt.getArguments(); + Object[] newArgs = new Object[args.length]; + + for (int i = 0; i < args.length; i++) + { + // Here is the difference to the original writeStatement + // method in Encoder. In case that the object is known or + // not an immutable we put it directly into the ScanEngine + // which will then generate an object reference for it. + newArgs[i] = get(args[i]); + if (newArgs[i] == null || isImmutableType(args[i].getClass())) + { + writeObject(args[i]); + newArgs[i] = get(args[i]); + } + else + scanEngine.writeObject(args[i]); + } + + Statement newStmt = new Statement(newTarget, stmt.getMethodName(), newArgs); + + try + { + newStmt.execute(); + } + catch (Exception e) + { + getExceptionListener().exceptionThrown(e); + + // In Statement.writeStatement we had no possibility to flags + // an erroneous state to the ScanEngine without behaving different + // to the JDK. + scanEngine.revoke(); + return; + } + + scanEngine.end(); + } + + public void writeObject(Object o) + { + accessCounter++; + + scanEngine.writeObject(o); + + if (get(o) == null) + super.writeObject(o); + + accessCounter--; + } + + public void setOwner(Object o) + { + owner = o; + } + + public Object getOwner() + { + return owner; + } + +} |