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Java example source code file (Message.java)

This example Java source code file (Message.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

constantpoolgen, instruction, instructionlist, invokeinterface, invokespecial, push, string_sig, syntaxtreenode, text, typecheckerror, utf\-8, writer_sig

The Message.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: Message.java,v 1.2.4.1 2005/09/02 06:47:02 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.INVOKEINTERFACE;
import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.NEW;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class Message extends Instruction {
    private boolean _terminate = false;

    public void parseContents(Parser parser) {
        String termstr = getAttribute("terminate");
        if (termstr != null) {
            _terminate = termstr.equals("yes");
        }
        parseChildren(parser);
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
        typeCheckContents(stable);
        return Type.Void;
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();

        // Load the translet (for call to displayMessage() function)
        il.append(classGen.loadTranslet());

        switch (elementCount()) {
            case 0:
                il.append(new PUSH(cpg, ""));
            break;
            case 1:
                SyntaxTreeNode child = (SyntaxTreeNode) elementAt(0);
                if (child instanceof Text) {
                    il.append(new PUSH(cpg, ((Text) child).getText()));
                    break;
                }
                // falls through
            default:
                // Push current output handler onto the stack
                il.append(methodGen.loadHandler());

                // Replace the current output handler by a ToXMLStream
                il.append(new NEW(cpg.addClass(STREAM_XML_OUTPUT)));
                il.append(methodGen.storeHandler());

                // Push a reference to a StringWriter
                il.append(new NEW(cpg.addClass(STRING_WRITER)));
                il.append(DUP);
                il.append(DUP);
                il.append(new INVOKESPECIAL(
                    cpg.addMethodref(STRING_WRITER, "<init>", "()V")));

                // Load ToXMLStream
                il.append(methodGen.loadHandler());
                il.append(new INVOKESPECIAL(
                    cpg.addMethodref(STREAM_XML_OUTPUT, "<init>",
                                     "()V")));

                // Invoke output.setWriter(STRING_WRITER)
                il.append(methodGen.loadHandler());
                il.append(SWAP);
                il.append(new INVOKEINTERFACE(
                    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
                                              "setWriter",
                                              "("+WRITER_SIG+")V"), 2));

                // Invoke output.setEncoding("UTF-8")
                il.append(methodGen.loadHandler());
                il.append(new PUSH(cpg, "UTF-8"));   // other encodings?
                il.append(new INVOKEINTERFACE(
                    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
                                              "setEncoding",
                                              "("+STRING_SIG+")V"), 2));

                // Invoke output.setOmitXMLDeclaration(true)
                il.append(methodGen.loadHandler());
                il.append(ICONST_1);
                il.append(new INVOKEINTERFACE(
                    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
                                              "setOmitXMLDeclaration",
                                              "(Z)V"), 2));

                il.append(methodGen.loadHandler());
                il.append(new INVOKEINTERFACE(
                    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
                                              "startDocument",
                                              "()V"), 1));

                // Inline translation of contents
                translateContents(classGen, methodGen);

                il.append(methodGen.loadHandler());
                il.append(new INVOKEINTERFACE(
                    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
                                              "endDocument",
                                              "()V"), 1));

                // Call toString() on StringWriter
                il.append(new INVOKEVIRTUAL(
                    cpg.addMethodref(STRING_WRITER, "toString",
                                     "()" + STRING_SIG)));

                // Restore old output handler
                il.append(SWAP);
                il.append(methodGen.storeHandler());
            break;
        }

        // Send the resulting string to the message handling method
        il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
                                                     "displayMessage",
                                                     "("+STRING_SIG+")V")));

        // If 'terminate' attribute is set to 'yes': Instanciate a
        // RunTimeException, but it on the stack and throw an exception
        if (_terminate == true) {
            // Create a new instance of RunTimeException
            final int einit = cpg.addMethodref("java.lang.RuntimeException",
                                               "<init>",
                                               "(Ljava/lang/String;)V");
            il.append(new NEW(cpg.addClass("java.lang.RuntimeException")));
            il.append(DUP);
            il.append(new PUSH(cpg,"Termination forced by an " +
                                   "xsl:message instruction"));
            il.append(new INVOKESPECIAL(einit));
            il.append(ATHROW);
        }
    }

}

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