Struts example source code file (CallbackWriter.java)

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

Java - Struts tags/keywords

callbackwriter, component, end_evaluation, evaluate_body, io, ioexception, ioexception, repeat_evaluation, skip_body, stringwriter, stringwriter, templatemodelexception, templatemodelexception, writer, writer

The Struts CallbackWriter.java source code

/*
 * $Id: CallbackWriter.java 651946 2008-04-27 13:41:38Z apetrelli $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

package org.apache.struts2.views.freemarker.tags;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;

import org.apache.struts2.components.Component;

import freemarker.template.TemplateModelException;
import freemarker.template.TransformControl;

/**
 */
public class CallbackWriter extends Writer implements TransformControl {
    private Component bean;
    private Writer writer;
    private StringWriter body;
    private boolean afterBody = false;

    public CallbackWriter(Component bean, Writer writer) {
        this.bean = bean;
        this.writer = writer;

        if (bean.usesBody()) {
            this.body = new StringWriter();
        }
    }

    public void close() throws IOException {
        if (bean.usesBody()) {
            body.close();
        }
    }

    public void flush() throws IOException {
        writer.flush();

        if (bean.usesBody()) {
            body.flush();
        }
    }

    public void write(char cbuf[], int off, int len) throws IOException {
        if (bean.usesBody() && !afterBody) {
            body.write(cbuf, off, len);
        } else {
            writer.write(cbuf, off, len);
        }
    }

    public int onStart() throws TemplateModelException, IOException {
        boolean result = bean.start(this);

        if (result) {
            return EVALUATE_BODY;
        } else {
            return SKIP_BODY;
        }
    }

    public int afterBody() throws TemplateModelException, IOException {
        afterBody = true;
        boolean result = bean.end(this, bean.usesBody() ? body.toString() : "");

        if (result) {
            return REPEAT_EVALUATION;
        } else {
            return END_EVALUATION;
        }
    }

    public void onError(Throwable throwable) throws Throwable {
        throw throwable;
    }

    public Component getBean() {
        return bean;
    }
}