src/java/org/apache/commons/jelly/tags/core/FileTag.java

/*
 * Copyright 2002,2004 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.
 */
package org.apache.commons.jelly.tags.core;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;

import org.apache.commons.jelly.JellyTagException;
import org.apache.commons.jelly.TagSupport;
import org.apache.commons.jelly.XMLOutput;
import org.apache.commons.jelly.util.SafeContentHandler;
import org.dom4j.io.HTMLWriter;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.xml.sax.SAXException;

/**
 * A tag that pipes its body to a file denoted by the name attribute or to an in memory String
 * which is then output to a variable denoted by the var variable.
 *
 * @author <a href="mailto:vinayc@apache.org">Vinay Chandran</a>
 */
public class FileTag extends TagSupport {
    private boolean doAppend = false;
    private String var;
    private String name;
    private boolean omitXmlDeclaration = false;
    private String outputMode = "xml";
    private boolean prettyPrint;
    private String encoding;

    public FileTag(){
    }

    // Tag interface
    //-------------------------------------------------------------------------
    public void doTag(final XMLOutput output) throws JellyTagException {
        try {
            if ( name != null ) {
                String encoding = (this.encoding != null) ? this.encoding : "UTF-8";
                Writer writer = new OutputStreamWriter( new FileOutputStream( name, doAppend ), encoding );
                writeBody(writer);
            }
            else if (var != null) {
                StringWriter writer = new StringWriter();
                writeBody(writer);
                context.setVariable(var, writer.toString());
            }
            else {
                throw new JellyTagException( "This tag must have either the 'name' or the 'var' variables defined" );
            }
        } catch (FileNotFoundException e) {
            throw new JellyTagException(e);
        } catch (UnsupportedEncodingException e) {
            throw new JellyTagException(e);
        } catch (SAXException e) {
            throw new JellyTagException("could not write file",e);
        }
    }

    // Properties
    //-------------------------------------------------------------------------

    /**
     * Sets the file name for the output
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * Sets whether the XML declaration should be output or not
     */
    public void setOmitXmlDeclaration(boolean omitXmlDeclaration) {
        this.omitXmlDeclaration = omitXmlDeclaration;
    }


    /**
     * Sets the output mode, whether XML or HTML
     */
    public void setOutputMode(String outputMode) {
        this.outputMode = outputMode;
    }

    /**
     * Sets whether pretty printing mode is turned on. The default is off so that whitespace is preserved
     */
    public void setPrettyPrint(boolean prettyPrint) {
        this.prettyPrint = prettyPrint;
    }

    /**
     * Sets the XML encoding mode, which defaults to UTF-8
     */
    public void setEncoding(String encoding) {
        this.encoding = encoding;
    }
    
    /**
     * Sets wether to append at the end of the file
     * (not really something you normally do with an XML file).
     */
    public void setAppend(boolean doAppend) {
        this.doAppend = doAppend;
    }
    

    /**
     * Returns the var.
     * @return String
     */
    public String getVar() {
        return var;
    }

    /**
     * Sets the var.
     * @param var The var to set
     */
    public void setVar(String var) {
        this.var = var;
    }

    /**
     * Writes the body fo this tag to the given Writer
     */
    protected void writeBody(Writer writer) throws SAXException, JellyTagException {

        XMLOutput newOutput = createXMLOutput(writer);
        try {
            // we need to avoid multiple start/end document events
            newOutput.setContentHandler(
                new SafeContentHandler(newOutput.getContentHandler())
            );
            newOutput.startDocument();
            invokeBody(newOutput);
            newOutput.endDocument();
        }
        finally {
            try { newOutput.close(); } catch (IOException e) {}
        }
    }

    /**
     * A Factory method to create a new XMLOutput from the given Writer.
     */
    protected XMLOutput createXMLOutput(Writer writer) {

        OutputFormat format = null;
        if (prettyPrint) {
            format = OutputFormat.createPrettyPrint();
        }
        else {
            format = new OutputFormat();
        }
        if ( encoding != null ) {
            format.setEncoding( encoding );
        }
        if ( omitXmlDeclaration ) {
            format.setSuppressDeclaration(true);
        }

        boolean isHtml = outputMode != null && outputMode.equalsIgnoreCase( "html" );
        final XMLWriter xmlWriter = (isHtml)
            ? new HTMLWriter(writer, format)
            : new XMLWriter(writer, format);

        xmlWriter.setEscapeText(isEscapeText());

        XMLOutput answer = new XMLOutput() {
            public void close() throws IOException {
                xmlWriter.close();
            }
        };
        answer.setContentHandler(xmlWriter);
        answer.setLexicalHandler(xmlWriter);
        return answer;
    }
}