org.directwebremoting.dwrp.PlainScriptConduit Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.dwrp;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.directwebremoting.extend.EnginePrivate;
import org.directwebremoting.extend.ProtocolConstants;
import org.directwebremoting.util.MimeConstants;

/**
 * A ScriptConduit for use with plain Javascript output.
 * Scripts are plain Javascript without 'execute-in-parent-context' wrapping,
 * but with script-start and script-end markers.
 * 
If this conduit is used the client should direct the output to an iframe
 * and then poll, looking for new data into the iframe. The html tags should be
 * removed and script between script-start and script-end tags eval()ed.
 * This conduit is useful for Firefox. It will not work as it stands with IE
 * 6/7 because they don't allow the browser to see data entering an iframe until
 * it overflows a 4k buffer.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class PlainScriptConduit extends BaseScriptConduit
{
    /**
     * Simple ctor
     */
    public PlainScriptConduit(PrintWriter out, String instanceId, String scriptTagProtection)
    {
        super(out, instanceId);
        this.scriptTagProtection = scriptTagProtection;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#getOutboundMimeType()
     */
    public String getOutboundMimeType()
    {
        return MimeConstants.MIME_JS;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#beginStreamAndChunk()
     */
    public void beginStreamAndChunk()
    {
        if (scriptTagProtection != null)
        {
            out.println(scriptTagProtection);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#beginChunk()
     */
    public void beginChunk()
    {
        if (!chunkOpen) {
            out.println(ProtocolConstants.SCRIPT_START_MARKER);
            out.println(EnginePrivate.remoteBeginWrapper(instanceId, false, null));
            chunkOpen = true;
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#sendScript(java.lang.String)
     */
    public void sendScript(String script)
    {
        if (log.isDebugEnabled()) {
            log.debug("Execution time: " + new Date().toString() + " - Writing to response: " + script);
        }
        beginChunk();
        out.println(script);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#endChunk()
     */
    public void endChunk()
    {
        if (chunkOpen) {
            out.println(EnginePrivate.remoteEndWrapper(instanceId, false));
            out.println(ProtocolConstants.SCRIPT_END_MARKER);
            chunkOpen = false;
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.ScriptConduit#endStream(java.io.PrintWriter, int)
     */
    public void endStreamAndChunk() throws IOException
    {
        endChunk();
    }

    private final String scriptTagProtection;

    /**
     * Is a chunk section currently open on the output?
     */
    private boolean chunkOpen = false;

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(PlainScriptConduit.class);
}