Struts example source code file (StreamResult.java)

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Java - Struts tags/keywords

actioninvocation, actioninvocation, can, http, httpservletresponse, inputstream, integer, io, logger, request, response, servlet, start, streaming, streaming, streamresult, streamresult, string, string

The Struts StreamResult.java source code

/*
 * $Id: StreamResult.java 817366 2009-09-21 18:40:56Z wesw $
 *
 * 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.dispatcher;

import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import com.opensymphony.xwork2.util.ValueStack;

/**
 * <!-- START SNIPPET: description -->
 *
 * A custom Result type for sending raw data (via an InputStream) directly to the
 * HttpServletResponse. Very useful for allowing users to download content.
 *
 * <!-- END SNIPPET: description -->
 * <p/>
 * <b>This result type takes the following parameters:
 *
 * <!-- START SNIPPET: params -->
 *
 * <ul>
 *
 * <li>contentType - the stream mime-type as sent to the web browser
 * (default = <code>text/plain).
 *
 * <li>contentLength - the stream length in bytes (the browser displays a
 * progress bar).</li>
 *
 * <li>contentDisposition - the content disposition header value for
 * specifing the file name (default = <code>inline, values are typically
 * <i>attachment;filename="document.pdf".
 *
 * <li>inputName - the name of the InputStream property from the chained
 * action (default = <code>inputStream).
 *
 * <li>bufferSize - the size of the buffer to copy from input to output
 * (default = <code>1024).
 *
 * <li>allowCaching if set to 'false' it will set the headers 'Pragma' and 'Cache-Control'
 * to 'no-cahce', and prevent client from caching the content. (default = <code>true)
 *
 * <li>contentCharSet if set to a string, ';charset=value' will be added to the
 * content-type header, where value is the string set. If set to an expression, the result
 * of evaluating the expression will be used. If not set, then no charset will be set on
 * the header</li>
 * </ul>
 * 
 * <p>These parameters can also be set by exposing a similarly named getter method on your Action.  For example, you can
 * provide <code>getContentType() to override that parameter for the current action.

 *
 * <!-- END SNIPPET: params -->
 *
 * <b>Example:
 *
 * <pre>
 * <result name="success" type="stream">
 *   <param name="contentType">image/jpeg</param>
 *   <param name="inputName">imageStream</param>
 *   <param name="contentDisposition">attachment;filename="document.pdf"</param>
 *   <param name="bufferSize">1024</param>
 * </result>
 * <!-- END SNIPPET: example -->

* */ public class StreamResult extends StrutsResultSupport { private static final long serialVersionUID = -1468409635999059850L; protected static final Logger LOG = LoggerFactory.getLogger(StreamResult.class); public static final String DEFAULT_PARAM = "inputName"; protected String contentType = "text/plain"; protected String contentLength; protected String contentDisposition = "inline"; protected String contentCharSet ; protected String inputName = "inputStream"; protected InputStream inputStream; protected int bufferSize = 1024; protected boolean allowCaching = true; public StreamResult() { super(); } public StreamResult(InputStream in) { this.inputStream = in; } /** * @return Returns the whether or not the client should be requested to allow caching of the data stream. */ public boolean getAllowCaching() { return allowCaching; } /** * Set allowCaching to <tt>false to indicate that the client should be requested not to cache the data stream. * This is set to <tt>false by default * * @param allowCaching Enable caching. */ public void setAllowCaching(boolean allowCaching) { this.allowCaching = allowCaching; } /** * @return Returns the bufferSize. */ public int getBufferSize() { return (bufferSize); } /** * @param bufferSize The bufferSize to set. */ public void setBufferSize(int bufferSize) { this.bufferSize = bufferSize; } /** * @return Returns the contentType. */ public String getContentType() { return (contentType); } /** * @param contentType The contentType to set. */ public void setContentType(String contentType) { this.contentType = contentType; } /** * @return Returns the contentLength. */ public String getContentLength() { return contentLength; } /** * @param contentLength The contentLength to set. */ public void setContentLength(String contentLength) { this.contentLength = contentLength; } /** * @return Returns the Content-disposition header value. */ public String getContentDisposition() { return contentDisposition; } /** * @param contentDisposition the Content-disposition header value to use. */ public void setContentDisposition(String contentDisposition) { this.contentDisposition = contentDisposition; } /** * @return Returns the charset specified by the user */ public String getContentCharSet() { return contentCharSet; } /** * @param contentCharSet the charset to use on the header when sending the stream */ public void setContentCharSet(String contentCharSet) { this.contentCharSet = contentCharSet; } /** * @return Returns the inputName. */ public String getInputName() { return (inputName); } /** * @param inputName The inputName to set. */ public void setInputName(String inputName) { this.inputName = inputName; } /** * @see org.apache.struts2.dispatcher.StrutsResultSupport#doExecute(java.lang.String, com.opensymphony.xwork2.ActionInvocation) */ protected void doExecute(String finalLocation, ActionInvocation invocation) throws Exception { // Override any parameters using values on the stack resolveParamsFromStack(invocation.getStack(), invocation); OutputStream oOutput = null; try { if (inputStream == null) { // Find the inputstream from the invocation variable stack inputStream = (InputStream) invocation.getStack().findValue(conditionalParse(inputName, invocation)); } if (inputStream == null) { String msg = ("Can not find a java.io.InputStream with the name [" + inputName + "] in the invocation stack. " + "Check the <param name=\"inputName\"> tag specified for this action."); LOG.error(msg); throw new IllegalArgumentException(msg); } // Find the Response in context HttpServletResponse oResponse = (HttpServletResponse) invocation.getInvocationContext().get(HTTP_RESPONSE); // Set the content type if (contentCharSet != null && ! contentCharSet.equals("")) { oResponse.setContentType(conditionalParse(contentType, invocation)+";charset="+contentCharSet); } else { oResponse.setContentType(conditionalParse(contentType, invocation)); } // Set the content length if (contentLength != null) { String _contentLength = conditionalParse(contentLength, invocation); int _contentLengthAsInt = -1; try { _contentLengthAsInt = Integer.parseInt(_contentLength); if (_contentLengthAsInt >= 0) { oResponse.setContentLength(_contentLengthAsInt); } } catch(NumberFormatException e) { LOG.warn("failed to recongnize "+_contentLength+" as a number, contentLength header will not be set", e); } } // Set the content-disposition if (contentDisposition != null) { oResponse.addHeader("Content-Disposition", conditionalParse(contentDisposition, invocation)); } // Set the cache control headers if neccessary if (!allowCaching) { oResponse.addHeader("Pragma", "no-cache"); oResponse.addHeader("Cache-Control", "no-cache"); } // Get the outputstream oOutput = oResponse.getOutputStream(); if (LOG.isDebugEnabled()) { LOG.debug("Streaming result [" + inputName + "] type=[" + contentType + "] length=[" + contentLength + "] content-disposition=[" + contentDisposition + "] charset=[" + contentCharSet + "]"); } // Copy input to output LOG.debug("Streaming to output buffer +++ START +++"); byte[] oBuff = new byte[bufferSize]; int iSize; while (-1 != (iSize = inputStream.read(oBuff))) { oOutput.write(oBuff, 0, iSize); } LOG.debug("Streaming to output buffer +++ END +++"); // Flush oOutput.flush(); } finally { if (inputStream != null) inputStream.close(); if (oOutput != null) oOutput.close(); } } /** * Tries to lookup the parameters on the stack. Will override any existing parameters * * @param stack The current value stack */ protected void resolveParamsFromStack(ValueStack stack, ActionInvocation invocation) { String disposition = stack.findString("contentDisposition"); if (disposition != null) { setContentDisposition(disposition); } String contentType = stack.findString("contentType"); if (contentType != null) { setContentType(contentType); } String inputName = stack.findString("inputName"); if (inputName != null) { setInputName(inputName); } String contentLength = stack.findString("contentLength"); if (contentLength != null) { setContentLength(contentLength); } Integer bufferSize = (Integer) stack.findValue("bufferSize", Integer.class); if (bufferSize != null) { setBufferSize(bufferSize.intValue()); } if (contentCharSet != null ) { contentCharSet = conditionalParse(contentCharSet, invocation); } else { contentCharSet = stack.findString("contentCharSet"); } } }