com.sangupta.jerry.util.ResponseUtils Maven / Gradle / Ivy

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/**
 *
 * jerry - Common Java Functionality
 * Copyright (c) 2012, Sandeep Gupta
 * 
 * http://www.sangupta/projects/jerry
 * 
 * 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 com.sangupta.jerry.util;

import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import com.sangupta.jerry.http.HttpStatusCode;

/**
 * Utility methods to work with {@link HttpServletResponse} object.
 * 
 * @author sangupta
 *
 */
public class ResponseUtils {
	
	/**
	 * Write the given response in UTF-8 encoding to the given {@link HttpServletResponse} object.
	 * 
	 * @param response the {@link HttpServletResponse} to write data to
	 * 
	 * @param data the data that needs to be written to the stream
	 * 
	 * @param mimeType the MIME type of the data being written
	 * 
	 * @throws IOException if something fails while writing to {@link HttpServletResponse}.
	 * 
	 * @throws NullPointerException if {@link HttpServletResponse} object is null
	 * 
	 */
	public static void sendResponse(HttpServletResponse response, String data, String mimeType) throws IOException {
		response.setContentType(mimeType);
		response.setStatus(HttpStatusCode.OK);
		response.setContentLength(data.length());
		response.setCharacterEncoding("UTF-8");
		response.getWriter().write(data);
	}

	/**
	 * Push the given data as a file to the client browser for downloading. The response is written in such
	 * a way so that the client browser displays a dailog for downloading the file.
	 * 
	 * @param response the {@link HttpServletResponse} object to write to
	 * 
	 * @param data the data that needs to be sent to client
	 * 
	 * @param fileName the filename to be used by browsers when displaying 'Save As' dialog
	 * 
	 * @param mimeType the MIME type of the data being written
	 * 
	 * @throws IOException if something fails when writing to {@link HttpServletResponse} object
	 * 
	 * @throws NullPointerException if {@link HttpServletResponse} object is null, or if
	 * data is null
	 * 
	 */
	public static void pushForUserDownload(HttpServletResponse response, String data, String fileName, String mimeType) throws IOException {
		setOnlyDownload(response, fileName);

		response.setContentType(mimeType + "; charset=UTF-8");
		response.setCharacterEncoding("UTF-8");
		response.setStatus(HttpServletResponse.SC_OK);
		
		ServletOutputStream stream = response.getOutputStream();
		byte[] bytes = data.getBytes("UTF-8");
		response.setContentLength(bytes.length);
		stream.write(bytes);
		stream.flush();
		stream.close();
	}

	/**
	 * Write the given byte array to the {@link HttpServletResponse} object asking the client
	 * browser to present a dialog to save the file. The MIME type used is application/octet-stream
	 * to allow for binary file downloads.
	 * 
	 * @param response the {@link HttpServletResponse} object to write to
	 * 
	 * @param bytes the bytes to write
	 * 
	 * @param fileName the file name to be presented to client browser
	 * 
	 * @throws IOException if something fails when writing to {@link HttpServletResponse} object
	 * 
	 * @throws NullPointerException if {@link HttpServletResponse} object is null
	 * 
	 */
	public static void pushForUserDownload(HttpServletResponse response, byte[] bytes, String fileName) throws IOException {
		setOnlyDownload(response, fileName);

		response.setContentType("application/octet-stream");
		response.setCharacterEncoding("UTF-8");
		response.setStatus(HttpServletResponse.SC_OK);
		
		ServletOutputStream stream = response.getOutputStream();
		response.setContentLength(bytes.length);
		stream.write(bytes);
		stream.flush();
		stream.close();
	}

	/**
	 * Make sure that IE8+ do not sniff for MIME when already
	 * specified in response.
	 * 
	 * Refer to http://blogs.msdn.com/b/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
	 * for more details.
	 * 
	 * @param repsonse the {@link HttpServletResponse} object to use
	 * 
	 * @throws NullPointerException if {@link HttpServletResponse} object is null
	 * 
	 */
	public static void sendNoSniff(HttpServletResponse repsonse) {
		repsonse.addHeader("X-Content-Type-Options", "nosniff");
	}
	
	/**
	 * Instruct the response to only allow file download, and not
	 * let it open directly in the client browser.
	 * 
	 * Refer to http://blogs.msdn.com/b/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
	 * for more details.
	 * 
	 * @param response the {@link HttpServletResponse} object to use
	 * 
	 * @param fileName the fileName to present to client browser for allowing download of file
	 * 
	 * @throws NullPointerException if {@link HttpServletResponse} object is null
	 * 
	 */
	public static void setOnlyDownload(HttpServletResponse response, String fileName) {
		response.addHeader("X-Download-Options", "noopen");
		response.addHeader("Content-Disposition", "attachment; filename=" + fileName);
	}
}