Java tutorial
/* * Copyright 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. */ import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.util.Locale; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.ServletResponse; import javax.servlet.ServletResponseWrapper; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; /** * Implementation of <b>HttpServletResponseWrapper</b> that works with * the CompressionServletResponseStream implementation.. * * @author Amy Roh * @author Dmitri Valdin * @version $Revision: 1.3 $, $Date: 2004/03/18 16:40:33 $ */ public class CompressionServletResponseWrapper extends HttpServletResponseWrapper { // ----------------------------------------------------- Constructor /** * Calls the parent constructor which creates a ServletResponse adaptor * wrapping the given response object. */ public CompressionServletResponseWrapper(HttpServletResponse response) { super(response); origResponse = response; if (debug > 1) { System.out.println("CompressionServletResponseWrapper constructor gets called"); } } // ----------------------------------------------------- Instance Variables /** * Original response */ protected HttpServletResponse origResponse = null; /** * Descriptive information about this Response implementation. */ protected static final String info = "CompressionServletResponseWrapper"; /** * The ServletOutputStream that has been returned by * <code>getOutputStream()</code>, if any. */ protected ServletOutputStream stream = null; /** * The PrintWriter that has been returned by * <code>getWriter()</code>, if any. */ protected PrintWriter writer = null; /** * The threshold number to compress */ protected int threshold = 0; /** * Debug level */ private int debug = 0; /** * Content type */ protected String contentType = null; // --------------------------------------------------------- Public Methods /** * Set content type */ public void setContentType(String contentType) { if (debug > 1) { System.out.println("setContentType to " + contentType); } this.contentType = contentType; origResponse.setContentType(contentType); } /** * Set threshold number */ public void setCompressionThreshold(int threshold) { if (debug > 1) { System.out.println("setCompressionThreshold to " + threshold); } this.threshold = threshold; } /** * Set debug level */ public void setDebugLevel(int debug) { this.debug = debug; } /** * Create and return a ServletOutputStream to write the content * associated with this Response. * * @exception IOException if an input/output error occurs */ public ServletOutputStream createOutputStream() throws IOException { if (debug > 1) { System.out.println("createOutputStream gets called"); } CompressionResponseStream stream = new CompressionResponseStream(origResponse); stream.setDebugLevel(debug); stream.setBuffer(threshold); return stream; } /** * Finish a response. */ public void finishResponse() { try { if (writer != null) { writer.close(); } else { if (stream != null) stream.close(); } } catch (IOException e) { } } // ------------------------------------------------ ServletResponse Methods /** * Flush the buffer and commit this response. * * @exception IOException if an input/output error occurs */ public void flushBuffer() throws IOException { if (debug > 1) { System.out.println("flush buffer @ CompressionServletResponseWrapper"); } ((CompressionResponseStream) stream).flush(); } /** * Return the servlet output stream associated with this Response. * * @exception IllegalStateException if <code>getWriter</code> has * already been called for this response * @exception IOException if an input/output error occurs */ public ServletOutputStream getOutputStream() throws IOException { if (writer != null) throw new IllegalStateException("getWriter() has already been called for this response"); if (stream == null) stream = createOutputStream(); if (debug > 1) { System.out.println("stream is set to " + stream + " in getOutputStream"); } return (stream); } /** * Return the writer associated with this Response. * * @exception IllegalStateException if <code>getOutputStream</code> has * already been called for this response * @exception IOException if an input/output error occurs */ public PrintWriter getWriter() throws IOException { if (writer != null) return (writer); if (stream != null) throw new IllegalStateException("getOutputStream() has already been called for this response"); stream = createOutputStream(); if (debug > 1) { System.out.println("stream is set to " + stream + " in getWriter"); } //String charset = getCharsetFromContentType(contentType); String charEnc = origResponse.getCharacterEncoding(); if (debug > 1) { System.out.println("character encoding is " + charEnc); } // HttpServletResponse.getCharacterEncoding() shouldn't return null // according the spec, so feel free to remove that "if" if (charEnc != null) { writer = new PrintWriter(new OutputStreamWriter(stream, charEnc)); } else { writer = new PrintWriter(stream); } return (writer); } public void setContentLength(int length) { } /** * Returns character from content type. This method was taken from tomcat. * @author rajo */ private static String getCharsetFromContentType(String type) { if (type == null) { return null; } int semi = type.indexOf(";"); if (semi == -1) { return null; } String afterSemi = type.substring(semi + 1); int charsetLocation = afterSemi.indexOf("charset="); if (charsetLocation == -1) { return null; } else { String afterCharset = afterSemi.substring(charsetLocation + 8); String encoding = afterCharset.trim(); return encoding; } } } /// the visibility of variables declared at class level and within methods. class HW { int j; // j is visible to both method1 and method 2 void method1() { double x; // x is visible only to method1 } void method2() { double y; // y is visible only to method2 } }