001 // Copyright 2005 The Apache Software Foundation 002 // 003 // Licensed under the Apache License, Version 2.0 (the "License"); 004 // you may not use this file except in compliance with the License. 005 // You may obtain a copy of the License at 006 // 007 // http://www.apache.org/licenses/LICENSE-2.0 008 // 009 // Unless required by applicable law or agreed to in writing, software 010 // distributed under the License is distributed on an "AS IS" BASIS, 011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012 // See the License for the specific language governing permissions and 013 // limitations under the License. 014 015 package org.apache.tapestry.web; 016 017 import java.io.IOException; 018 import java.io.OutputStream; 019 import java.io.PrintWriter; 020 021 import org.apache.tapestry.util.ContentType; 022 023 /** 024 * Controls the response to the client, and specifically allows for creating the output stream (or 025 * print writer) to which content is sent. This is essentially a generic version of 026 * {@link javax.servlet.http.HttpServletResponse}. Some operations may be unsupported in some 027 * implementations (for example, the portlet implementation can't handle any of the setHeader 028 * methods). 029 * 030 * @author Howard M. Lewis Ship 031 * @since 4.0 032 */ 033 public interface WebResponse 034 { 035 /** 036 * Returns a output stream to which output should be sent. This method should only be invoked 037 * once on a response. 038 * 039 * @return the output stream, configured for the given type. 040 */ 041 042 public OutputStream getOutputStream(ContentType contentType) throws IOException; 043 044 /** 045 * Returns a {@link PrintWriter} to which output should be sent. This method should be invoked 046 * once on a response. A second call is expected to be so that an exception page can be 047 * rendered, and the underlying request data is reset. 048 */ 049 050 public PrintWriter getPrintWriter(ContentType contentType) throws IOException; 051 052 /** 053 * Encodes a URL, which adds information to the URL needed to ensure that the request triggered 054 * by the URL will be associated with the current session (if any). In most cases, the string is 055 * returned unchanged. 056 */ 057 058 public String encodeURL(String url); 059 060 /** 061 * Resets any buffered content. This may be used after an error to radically change what the 062 * output will be. 063 */ 064 065 public void reset(); 066 067 public void setContentLength(int contentLength); 068 069 /** 070 * Returns a value to be prefixed or suffixed with any client-side JavaScript elements 071 * (variables and function names) to ensure that they are unique with the context of the entire 072 * page. For servlets, this is the empty string. 073 */ 074 075 public String getNamespace(); 076 077 /** 078 * Sets a response header as a date. 079 * 080 * @param name 081 * the name of the header to set 082 * @param date 083 * the date value to set, in milliseconds since the epoch 084 */ 085 public void setDateHeader(String name, long date); 086 087 /** 088 * Sets a response header as a string. 089 * 090 * @param name 091 * the name of the header to set 092 * @param value 093 * the value for the named header 094 */ 095 096 public void setHeader(String name, String value); 097 098 /** 099 * Sets a response header with the given name and integer value. 100 * 101 * @param name 102 * the name of the header to set 103 * @param value 104 * the value for the named header 105 */ 106 public void setIntHeader(String name, int value); 107 108 /** 109 * Sets the status code for this response. 110 */ 111 public void setStatus(int status); 112 113 /** 114 * Sends an error response. 115 */ 116 117 public void sendError(int statusCode, String message) throws IOException; 118 }