The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2007 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.webkit; |
| 18 | |
| 19 | import android.net.http.EventHandler; |
| 20 | import android.net.http.Headers; |
| 21 | import android.os.Handler; |
| 22 | import android.os.Message; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 23 | |
| 24 | import java.io.IOException; |
| 25 | import java.io.InputStream; |
| 26 | |
| 27 | |
| 28 | /** |
| 29 | * This abstract class is used for all content loaders that rely on streaming |
| 30 | * content into the rendering engine loading framework. |
| 31 | * |
| 32 | * The class implements a state machine to load the content into the frame in |
| 33 | * a similar manor to the way content arrives from the network. The class uses |
| 34 | * messages to move from one state to the next, which enables async. loading of |
| 35 | * the streamed content. |
| 36 | * |
| 37 | * Classes that inherit from this class must implement two methods, the first |
| 38 | * method is used to setup the InputStream and notify the loading framework if |
| 39 | * it can load it's content. The other method allows the derived class to add |
| 40 | * additional HTTP headers to the response. |
| 41 | * |
| 42 | * By default, content loaded with a StreamLoader is marked with a HTTP header |
| 43 | * that indicates the content should not be cached. |
| 44 | * |
| 45 | */ |
| 46 | abstract class StreamLoader extends Handler { |
| 47 | |
| 48 | public static final String NO_STORE = "no-store"; |
| 49 | |
| 50 | private static final int MSG_STATUS = 100; // Send status to loader |
| 51 | private static final int MSG_HEADERS = 101; // Send headers to loader |
| 52 | private static final int MSG_DATA = 102; // Send data to loader |
| 53 | private static final int MSG_END = 103; // Send endData to loader |
| 54 | |
| 55 | protected LoadListener mHandler; // loader class |
| 56 | protected InputStream mDataStream; // stream to read data from |
| 57 | protected long mContentLength; // content length of data |
| 58 | private byte [] mData; // buffer to pass data to loader with. |
| 59 | |
| 60 | /** |
| 61 | * Constructor. Although this class calls the LoadListener, it only calls |
| 62 | * the EventHandler Interface methods. LoadListener concrete class is used |
| 63 | * to avoid the penality of calling an interface. |
| 64 | * |
| 65 | * @param loadlistener The LoadListener to call with the data. |
| 66 | */ |
| 67 | StreamLoader(LoadListener loadlistener) { |
| 68 | mHandler = loadlistener; |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * This method is called when the derived class should setup mDataStream, |
| 73 | * and call mHandler.status() to indicate that the load can occur. If it |
| 74 | * fails to setup, it should still call status() with the error code. |
| 75 | * |
| 76 | * @return true if stream was successfully setup |
| 77 | */ |
| 78 | protected abstract boolean setupStreamAndSendStatus(); |
| 79 | |
| 80 | /** |
| 81 | * This method is called when the headers are about to be sent to the |
| 82 | * load framework. The derived class has the opportunity to add addition |
| 83 | * headers. |
| 84 | * |
| 85 | * @param headers Map of HTTP headers that will be sent to the loader. |
| 86 | */ |
| 87 | abstract protected void buildHeaders(Headers headers); |
| 88 | |
| 89 | |
| 90 | /** |
| 91 | * Calling this method starts the load of the content for this StreamLoader. |
| 92 | * This method simply posts a message to send the status and returns |
| 93 | * immediately. |
| 94 | */ |
| 95 | public void load() { |
| 96 | if (!mHandler.isSynchronous()) { |
| 97 | sendMessage(obtainMessage(MSG_STATUS)); |
| 98 | } else { |
| 99 | // Load the stream synchronously. |
| 100 | if (setupStreamAndSendStatus()) { |
| 101 | // We were able to open the stream, create the array |
| 102 | // to pass data to the loader |
| 103 | mData = new byte[8192]; |
| 104 | sendHeaders(); |
Patrick Scott | e82dc42 | 2009-04-29 10:21:57 -0400 | [diff] [blame] | 105 | while (!sendData() && !mHandler.cancelled()); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 106 | closeStreamAndSendEndData(); |
| 107 | mHandler.loadSynchronousMessages(); |
| 108 | } |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /* (non-Javadoc) |
| 113 | * @see android.os.Handler#handleMessage(android.os.Message) |
| 114 | */ |
| 115 | public void handleMessage(Message msg) { |
Dave Bort | 42bc2ff | 2009-04-13 15:07:51 -0700 | [diff] [blame] | 116 | if (WebView.DEBUG && mHandler.isSynchronous()) { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 117 | throw new AssertionError(); |
| 118 | } |
Patrick Scott | e82dc42 | 2009-04-29 10:21:57 -0400 | [diff] [blame] | 119 | if (mHandler.cancelled()) { |
| 120 | closeStreamAndSendEndData(); |
| 121 | return; |
| 122 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 123 | switch(msg.what) { |
| 124 | case MSG_STATUS: |
| 125 | if (setupStreamAndSendStatus()) { |
| 126 | // We were able to open the stream, create the array |
| 127 | // to pass data to the loader |
| 128 | mData = new byte[8192]; |
| 129 | sendMessage(obtainMessage(MSG_HEADERS)); |
| 130 | } |
| 131 | break; |
| 132 | case MSG_HEADERS: |
| 133 | sendHeaders(); |
| 134 | sendMessage(obtainMessage(MSG_DATA)); |
| 135 | break; |
| 136 | case MSG_DATA: |
| 137 | if (sendData()) { |
| 138 | sendMessage(obtainMessage(MSG_END)); |
| 139 | } else { |
| 140 | sendMessage(obtainMessage(MSG_DATA)); |
| 141 | } |
| 142 | break; |
| 143 | case MSG_END: |
| 144 | closeStreamAndSendEndData(); |
| 145 | break; |
| 146 | default: |
| 147 | super.handleMessage(msg); |
| 148 | break; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * Construct the headers and pass them to the EventHandler. |
| 154 | */ |
| 155 | private void sendHeaders() { |
| 156 | Headers headers = new Headers(); |
| 157 | if (mContentLength > 0) { |
| 158 | headers.setContentLength(mContentLength); |
| 159 | } |
| 160 | headers.setCacheControl(NO_STORE); |
| 161 | buildHeaders(headers); |
| 162 | mHandler.headers(headers); |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Read data from the stream and pass it to the EventHandler. |
| 167 | * If an error occurs reading the stream, then an error is sent to the |
| 168 | * EventHandler, and moves onto the next state - end of data. |
| 169 | * @return True if all the data has been read. False if sendData should be |
| 170 | * called again. |
| 171 | */ |
| 172 | private boolean sendData() { |
| 173 | if (mDataStream != null) { |
| 174 | try { |
| 175 | int amount = mDataStream.read(mData); |
| 176 | if (amount > 0) { |
| 177 | mHandler.data(mData, amount); |
| 178 | return false; |
| 179 | } |
| 180 | } catch (IOException ex) { |
| 181 | mHandler.error(EventHandler.FILE_ERROR, |
| 182 | ex.getMessage()); |
| 183 | } |
| 184 | } |
| 185 | return true; |
| 186 | } |
| 187 | |
| 188 | /** |
| 189 | * Close the stream and inform the EventHandler that load is complete. |
| 190 | */ |
| 191 | private void closeStreamAndSendEndData() { |
| 192 | if (mDataStream != null) { |
| 193 | try { |
| 194 | mDataStream.close(); |
| 195 | } catch (IOException ex) { |
| 196 | // ignore. |
| 197 | } |
| 198 | } |
| 199 | mHandler.endData(); |
| 200 | } |
| 201 | |
| 202 | } |