| /* |
| * Copyright (C) 2009 Google Inc. All rights reserved. |
| * |
| * 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.google.polo.wire.json; |
| |
| import com.google.polo.exception.PoloException; |
| import com.google.polo.json.JSONException; |
| import com.google.polo.json.JSONObject; |
| import com.google.polo.pairing.PairingContext; |
| import com.google.polo.pairing.PoloUtil; |
| import com.google.polo.pairing.message.PoloMessage; |
| import com.google.polo.pairing.message.PoloMessage.PoloMessageType; |
| import com.google.polo.wire.PoloWireInterface; |
| |
| import java.io.DataInputStream; |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.OutputStream; |
| |
| /** |
| * A {@link PoloWireInterface} which uses JavaScript Object Notation (JSON) for |
| * the message representation. |
| * <p> |
| * Messages are streamed over the wire prepended with an integer which indicates |
| * the total length, in bytes, of the message which follows. The format of the |
| * message is JSON. |
| * <p> |
| * See {@link JsonMessageBuilder} for the underlying message translation |
| * implementation. |
| */ |
| public class JsonWireAdapter implements PoloWireInterface { |
| |
| /** |
| * The output coming from the peer. |
| */ |
| private final DataInputStream mInputStream; |
| |
| /** |
| * The input going to the peer. |
| */ |
| private final DataOutputStream mOutputStream; |
| |
| /** |
| * Constructor. |
| * |
| * @param input the {@link InputStream} from the peer |
| * @param output the {@link OutputStream} to the peer |
| */ |
| public JsonWireAdapter(InputStream input, OutputStream output) { |
| mInputStream = new DataInputStream(input); |
| mOutputStream = new DataOutputStream(output); |
| } |
| |
| /** |
| * Generates a new instance from a {@link PairingContext}. |
| * |
| * @param context the {@link PairingContext} |
| * @return the new instance |
| */ |
| public static JsonWireAdapter fromContext(PairingContext context) { |
| return new JsonWireAdapter(context.getPeerInputStream(), context |
| .getPeerOutputStream()); |
| } |
| |
| public PoloMessage getNextMessage() throws IOException, PoloException { |
| byte[] payloadLenBytes = new byte[4]; |
| mInputStream.readFully(payloadLenBytes); |
| long payloadLen = PoloUtil.intBigEndianBytesToLong(payloadLenBytes); |
| byte[] outerJsonBytes = new byte[(int) payloadLen]; |
| mInputStream.readFully(outerJsonBytes); |
| return parseOuterMessageString(new String(outerJsonBytes)); |
| } |
| |
| public PoloMessage parseOuterMessageString(String outerString) |
| throws PoloException { |
| JSONObject outerMessage; |
| try { |
| outerMessage = new JSONObject(outerString); |
| } catch (JSONException e) { |
| throw new PoloException("Error parsing incoming message", e); |
| } |
| return JsonMessageBuilder.outerJsonToPoloMessage(outerMessage); |
| } |
| |
| public PoloMessage getNextMessage(PoloMessageType type) throws IOException, |
| PoloException { |
| PoloMessage message = getNextMessage(); |
| if (message.getType() != type) { |
| throw new PoloException("Wrong message type (wanted " + type + ", got " |
| + message.getType() + ")"); |
| } |
| return message; |
| } |
| |
| public void sendErrorMessage(Exception exception) throws IOException { |
| try { |
| writeJson(JsonMessageBuilder.getErrorJson(exception)); |
| } catch (PoloException e) { |
| throw new IOException("Error sending error message"); |
| } |
| } |
| |
| public void sendMessage(PoloMessage message) throws IOException { |
| String outString; |
| JSONObject outerJson; |
| |
| try { |
| outerJson = JsonMessageBuilder.getOuterJson(message); |
| } catch (PoloException e) { |
| throw new IOException("Error generating message"); |
| } |
| |
| writeJson(outerJson); |
| } |
| |
| /** |
| * Writes a {@link JSONObject} to the output stream as a {@link String}. |
| * |
| * @param message the message to write |
| * @throws IOException on error generating the serialized message |
| */ |
| private void writeJson(JSONObject message) throws IOException { |
| byte[] outBytes = message.toString().getBytes(); |
| mOutputStream.write(PoloUtil.intToBigEndianIntBytes(outBytes.length)); |
| mOutputStream.write(outBytes); |
| } |
| |
| } |