com.google.wave.api.robot.HttpRobotConnection.java Source code

Introduction

Here is the source code for com.google.wave.api.robot.HttpRobotConnection.java

Source

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.wave.api.robot;

import com.google.common.base.Charsets;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.JdkFutureAdapters;
import com.google.common.util.concurrent.ListenableFuture;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;

import java.io.IOException;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;

/**
 * A {@link RobotConnection} that uses Apache's {@code HTTP Client} for
 * communicating with the robot.
 *
 */
public class HttpRobotConnection implements RobotConnection {

    /** A user agent client that can execute HTTP methods. */
    private final HttpClient httpClient;

    /** An executor to submit tasks asynchronously. */
    private final ExecutorService executor;

    /**
     * Constructor.
     *
     * @param client the client for executing HTTP methods.
     * @param executor the executor for submitting tasks asynchronously.
     */
    public HttpRobotConnection(HttpClient client, ExecutorService executor) {
        this.httpClient = client;
        this.executor = executor;
    }

    @Override
    public String get(String url) throws RobotConnectionException {
        GetMethod method = new GetMethod(url);
        return fetch(url, method);
    }

    @Override
    public ListenableFuture<String> asyncGet(final String url) {
        return JdkFutureAdapters.listenInPoolThread(executor.submit(new Callable<String>() {
            @Override
            public String call() throws RobotConnectionException {
                return get(url);
            }
        }));
    }

    @Override
    public String postJson(String url, String body) throws RobotConnectionException {
        PostMethod method = new PostMethod(url);
        try {
            method.setRequestEntity(
                    new StringRequestEntity(body, RobotConnection.JSON_CONTENT_TYPE, Charsets.UTF_8.name()));
            return fetch(url, method);
        } catch (IOException e) {
            String msg = "Robot fetch http failure: " + url + ": " + e;
            throw new RobotConnectionException(msg, e);
        }
    }

    @Override
    public ListenableFuture<String> asyncPostJson(final String url, final String body) {
        return JdkFutureAdapters.listenInPoolThread(executor.submit(new Callable<String>() {
            @Override
            public String call() throws RobotConnectionException {
                return postJson(url, body);
            }
        }));
    }

    /**
     * Fetches the given URL, given a method ({@code GET} or {@code POST}).
     *
     * @param url the URL to be fetched.
     * @param method the method to fetch the URL, can be {@code GET} or
     *     {@code POST}.
     * @return the content of the URL.
     *
     * @throws RobotConnectionException if there is a problem fetching the URL,
     *     for example, if the response code is not HTTP OK (200).
     */
    private String fetch(String url, HttpMethod method) throws RobotConnectionException {
        try {
            int statusCode = httpClient.executeMethod(method);
            return RobotConnectionUtil.validateAndReadResponse(url, statusCode, method.getResponseBodyAsStream());
        } catch (IOException e) {
            String msg = "Robot fetch http failure: " + url + ".";
            throw new RobotConnectionException(msg, e);
        } finally {
            method.releaseConnection();
        }
    }
}