Android实现异步处理 -- HTTP请求为例

package com.chenjun.utils;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;


/**
 * 线程池辅助类，整个应用程序就只有一个线程池去管理线程。
 * 可以设置核心线程数、最大线程数、额外线程空状态生存时间，阻塞队列长度来优化线程池。
 * 下面的数据都是参考Android的AsynTask里的数据。
 * @author zet
 *
 */
public class ThreadPoolUtils {
    
    private ThreadPoolUtils(){
        
    }
    
    //线程池核心线程数
    private static int CORE_POOL_SIZE = 5;
    
    //线程池最大线程数
    private static int MAX_POOL_SIZE = 100;
    
    //额外线程空状态生存时间
    private static int KEEP_ALIVE_TIME = 10000;
    
    //阻塞队列。当核心线程都被占用，且阻塞队列已满的情况下，才会开启额外线程。
    private static BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<Runnable>(
            10);
    
    //线程工厂
    private static ThreadFactory threadFactory = new ThreadFactory() {
        private final AtomicInteger integer = new AtomicInteger();

        @Override
        public Thread newThread(Runnable r) {
            return new Thread(r, "myThreadPool thread:" + integer.getAndIncrement());
        }
    };
    
    //线程池
    private static ThreadPoolExecutor threadPool;
    
    static {
        threadPool = new ThreadPoolExecutor(CORE_POOL_SIZE,
                MAX_POOL_SIZE, KEEP_ALIVE_TIME, TimeUnit.SECONDS, workQueue,
                threadFactory);
    }
    
    
    /**
     * 从线程池中抽取线程，执行指定的Runnable对象
     * @param runnable
     */
    public static void execute(Runnable runnable){
        threadPool.execute(runnable);
    }

}

package com.chenjun.network.http;

import org.apache.http.HttpVersion;
import org.apache.http.client.HttpClient;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.protocol.HTTP;


/**
 * 辅助类，为整个应用程序提供唯一的一个HttpClient对象。
 * 这个对象有一些初始化的属性连接属性，这些属性可以被HttpGet、HttpPost的属性覆盖
 * @author zet
 *
 */
public class HttpClientHelper {
    private static HttpClient httpClient;
    
    private HttpClientHelper(){
        
    }
    
    public static synchronized HttpClient getHttpClient(){
        if(null == httpClient){
            //初始化工作
            HttpParams params = new BasicHttpParams();
            
            HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
            HttpProtocolParams.setContentCharset(params, HTTP.DEFAULT_CONTENT_CHARSET);
            HttpProtocolParams.setUseExpectContinue(params, true);
            
            
            //设置连接管理器的超时
            ConnManagerParams.setTimeout(params, 1000);
            
            //设置连接超时
            HttpConnectionParams.setConnectionTimeout(params, 5000);
            //设置Socket超时
            HttpConnectionParams.setSoTimeout(params, 10000);
            
            SchemeRegistry schReg = new SchemeRegistry();
            schReg.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
            schReg.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 80));
            
            ClientConnectionManager conManager = new ThreadSafeClientConnManager(params, schReg);
            
            httpClient = new DefaultHttpClient(conManager, params);
        }
        
        return httpClient;
    }
}

package com.chenjun.httpdemo;

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Toast;

import com.chenjun.asynctask.DownloadImageTask;
import com.chenjun.network.http.HttpClientHelper;
import com.chenjun.utils.ThreadPoolUtils;

public class HttpDemoActivity extends Activity {
    private static final int START_DOWNLOAD_MESSAGE = 0x01;
    private static final int FINISH_DOWNLOAD_MESSAGE = 0x02;
    private static final int ERROR_DOWNLOAD_MESSAGE = 0x03;
    
    private Handler myHandler;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        myHandler = new MyHandler();
        ThreadPoolUtils.execute(new MyRunnable());
    }
    private class MyRunnable implements Runnable{
        @Override
        public void run() {
            
            HttpGet httpGet = new HttpGet("http://www.sina.com.cn");
            
            //为这个HttpGet设置一些特定的属性，别的属性沿用HttpClient
            HttpParams params = new BasicHttpParams();
            HttpConnectionParams.setConnectionTimeout(params, 60000);
            httpGet.setParams(params);
            
            myHandler.sendEmptyMessage(START_DOWNLOAD_MESSAGE);
            
            try {
                
                HttpResponse httpResponse = HttpClientHelper.getHttpClient().execute(httpGet);;
                
                byte[] bytes = EntityUtils.toByteArray(httpResponse.getEntity());
                //在大多数情况下，这个下载下来的是XML或者Json。应该解析完组装成对象再放置到Message中。
                //这里简单起见，直接变成字符串打印了
                String result = new String(bytes);
                
                Message msg = myHandler.obtainMessage();
                msg.what = FINISH_DOWNLOAD_MESSAGE;
                msg.obj = result;
                
                myHandler.sendMessage(msg);
                
            } catch (Exception ex){
                ex.printStackTrace();
                myHandler.sendEmptyMessage(ERROR_DOWNLOAD_MESSAGE);
            }
        }
    }
    
    private class MyHandler extends Handler{
        @Override
        public void dispatchMessage(Message msg) {
            switch(msg.what){
            case START_DOWNLOAD_MESSAGE:
                Toast.makeText(HttpDemoActivity.this, "开始下载", Toast.LENGTH_SHORT).show();
                break;
            case FINISH_DOWNLOAD_MESSAGE:
                Toast.makeText(HttpDemoActivity.this, "下载成功", Toast.LENGTH_SHORT).show();
                
                //简单起见，直接输出了。
                System.out.println(msg.obj);
                break;
            case ERROR_DOWNLOAD_MESSAGE:
                Toast.makeText(HttpDemoActivity.this, "下载失败", Toast.LENGTH_SHORT).show();
                break;
            default:
                System.out.println("nothing to do");
                break;
            }
        }
    }
}