Android：ANR、线程间通讯、Handler、Message

场景：点击按钮1进行下载，显示进度条进度变化，10秒后下载完成，进度条消失；点击按钮2完成更新，出现转动进度条，5秒后更新完毕进度条消失。

public class MainActivity extends Activity implements OnClickListener
{
    TextView textView = null;
    private ProgressBar mProgress_yuan;
    private ProgressBar mProgress_jindu;
    private final int MSG_WHAT_DOWNLOAD = 1;
    private final int MSG_WHAT_UPDATE = 2;
    private final int MSG_WHAT_PROGRESS = 3;
                  
    private Handler mHandler = new Handler()// Handler运行于main线程,在main线程接收消息
    {
        @Override
        public void handleMessage(Message msg)// 重写handleMessage方法
        {
            switch (msg.what)
            {
            case MSG_WHAT_DOWNLOAD:
                Data data = (Data) msg.obj;
                textView.setText(data.toString());
                mProgress_jindu.setVisibility(View.GONE);// 下载完成后，进度条消失
                break;
                          
            case MSG_WHAT_UPDATE:
                String str = (String) msg.obj;
                textView.setText(str);
                mProgress_yuan.setVisibility(View.GONE);// 更新完毕后，圆形进度框消失
                break;
            case MSG_WHAT_PROGRESS:
                int arg = msg.arg1;
                mProgress_jindu.setProgress(arg);// 每次接收消息，更新进度条
                break;
                          
            default:
                break;
            }
        }
    };
                  
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
                      
        findViewById(R.id.button1).setOnClickListener(this);
        findViewById(R.id.button2).setOnClickListener(this);
        textView = (TextView) findViewById(R.id.textView1);
        mProgress_yuan = (ProgressBar) findViewById(R.id.progressBar1);
        mProgress_jindu = (ProgressBar) findViewById(R.id.progressBar2);
    }
                  
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
                  
    @Override
    public void onClick(View v)
    {
        switch (v.getId())
        {
        case R.id.button1:
            btn1Click();
            break;
        case R.id.button2:
            btn2Click();
            break;
                      
        default:
            break;
        }
    }
                  
    private void btn1Click()// 点击下载，10秒后下载完成,进度条消失
    {
        mProgress_jindu.setVisibility(View.VISIBLE);// 点击时进度条显示（xml设置默认隐藏）
        new Thread()
        {
            @Override
            public void run()
            {
                Message message = new Message();
                message.what = MSG_WHAT_DOWNLOAD; // 设置标识
                message.obj = download();// 将返回结果赋给msg,调用下载方法时同时发消息更新进度条
                mHandler.sendMessage(message);// 通过Handler传递msg
            }
        }.start();
                      
    }
                  
    private void btn2Click()// 点击更新，圆形进度条转动,3秒后更新完成，进度条消失
    {
        mProgress_yuan.setVisibility(View.VISIBLE);
        new Thread()
        {
            @Override
            public void run()
            {
                try
                {
                    Thread.sleep(3000);
                    String str = update();
                                  
                    //Message msg = mHandler.obtainMessage(what, obj)
                    //下面部分可以采用上面的方法优化
                    Message msg = new Message();
                    msg.what = MSG_WHAT_UPDATE;
                    msg.obj = str;
                    mHandler.sendMessage(msg);
                }
                catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
            }
        }.start();
    }
                  
    private Data download()
    {
        for (int i = 0; i < 10; i++)// 模拟下载进度过程
        {
            //Message msg = new Message();
            Message msg = mHandler.obtainMessage();//从系统的资源池获取复用msg，避免重复创建msg对象
            msg.what = MSG_WHAT_PROGRESS;
            msg.arg1 = i * 10;
            mHandler.sendMessage(msg);// 每次进度发消息给main线程更新进度条
            try
            {
                Thread.sleep(1000);// 10秒后下载完成
            }
            catch (InterruptedException e)
            {
                e.printStackTrace();
            }
        }
        Data data = new Data("下载完成!", 12);
        return data;
    }
                  
    private String update()
    {
        return "更新完成!";
    }
                  
    class Data
    {
        String name;
        int num;
                      
        public Data(String name, int num)
        {
            super();
            this.name = name;
            this.num = num;
        }
                      
        @Override
        public String toString()
        {
            return "data [name=" + name + ", num=" + num + "]";
        }
                      
    }
}

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