Android中Handler和HandlerThread的使用

Android中熟练和正确的使用Handler和HandlerThread是非常必要的，这里是一些简单的示例，包括Handler和HandlerThread与主线程的通信，欢迎拍砖。

package com.glowgeniuses.allforone;

import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.os.SystemClock;
import android.support.design.widget.FloatingActionButton;
import android.util.Log;
import android.view.View;
import android.support.v7.app.AppCompatActivity;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import java.lang.ref.WeakReference;
import java.util.Date;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private Button btnMainTest;
private ImageView ivMainTest;
private TextView tvMainTest;
private RelativeLayout rlMainTest;
private ProgressBar pbMainTest;

// 主线程的Handler
private EventHandler mainThreadHandler;
// 非主线程的Handler
private EventHandler otherThreadHandler;
// 工作线程
private HandlerThread handlerThread;

private Runnable updateProgress;

private Toast toast;

private final static int MSG_1001 = 1001;
private final static int MSG_1002 = 1002;
private final static int MSG_1003 = 1003;
private final static int MSG_1004 = 1004;
private final static int MSG_1005 = 1005;
private final static int MSG_1006 = 1006;

private int progress = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ivMainTest = (ImageView) findViewById(R.id.ivMainTest);
btnMainTest = (Button) findViewById(R.id.btnMainTest);
tvMainTest = (TextView) findViewById(R.id.tvMainTest);
rlMainTest = (RelativeLayout) findViewById(R.id.rlMainTest);
pbMainTest = (ProgressBar) findViewById(R.id.pbMainTest);

if (pbMainTest != null) {
pbMainTest.setMax(2000);
}

ivMainTest.setOnClickListener(this);
btnMainTest.setOnClickListener(this);
tvMainTest.setOnClickListener(this);
rlMainTest.setOnClickListener(this);

// 初始化主线程Handler
Looper looper;
if ((looper = Looper.myLooper()) != null) {
mainThreadHandler = new EventHandler(this, looper);
} else if ((looper = Looper.getMainLooper()) != null) {
mainThreadHandler = new EventHandler(this, looper);
} else {
mainThreadHandler = null;
}

// 其他线程
handlerThread = new HandlerThread("HandlerThread");
handlerThread.start();
// 非主线程的handler post的runnable在自线程跑
otherThreadHandler = new EventHandler(this, handlerThread.getLooper());
updateProgress = new Runnable() {
@Override
public void run() {
progress = progress + 1;
Message msg1005 = otherThreadHandler.obtainMessage(MSG_1005, progress);
otherThreadHandler.sendMessage(msg1005);

// 模拟耗时操作
otherThreadHandler.postDelayed(updateProgress, 10);
}
};
otherThreadHandler.post(updateProgress);
}

@Override
protected void onDestroy() {
if (mainThreadHandler != null) {
mainThreadHandler.removeCallbacksAndMessages(null);
}
if (otherThreadHandler != null) {
otherThreadHandler.removeCallbacksAndMessages(null);
}
if (handlerThread != null) {
handlerThread.quit();
}
super.onDestroy();
}

@Override
public void onClick(View view) {
if (mainThreadHandler == null) {
return;
}
switch (view.getId()) {
case R.id.tvMainTest:
// message 不带参数
Message msg1001 = mainThreadHandler.obtainMessage(MSG_1001);
mainThreadHandler.sendMessage(msg1001);
// 也可以写成 msg1001.sendToTarget();
break;
case R.id.ivMainTest:
// message 中带obj参数 非主线程
Message msg1002 = otherThreadHandler.
obtainMessage(MSG_1002, new Date().toLocaleString());
msg1002.sendToTarget();
break;
case R.id.btnMainTest:
// message 延迟3秒发送
Message msg1003 = mainThreadHandler.obtainMessage(MSG_1003);
mainThreadHandler.sendMessageDelayed(msg1003, 3000);
break;
case R.id.rlMainTest:
// message 带上两个简单int参数和obj参数
Message msg1004 = mainThreadHandler.
obtainMessage(MSG_1004, 1, 2, new Date().toLocaleString());
// 指定一个时间发送 SystemClock.uptimeMillis() 当前开机时间
mainThreadHandler.sendMessageAtTime(msg1004, SystemClock.uptimeMillis() + 2000);
break;
}
}

private void showToast(String tip) {
if (toast == null) {
toast = Toast.makeText(this, tip, Toast.LENGTH_SHORT);
toast.show();
} else {
toast.cancel();
toast = Toast.makeText(this, tip, Toast.LENGTH_SHORT);
toast.show();
}
}

/**
* 处理事务
*
* @param msg 消息
*/
private void handlerMessage(Message msg) {
if (msg == null) {
return;
}
switch (msg.what) {
case MSG_1001:
showToast("空消息");
break;
case MSG_1002:
showToast((String) msg.obj);
//这条消息来自子线程,再与主线程通信
mainThreadHandler.sendMessage(
mainThreadHandler.obtainMessage(MSG_1006, "来自子线程"));
break;
case MSG_1003:
showToast("延迟3秒");
break;
case MSG_1004:
showToast(msg.arg1 + " " + msg.arg2 + " " +
msg.obj.toString());
break;
case MSG_1005:
pbMainTest.setProgress((Integer) msg.obj);
break;
case MSG_1006:
tvMainTest.setText((String) msg.obj + new Date().toLocaleString());
break;
}
}

/**
* Handler
*/
private static class EventHandler extends Handler {
// 防止Handler Leak
private final WeakReference<MainActivity> weakReference;

public EventHandler(MainActivity activity, Looper Looper) {
super(Looper);
weakReference = new WeakReference<MainActivity>(activity);
}

@Override
public void handleMessage(Message msg) {
MainActivity activity = weakReference.get();
if (activity == null) {
return;
}
if (msg.what != MSG_1005) {
// 显示其处理的线程id
Log.d("MainActivity",
Thread.currentThread().getId() + " " + msg.what);
}
// 事件分发
activity.handlerMessage(msg);
}
}
}