Handler总结

一、整体工程图

二、activity_handler.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical">

	<Button android:text="Handler Lab1" android:id="@+id/buttonHandlerLab1" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab2" android:id="@+id/buttonHandlerLab2" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab3" android:id="@+id/buttonHandlerLab3" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab4.1" android:id="@+id/buttonHandlerLab4_1" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab4.2" android:id="@+id/buttonHandlerLab4_2" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab5.1" android:id="@+id/buttonHandlerLab5_1" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
	<Button android:text="Handler Lab5.2" android:id="@+id/buttonHandlerLab5_2" android:layout_width="fill_parent" android:layout_height="wrap_content"></Button>
</LinearLayout>

三、HandlerActivity.java

package com.jltxgcy.handlerdemo;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Toast;
import android.os.Process;

public class HandlerActivity extends Activity {
	private static final String TAG="jltxgcy";
	private final String HANDLER_KEY = "jltxgcy"  ;
	private Handler lab1Handler1 ;
	private Handler lab1Handler2 ;
	private Handler lab2Handler  ;
	private Handler lab3Handler;
	private Handler lab4Handler;
	private Handler lab5_1Handler = new Handler();
	private Handler lab5_2Handler;
	private Looper mLooper;
	private String result;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_handler);
    	lab1Handler2 = new Handler(){

			@Override
			public void handleMessage(Message msg) {
				super.handleMessage(msg);
				Toast.makeText(HandlerActivity.this, "[Main Thread]Handler2 Get the message: "+msg.getData().getString(HANDLER_KEY), 5000).show()  ;
			}

		} ;
		lab1Handler1 = new Handler(){

			@Override
			public void handleMessage(Message msg) {
				super.handleMessage(msg);
				result=msg.getData().getString(HANDLER_KEY);
				Toast.makeText(HandlerActivity.this, "[Main Thread]Handler1 Get the message: "+msg.getData().getString(HANDLER_KEY), 5000).show()  ;
			}

		} ;

		//Handler Lab1
		findViewById(R.id.buttonHandlerLab1).setOnClickListener(new OnClickListener(){

			@Override
			public void onClick(View v) {
				new Thread(new Runnable(){

					@Override
					public void run() {

						lab1Handler1.sendMessage(defineNewMessage("Lab1")) ;
						//try to use mainHanlder2 to send meesage and receive .
						//mainHandler2.sendMessage(defineNewMessage("Lab1")) ;

					}

				}).start();

			}

		}) ;

		findViewById(R.id.buttonHandlerLab2).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				new Thread(new Runnable(){

					@Override
					public void run() {
						lab2Handler = new Handler(Looper.getMainLooper())
						{

							@Override
							public void handleMessage(Message msg) {
								// TODO Auto-generated method stub
								super.handleMessage(msg);
								Log.d(TAG, "Get the message: "+msg.getData().getString(HANDLER_KEY)+" by Child Thread Handler")  ;
							}

						};
						lab2Handler.sendMessage(defineNewMessage("Lab2")) ;
						lab3Handler.sendMessage(defineNewMessage("Lab3")) ;

					}

				}).start() ;

			}
		});

		findViewById(R.id.buttonHandlerLab3).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				new Thread(new Runnable(){

					@Override
					public void run() {
						// TODO Auto-generated method stub
						Looper.prepare();
						lab3Handler = new Handler(){

							@Override
							public void handleMessage(Message msg) {
								// TODO Auto-generated method stub
								super.handleMessage(msg);
								Log.d(TAG, "Get the message from "+msg.getData().getString(HANDLER_KEY)+" by Child Thread Handler")  ;
							}
						} ;
						Looper.loop();
					}

				}).start() ;

			}
		});

		findViewById(R.id.buttonHandlerLab4_1).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				HandlerThread thread = new HandlerThread("ServiceStartArguments",
			            Process.THREAD_PRIORITY_BACKGROUND);
			    thread.start();

			    // Get the HandlerThread's Looper and use it for our Handler
			    mLooper = thread.getLooper();
			    lab4Handler = new Handler(mLooper){
			    	@Override
					public void handleMessage(Message msg) {
						// TODO Auto-generated method stub
						super.handleMessage(msg);
			        	Log.d(TAG, "Start message "+msg.getData().getString(HANDLER_KEY)+" by Child Thread Handler")  ;
			        	try {
							Thread.sleep(5*1000);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
			        	Log.d(TAG, "Finish message "+msg.getData().getString(HANDLER_KEY)+" by Child Thread Handler");
					}
			    };
				lab4Handler.sendMessage(defineNewMessage("Lab4.1")) ;
				lab4Handler.sendMessage(defineNewMessage("Lab4.2")) ;

			}
		});

		findViewById(R.id.buttonHandlerLab4_2).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				lab4Handler.removeMessages(1);

			}
		});

		findViewById(R.id.buttonHandlerLab5_1).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				lab5_1Handler.postDelayed(new MyRunnable(), 2000);
				Log.d(TAG, ""+Thread.currentThread().getId());
			}
		});

		findViewById(R.id.buttonHandlerLab5_2).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				HandlerThread handlerThread = new HandlerThread("myHandlerThread");
		        handlerThread.start();
		        lab5_2Handler = new Handler(handlerThread.getLooper());
		        lab5_2Handler.post(new MyRunnable());
		        Log.d(TAG,""+Thread.currentThread().getId());
			}
		});
    }

    private class MyRunnable implements Runnable {
        public void run() {
        	Log.d(TAG, "Runnable---The Thread is running");
            Log.d(TAG, ""+Thread.currentThread().getId());
        }
    }  

    private Message defineNewMessage(String messageContent)
	{
		Message returnMsg = new Message() ;
		Bundle data = new Bundle() ;
		data.putString(HANDLER_KEY, messageContent)  ;
		returnMsg.setData(data)  ;
		returnMsg.what=1;
		return returnMsg ;
	}
}

四、解析

Handler Lab1，接受消息的Handler在主线程中定义，而且处理消息也在主线程中。发送消息在子线程中。

Handler Lab2，接受消息的Handler在子线程中定义，而处理消息却在主线程中。发送消息在子线程中。

Handler Lab3，接受消息的Handler在子线程中定义，而且处理消息也在子线程中。发送消息在主线程中。

Hander  Lab4_1，接受消息的Handler在主线程中定义，而处理消息却在子线程中。发送消息在主线程中。

Hander  Lab4_2，连续发送两条信息，结果如下，说明是一条信息结束后，才处理另一个信息。

如果在发送第一个消息没有Finish前，按下Hander  Lab4_2，那么第一个消息不会取消，第二个消息会取消。

Hander  Lab5_1，延迟2秒钟，开启run中的方法。结果显示如下，说明没有开启新的线程。

Hander  Lab5_2，结果显示如下，这回开启了新的线程。

1、Hander子线程用于每隔多长时间，或者完成一项任务向主线程发送消息，主线程接受消息后，更新UI。

2、Hander主线程负责向子线程发送消息，子线程接受消息后开始下载。

3、postDelay用于比如闹钟要隔几分钟后启动。

五、Message

获取Message的两种方式，第一种比较易读，第二种比较简洁。

          1、Message msg =new Message();
                msg.arg1=x;
                msg.arg2=x;
                msg.obj=x;
                msg.replyTo=x;
                msg.what=x;
                msg.setData(Bundle bundle);
          2、Message msg =Handler.obtain(Handler h, int what, int arg1, int arg2, Object obj);
                msg.replyTo=x;
		              msg.setData(Bundle bundle);