Android之用Handler实现主线程和子线程互相通信以及子线程和子线程之间的通信

1、上代码

activity_main.xml文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.handler.MainActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ParentToChile" />
    <Button
        android:layout_below="@+id/button1"
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ChileToParent" />
    <Button
        android:layout_below="@+id/button2"
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ChileToChile" />

</RelativeLayout>

MainActivity.java文件

package com.example.handler;

import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends ActionBarActivity {

public static final String TAG = "HandlerTest";

public Button mButtonPtoC;
public Button mButtonCtoP;
public Button mButtonCtoC;

public Handler mHandlerCToP = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch(msg.what) {
case 0:
Log.d(TAG, "mHandlerCToP msg.what is 0");
break;
default:
break;
}
}
};
public Handler mHandlerPToc = null;
public Handler mHandlerCtoC = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);
mButtonPtoC = (Button)findViewById(R.id.button1);
mButtonCtoP = (Button)findViewById(R.id.button2);
mButtonCtoC = (Button)findViewById(R.id.button3);

startChileThread("mHandlerPToc");
startChileThread("mHandlerCtoC");

mButtonPtoC.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
new Thread(new Runnable(){
@Override
public void run() {
mHandlerCToP.sendEmptyMessage(0);
}
}).start();
}
});

mButtonCtoP.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
mHandlerPToc.sendEmptyMessage(0);
}
});

mButtonCtoC.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
new Thread(new Runnable(){
@Override
public void run() {
mHandlerCtoC.sendEmptyMessage(0);
}
}).start();
}
});
}

//开启一根线程
public void startChileThread(final String type) {
new Thread(new Runnable(){
@Override
public void run() {
if (Looper.myLooper() == null) {
Log.d(TAG, "Looper.myLooper() is  null");
Looper.prepare();
}
else {
Log.d(TAG, "Looper.myLooper() is not null");
}
if ("mHandlerPToc".equals(type)) {
mHandlerPToc = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch(msg.what) {
case 0:
Log.d(TAG, "mHandlerPToc msg.what is 0");
break;
default:
break;
}
}
};
} else if ("mHandlerCtoC".equals(type)) {
mHandlerCtoC = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch(msg.what) {
case 0:
Log.d(TAG, "mHandlerCtoC msg.what is 0");
break;
default:
break;
}
}
};
} 
Looper.loop();
}
}).start();
}
}

3个按钮分别是子线程向主线程发消息、主线程向子线程发消息、子线程和子线程发消息

2、运行结果

控制台打印

3、总结

后面还会讲HandlerThread 实现子线程和子线程之间的通信，然后还有讲解Handler源码分析

1、上代码

2、运行结果

3、总结

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