handler和message传值两例

时间 2019-12-19

标签 handler message 两例繁體版

原文原文链接

程序效果：为了显示如何用message传值的简单例子 html

例1，点击按钮，持续显示当前系统时间（bundle传值，耗时，效率低） java

例2，点击按钮，progressbar持续前进（message方法传值，效率高，但只能传整型int和对象object） android

例1，主activity app

[java] view plain copy

package com.song;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class C91_HandlerActivity extends Activity {
/** Called when the activity is first created. */
TextView textview;
Button button;
MyThread mythread;
Thread thread;
MyHandler handler;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
textview=(TextView)findViewById(R.id.textview);
button=(Button)findViewById(R.id.button);
handler=new MyHandler();
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mythread=new MyThread();
thread=new Thread(mythread);
thread.start();
}
});
}
class MyHandler extends Handler
{
//接受message的信息
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
if(msg.what==1)
{
textview.setText(msg.getData().getString("time"));
}
}
}
class MyThread implements Runnable
{
@Override
public void run() {
// TODO Auto-generated method stub
while(true)
{
try {
Thread.sleep(1000);
String time=new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(new Date());
System.out.println(time);
Message message=new Message();
Bundle bundle=new Bundle();
bundle.putString("time", time);
message.setData(bundle);//bundle传值，耗时，效率低
handler.sendMessage(message);//发送message信息
message.what=1;//标志是哪一个线程传数据
//message有四个传值方法，
//两个传int整型数据的方法message.arg1，message.arg2
//一个传对象数据的方法message.obj
//一个bandle传值方法
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}

布局文件

[html] view plain copy

<?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:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="开始"
android:id="@+id/button"/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="20dp"
android:textStyle="bold"
android:id="@+id/textview"/>
</LinearLayout>

例2，主activity

[java] view plain copy

package com.song;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
public class C92_Handler2Activity extends Activity {
/** Called when the activity is first created. */
Button button;
ProgressBar bar;
MyThread mythread;
Thread thread;
MyHandler handler;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button=(Button)findViewById(R.id.button);
bar=(ProgressBar)findViewById(R.id.bar);
handler=new MyHandler();
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mythread=new MyThread();
thread=new Thread(mythread);
thread.start();
}
});
}
class MyHandler extends Handler
{
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
if(msg.what==1)
{
System.out.println(msg.arg1+"handle");
bar.setProgress(msg.arg1);
}
}
}
class MyThread implements Runnable
{
int pro=0;
@Override
public void run() {
// TODO Auto-generated method stub
while(true)
{
try {
Thread.sleep(1000);
pro=bar.getProgress()+1;
bar.setProgress(pro);
System.out.println(pro+"thread");
Message message=new Message();
message.arg1=pro;
message.what=1;
handler.sendMessage(message);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}

布局文件

[html] view plain copy

<?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:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/button"
android:text="开始"
/>
<ProgressBar android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/bar"
style="@android :style/Widget.ProgressBar.Horizontal"
/>
</LinearLayout>

显示效果