[Android]简单的Handler样例，通过线程队列和消息队列操作一个ProgressBar
Handler主要用于异步消息的处理。这里点击了按钮之后在run方法中设置message的alg1的值，每次通过sendMessage把message对象压入消息队列。在handleMessage方法中取出消息队列中的message对象，并设置progressBar的值，然后再把线程对象加入线程队列。这个循环一直运行到进度条走到头~~。
package com.example.prograssbarhandle;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ProgressBar;public class MainActivity extends Activity {private ProgressBar pb1=null;private Button bt1=null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); bt1=(Button)findViewById(R.id.but); pb1=(ProgressBar)findViewById(R.id.firstBar); pb1.setVisibility(View.VISIBLE); bt1.setOnClickListener(new bt1listener()); } class bt1listener implements OnClickListener{public void onClick(View arg0) {// TODO Auto-generated method stubhl1.post(run1);} } Handler hl1=new Handler() {@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stubpb1.setProgress(msg.arg1);hl1.post(run1);} }; Runnable run1=new Runnable() { int i=0;public void run() {// TODO Auto-generated method stubi+=10;//得到一个消息对象Message msg=hl1.obtainMessage();msg.arg1=i;try{Thread.sleep(1000);}catch(InterruptedException e){e.printStackTrace();}if(i>=100){i=0;pb1.setProgress(i);//bt1.setText("dawda");hl1.removeCallbacks(run1);return;}hl1.sendMessage(msg);} }; @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; }}
<LinearLayout 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:orientation="vertical"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/hello_world" tools:context=".MainActivity" /> <Button android:id="@+id/but" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="start" /> <ProgressBar android:layout_width="200dp" android:layout_height="wrap_content" android:id="@+id/firstBar" style="?android:attr/progressBarStyleHorizontal" /></LinearLayout>
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