子线程控制ProgressDialog的可见性

最新推荐文章于 2018-06-24 14:43:10 发布

原创最新推荐文章于 2018-06-24 14:43:10 发布 · 308 阅读

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#Android #FP #thread #OS

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本文通过一个具体的Android应用实例，展示了如何使用Looper机制配合ProgressDialog组件实现异步加载效果。主要涉及Activity布局设置、按钮点击监听及子线程操作。

这个代码让我有点迷惑:


package com.example;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class Looper_07 extends Activity implements OnClickListener {
	private final int WC = LinearLayout.LayoutParams.WRAP_CONTENT;
	private final int FP = LinearLayout.LayoutParams.FILL_PARENT;
	private ProgressDialog progressDialog = null;
	public TextView tv;
	private Button btn, btn2;
	Thread th1;

	public void onCreate(Bundle icicle) {
		super.onCreate(icicle);
		LinearLayout layout = new LinearLayout(this);
		layout.setOrientation(LinearLayout.VERTICAL);

		btn = new Button(this);
		btn.setId(101);
		btn.setBackgroundResource(R.drawable.icon);
		btn.setText("test looper");
		btn.setOnClickListener(this);
		LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(100, 50);
		param.topMargin = 10;
		layout.addView(btn, param);

		btn2 = new Button(this);
		btn2.setId(102);
		btn2.setBackgroundResource(R.drawable.icon);
		btn2.setText("exit");
		btn2.setOnClickListener(this);
		layout.addView(btn2, param);

		tv = new TextView(this);
		tv.setTextColor(Color.WHITE);
		tv.setText("");
		LinearLayout.LayoutParams param2 = new LinearLayout.LayoutParams(FP, WC);
		param2.topMargin = 10;
		layout.addView(tv, param2);
		setContentView(layout);
		// ------------------------
	}

	public void onClick(View v) {
		switch (v.getId()) {
		case 101:
			progressDialog = ProgressDialog.show(this,
	    			 "please wait…","Loading",true);
	 		th1 = new myThread();
	 		th1.start();
	 		setTitle("mainThread....");
			break;
		case 102:
			finish();
			break;
		}
	}
	class myThread extends Thread {
        @Override
        public void run() {
        	 try{
        		  sleep(3000); //故意延遲
                }
            catch(Exception e)
                {
              	  e.printStackTrace(); 
                }
            // 为什么这里可以控制Dialog的可见性????????????
            //子线程来执行
            progressDialog.dismiss();
          }
   }
}
/*
上述程式又可寫為：
public class ac01 extends Activity 
    implements OnClickListener, Runnable{
	     //………………(省略)
       	public void onClick(View v) {
		switch(v.getId()){
		case 101:
			progressDialog = ProgressDialog.show(this,
	    			 "please wait…","Loading",true);
	 		th1 = new Thread(this);
	 		th1.start();
	 		setTitle("mainThread....");
            break;
		case 102:
	    	finish();
			break;
		}
	}
    public void run() {
         	 try{
         		  Thread.sleep(6000); //故意延遲
                 }
             catch(Exception e)
                 {
               	  e.printStackTrace(); 
                 }
             progressDialog.dismiss();
           }
    }
*/