转载 Android progressDilog简单示例

面来介绍主要的Activity
ProgressBarDemo.java

package com.lveyo.android.demo.progressbar;

import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class ProgressBarDemo extends Activity {

    private TextView statusTextView;
    private Button beginBtn;
    private ProgressDialog progressDialog;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        statusTextView = (TextView)findViewById(R.id.status);
        beginBtn = (Button)findViewById(R.id.beginBtn);
        setListener();
    }

    /**
     * 用Handler来更新UI
     */
    private Handler handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {

            //关闭ProgressDialog
            progressDialog.dismiss();

            //更新UI
            statusTextView.setText("Completed!");
        }};


    /**
     * 点击按钮事件listener
     */
    private void setListener(){
        beginBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                //显示ProgressDialog
                progressDialog = ProgressDialog.show(ProgressBarDemo.this, "Loading...", "Please wait...", true, false);

                //新建线程
                new Thread(){

                    @Override
                    public void run() {
                        //需要花时间计算的方法
                        Calculation.calculate(4);

                        //向handler发消息
                        handler.sendEmptyMessage(0);
                    }}.start();
            }
        });
    }

}

Calculation.java

package com.lveyo.android.demo.progressbar;

/**
 * 示意方法
 * @author lveyo
 *
 */
public class Calculation {

    public static void calculate(int sleepSeconds){
        try {
            Thread.sleep(sleepSeconds * 1000);
        } catch (Exception e) {
            // TODO: handle exception
        }
    }

}

main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView android:id="@+id/status"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
<Button android:id="@+id/beginBtn"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="begin"
    />
</LinearLayout>

在android中，通常我们无法在单独的线程中更新UI，而要在主线程中，这也就是为什么我们要使用 Handler了，当handler收到消息中，它会把它放入到队列中等待执行，通常来说这会很快被执行。