网上一般对进度条的示例都是如何显示,没有在任务结束如何关闭的文章,参考其他文章经过试验之后把整套进度条显示的简单示例如下:
建立android工程等工作都略去,Google一下就可以了。
下面来介绍主要的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();
- }
-
-
- private Handler handler = new Handler(){
-
- @Override
- public void handleMessage(Message msg) {
-
-
- progressDialog.dismiss();
-
-
- statusTextView.setText("Completed!");
- }};
-
-
-
- private void setListener(){
- beginBtn.setOnClickListener(new View.OnClickListener() {
-
- @Override
- public void onClick(View v) {
-
-
- progressDialog = ProgressDialog.show(ProgressBarDemo.this, "Loading...", "Please wait...", true, false);
-
-
- new Thread(){
-
- @Override
- public void run() {
-
- Calculation.calculate(4);
-
-
- handler.sendEmptyMessage(0);
- }}.start();
- }
- });
- }
-
- }
Calculation.java
- package com.lveyo.android.demo.progressbar;
-
- public class Calculation {
-
- public static void calculate(int sleepSeconds){
- try {
- Thread.sleep(sleepSeconds * 1000);
- } catch (Exception e) {
-
- }
- }
-
- }
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。