Android 简明教程

Android - Progress Circle

构建进度条的最简单方法是使用名为 ProgressDialog 的类。加载栏也可以通过该类生成。条形图和圆形之间的唯一逻辑差异在于，前者用于在知道等待特定任务的总时间时使用，而后者用于在不知道等待时间时使用。

The easiest way to make a progress circle is using through a class called ProgressDialog. The loading bar can also be made through that class. The only logical difference between bar and circle is , that the former is used when you know the total time for waiting for a particular task whereas the later is used when you don’t know the waiting time.

为此，您需要实例化此类的对象。它的语法为。

In order to this , you need to instantiate an object of this class. Its syntax is.

ProgressDialog progress = new ProgressDialog(this);

现在您可以设置此对话框的一些属性。如其样式和文本等。

Now you can set some properties of this dialog. Such as, its style,its text e.t.c

progress.setMessage("Downloading Music :) ");
progress.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progress.setIndeterminate(true);

除了这些方法外，ProgressDialog 类还提供了其他方法。

Apart from these methods, there are other methods that are provided by the ProgressDialog class.

Sr.No	Classes & Description
1	getMax() This methods returns the maximum value of the progress
2	incrementProgressBy(int diff) This method increment the progress bar by the difference of value passed as a parameter
3	setIndeterminate(boolean indeterminate) This method set the progress indicator as determinate or indeterminate
4	setMax(int max) This method set the maximum value of the progress dialog
5	setProgress(int value) This method is used to update the progress dialog with some specific value
6	show(Context context, CharSequence title, CharSequence message) This is a static method, used to display progress dialog

Example

此示例演示了进度对话框的旋转使用。它显示在按下按钮时旋转进度对话框。

This example demonstrates the spinning use of the progress dialog. It display a spinning progress dialog on pressing the button.

要对此示例进行实验，您需要在以下步骤开发应用程序后在实际设备上运行它。

To experiment with this example, you need to run this on an actual device on after developing the application according to the steps below.

Steps	Description
1	You will use Android Studio to create an Android application under a package com.example.sairamkrishna.myapplication.
2	Modify src/MainActivity.java file to add progress code to display the spinning progress dialog.
3	Modify res/layout/activity_main.xml file to add respective XML code.
4	Run the application and choose a running android device and install the application on it and verify the results.

以下是修改后的主活动文件 src/MainActivity.java. 的内容

Following is the content of the modified main activity file src/MainActivity.java.

package com.example.sairamkrishna.myapplication;

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

public class MainActivity extends Activity {
   Button b1;
   private  ProgressDialog progressBar;
   private int progressBarStatus = 0;
   private Handler progressBarbHandler = new Handler();
   private long fileSize = 0;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      b1=(Button)findViewById(R.id.button);

      b1.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            progressBar = new ProgressDialog(v.getContext());
            progressBar.setCancelable(true);
            progressBar.setMessage("File downloading ...");
            progressBar.setProgressStyle(ProgressDialog.STYLE_SPINNER);
            progressBar.setProgress(0);
            progressBar.setMax(100);
            progressBar.show();
            progressBarStatus = 0;

            fileSize = 0;
            new Thread(new Runnable() {
               public void run() {
                  while (progressBarStatus < 100) {
                     progressBarStatus = downloadFile();

                     try {
                        Thread.sleep(1000);
                     } catch (InterruptedException e) {
                        e.printStackTrace();
                     }

                     progressBarbHandler.post(new Runnable() {
                        public void run() {
                           progressBar.setProgress(progressBarStatus);
                        }
                     });
                  }

                  if (progressBarStatus >= 100) {
                     try {
                        Thread.sleep(2000);
                     } catch (InterruptedException e) {
                        e.printStackTrace();
                     }
                     progressBar.dismiss();
                  }
               }
            }).start();
         }
      });
   }

   public int downloadFile() {
      while (fileSize <= 1000000) {
         fileSize++;

         if (fileSize == 100000) {
            return 10;
         }else if (fileSize == 200000) {
            return 20;
         }else if (fileSize == 300000) {
            return 30;
         }else if (fileSize == 400000) {
            return 40;
         }else if (fileSize == 500000) {
            return 50;
         }else if (fileSize == 700000) {
            return 70;
         }else if (fileSize == 800000) {
            return 80;
         }
      }
      return 100;
   }
}

将 res/layout/activity_main.xml 的内容修改为以下内容

Modify the content of res/layout/activity_main.xml to the following

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

   <TextView android:text="Music Palyer" android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/textview"
      android:textSize="35dp"
      android:layout_alignParentTop="true"
      android:layout_centerHorizontal="true" />

   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Tutorials point"
      android:id="@+id/textView"
      android:layout_below="@+id/textview"
      android:layout_centerHorizontal="true"
      android:textColor="#ff7aff24"
      android:textSize="35dp" />

   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="download"
      android:id="@+id/button"
      android:layout_alignParentBottom="true"
      android:layout_centerHorizontal="true"
      android:layout_marginBottom="112dp" />

   <ImageView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/imageView"
      android:src="@drawable/abc"
      android:layout_below="@+id/textView"
      android:layout_centerHorizontal="true" />

</RelativeLayout>

将 res/values/string.xml 修改为以下内容

Modify the res/values/string.xml to the following

<resources>
   <string name="app_name">My Application</string>
</resources>

这是默认 AndroidManifest.xml

This is the default AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.sairamkrishna.myapplication" >

   <application
      android:allowBackup="true"
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/AppTheme" >

      <activity
         android:name="com.example.sairamkrishna.myapplication.MainActivity"
         android:label="@string/app_name" >

         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>

   </application>
</manifest>

让我们尝试运行您的应用程序。要从 Android Studio 运行应用，请打开项目的一个活动文件，然后单击工具栏中的“运行”图标。在启动应用程序之前，Android Studio 将显示以下窗口，供您选择要在哪儿运行 Android 应用程序。

Let’s try to run your application. To run the app from android studio, open one of your project’s activity files and click Run icon from the toolbar. Before starting your application, Android studio will display following window to select an option where you want to run your Android application.

要启动进度对话框，只需按下按钮即可。按过后，将出现以下屏幕。

Just press the button to start the Progress Dialog. After pressing , following screen would appear.