Android應用開發之版本更新你莫愁

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        今天我們學習如何實現Android應用的自動更新版本功能，這是在各種語言編寫的應用中都會經常遇到的情景。當我們的應用檢測到網絡上有新版本發佈時，系統會提示是否下載新版本應用，當新版本應用下載完畢後，系統會自動安裝下載的新版本應用（或跳轉到相關安裝頁面詢問）。我們將下載的應用存放在sdcard中，由於整個流程涉及對sdcard的讀寫操作，所以要賦給我們應用讀寫外存的權限。下面給出該場景的案例：

1案例技術要點

1.1程序清單文件中需要配置如下權限：

訪問網絡

<uses-permission android:name="android.permission.INTERNET"/>

讀取sdcard

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

寫入sdcard

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

1.2創建一個HttpURLConnection連接，從網絡下載新版本應用到本地

1.3創建一個ProgressBar下載進度條，實時顯示下載應用的進度

1.4應用下載完畢後，構建Intent跳轉至其安裝頁面，該Intent的配置如下：

Action：Intent.ACTION_VIEW

DataAndType：Uri.parse("file://" + appFile.toString())，"application/vnd.android.package-archive"

2案例代碼陳列

2.1AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="cn.lynn.autoupdate"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".AutoUpdateMainActivity"
            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>

2.2strings.xml

<resources>
    <string name="app_name">Android實現應用自動更新</string>
</resources>

2.3main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

2.4下載進度條佈局文件：progressBar.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ProgressBar 
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

2.5AutoUpdateMainActivity.java

package cn.lynn.autoupdate;

import android.app.Activity;
import android.os.Bundle;

public class AutoUpdateMainActivity extends Activity {
    private UpdateAppManager updateManager;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        updateManager = new UpdateAppManager(this);
        updateManager.checkUpdateInfo();
    }

}

2.6UpdateAppManager.java

package cn.lynn.autoupdate;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ProgressBar;

public class UpdateAppManager {
    // 文件分隔符
    private static final String FILE_SEPARATOR = "/";
    // 外存sdcard存放路徑
    private static final String FILE_PATH = Environment.getExternalStorageDirectory() + FILE_SEPARATOR +"autoupdate" + FILE_SEPARATOR;
    // 下載應用存放全路徑
    private static final String FILE_NAME = FILE_PATH + "autoupdate.apk";
    // 更新應用版本標記
    private static final int UPDARE_TOKEN = 0x29;
    // 準備安裝新版本應用標記
    private static final int INSTALL_TOKEN = 0x31;
    
    private Context context;
    private String message = "檢測到本程序有新版本發佈，建議您更新！";
    // 以華爲天天聊hotalk.apk爲例
    private String spec = "http://222.42.1.209:81/1Q2W3E4R5T6Y7U8I9O0P1Z2X3C4V5B/mt.hotalk.com:8080/release/hotalk1.9.17.0088.apk";
    // 下載應用的對話框
    private Dialog dialog;
    // 下載應用的進度條
    private ProgressBar progressBar;
    // 進度條的當前刻度值
    private int curProgress;
    // 用戶是否取消下載
    private boolean isCancel;
    
    public UpdateAppManager(Context context) {
        this.context = context;
    }
    
    private final Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case UPDARE_TOKEN:
                progressBar.setProgress(curProgress);
                break;

            case INSTALL_TOKEN:
                installApp();
                break;
            }
        }
    };
    
    /**
     * 檢測應用更新信息
     */
    public void checkUpdateInfo() {
        showNoticeDialog();
    }

    /**
     * 顯示提示更新對話框
     */
    private void showNoticeDialog() {
        new AlertDialog.Builder(context)
            .setTitle("軟件版本更新")
            .setMessage(message)
            .setPositiveButton("下載", new OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                    showDownloadDialog();
                }
            }).setNegativeButton("以後再說", new OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            }).create().show();
    }

    /**
     * 顯示下載進度對話框
     */
    private void showDownloadDialog() {
        View view = LayoutInflater.from(context).inflate(R.layout.progressbar, null);
        progressBar = (ProgressBar) view.findViewById(R.id.progressBar);
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setTitle("軟件版本更新");
        builder.setView(view);
        builder.setNegativeButton("取消", new OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                    isCancel = true;
                }
            });
        dialog = builder.create();
        dialog.show();
        downloadApp();
    }

    /**
     * 下載新版本應用
     */
    private void downloadApp() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                URL url = null;
                InputStream in = null;
                FileOutputStream out = null;
                HttpURLConnection conn = null;
                try {
                    url = new URL(spec);
                    conn = (HttpURLConnection) url.openConnection();
                    conn.connect();
                    long fileLength = conn.getContentLength();
                    in = conn.getInputStream();
                    File filePath = new File(FILE_PATH);
                    if(!filePath.exists()) {
                        filePath.mkdir();
                    }
                    out = new FileOutputStream(new File(FILE_NAME));
                    byte[] buffer = new byte[1024];
                    int len = 0;
                    long readedLength = 0l;
                    while((len = in.read(buffer)) != -1) {
                        // 用戶點擊“取消”按鈕，下載中斷
                        if(isCancel) {
                            break;
                        }
                        out.write(buffer, 0, len);
                        readedLength += len;
                        curProgress = (int) (((float) readedLength / fileLength) * 100);
                        handler.sendEmptyMessage(UPDARE_TOKEN);
                        if(readedLength >= fileLength) {
                            dialog.dismiss();
                            // 下載完畢，通知安裝
                            handler.sendEmptyMessage(INSTALL_TOKEN);
                            break;
                        }
                    }
                    out.flush();
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if(out != null) {
                        try {
                            out.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if(in != null) {
                        try {
                            in.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if(conn != null) {
                        conn.disconnect();
                    }
                }
            }
        }).start();
    }
    
    /**
     * 安裝新版本應用
     */
    private void installApp() {
        File appFile = new File(FILE_NAME);
        if(!appFile.exists()) {
            return;
        }
        // 跳轉到新版本應用安裝頁面
        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(Uri.parse("file://" + appFile.toString()), "application/vnd.android.package-archive");
        context.startActivity(intent);
    }
}

3案例效果展示

  

        新版本應用下載後，sdcard相關存放目錄如下：