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在應用中, 為了提高用戶體驗, 會提供更新版本的功能. 那麼如何實現呢? 我寫了一個簡單的Demo, 說明一下, 需要注意幾個細節. 使用了Retrofit和Rx處理網絡請求.

Github下載地址

1. 邏輯

訪問服務器, 根據是否包含新版本, 判斷是否需要更新.
下載Apk, 下載完成後, 自動安裝, 高版本會覆蓋低版本.

邏輯:

public class MainActivity extends AppCompatActivity {

    private static final String APP_NAME = 'Ped_android';
    private static final String VERSION = '1.0.0';
    private static final String INFO_NAME = '計步器';
    private static final String STORE_APK = 'chunyu_apk';

    @Bind(R.id.main_b_install_apk) Button mBInstallApk;

    private UpdateAppUtils.UpdateCallback mUpdateCallback; // 更新回調

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);

        mUpdateCallback = new UpdateAppUtils.UpdateCallback() {
            @Override public void onSuccess(UpdateInfo updateInfo) {
                Toast.makeText(MainActivity.this, '有更新', Toast.LENGTH_SHORT).show();
                UpdateAppUtils.downloadApk(MainActivity.this, updateInfo, INFO_NAME, STORE_APK);
            }

            @Override public void onError() {
                Toast.makeText(MainActivity.this, '無更新', Toast.LENGTH_SHORT).show();
            }
        };

        mBInstallApk.setOnClickListener(new View.OnClickListener() {
            @Override public void onClick(View v) {
                UpdateAppUtils.checkUpdate(APP_NAME, VERSION, mUpdateCallback);
            }
        });
    }
}

UpdateAppUtils是核心下載類. 輸入App的代號, 版本號, 異步回調, 發送到服務器, 判斷是否需要更新. 如果存在新版本, 則下載Apk, 並自動安裝更新.

2. 網絡請求

更新請求, 參數是App代號和當前版本號.

/**
 * 更新服務
 * <p>
 * Created by wangchenlong on 16/1/4.
 */
public interface UpdateService {
    String ENDPOINT = 'http://www.chunyuyisheng.com';

    // 獲取個人信息
    @GET('/cmsapi/app/update')
    Observable<UpdateInfo> getUpdateInfo(
            @Query('appName') String appName,
            @Query('version') String version);
}

創建服務的工廠類.

/**
 * 創建Retrofit服務
 * <p>
 * Created by wangchenlong on 16/1/4.
 */
public class ServiceFactory {
    public static <T> T createServiceFrom(final Class<T> serviceClass, String endpoint) {
        Retrofit adapter = new Retrofit.Builder()
                .baseUrl(endpoint)
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) // 添加Rx適配器
                .addConverterFactory(GsonConverterFactory.create()) // 添加Gson轉換器
                .build();
        return adapter.create(serviceClass);
    }
}

更新信息的Json類.

/**
 * 更新信息(JSON)
 * <p>
 * Created by wangchenlong on 16/1/4.
 */
public class UpdateInfo {
    public Data data; // 信息
    public Integer error_code; // 錯誤代碼
    public String error_msg; // 錯誤信息

    public static class Data {
        public String curVersion; // 當前版本
        public String appURL; // 下載地址
        public String description; // 描述
        public String minVersion; // 最低版本
        public String appName; // 應用名稱
    }

    @Override public String toString() {
        return '當前版本: ' + data.curVersion + ', 下載地址: ' + data.appURL + ', 描述信息: ' + data.description
                + ', 最低版本: ' + data.minVersion + ', 應用代稱: ' + data.appName
                + ', 錯誤代碼: ' + error_code + ', 錯誤信息: ' + error_msg;
    }
}

3. 請求和下載

更新庫的主類, 包含檢查更新(checkUpdate)和下載Apk(downloadApk)兩個重要方法.

/**
 * 更新管理器
 * <p>
 * Created by wangchenlong on 16/1/6.
 */
@SuppressWarnings('unused')
public class UpdateAppUtils {

    @SuppressWarnings('unused')
    private static final String TAG = 'DEBUG-WCL: ' + UpdateAppUtils.class.getSimpleName();

    /**
     * 檢查更新
     */
    @SuppressWarnings('unused')
    public static void checkUpdate(String appCode, String curVersion, UpdateCallback updateCallback) {
        UpdateService updateService =
                ServiceFactory.createServiceFrom(UpdateService.class, UpdateService.ENDPOINT);

        updateService.getUpdateInfo(appCode, curVersion)
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(updateInfo -> onNext(updateInfo, updateCallback),
                        throwable -> onError(throwable, updateCallback));
    }

    // 顯示信息
    private static void onNext(UpdateInfo updateInfo, UpdateCallback updateCallback) {
        Log.e(TAG, '返回數據: ' + updateInfo.toString());
        if (updateInfo.error_code != 0 || updateInfo.data == null ||
                updateInfo.data.appURL == null) {
            updateCallback.onError(); // 失敗
        } else {
            updateCallback.onSuccess(updateInfo);
        }
    }

    // 錯誤信息
    private static void onError(Throwable throwable, UpdateCallback updateCallback) {
        updateCallback.onError();
    }

    /**
     * 下載Apk, 並設置Apk地址,
     * 默認位置: /storage/sdcard0/Download
     *
     * @param context    上下文
     * @param updateInfo 更新信息
     * @param infoName   通知名稱
     * @param storeApk   存儲的Apk
     */
    @SuppressWarnings('unused')
    public static void downloadApk(
            Context context, UpdateInfo updateInfo,
            String infoName, String storeApk
    ) {
        if (!isDownloadManagerAvailable()) {
            return;
        }

        String description = updateInfo.data.description;
        String appUrl = updateInfo.data.appURL;

        if (appUrl == null || appUrl.isEmpty()) {
            Log.e(TAG, '請填寫'App下載地址'');
            return;
        }

        appUrl = appUrl.trim(); // 去掉首尾空格

        if (!appUrl.startsWith('http')) {
            appUrl = 'http://' + appUrl; // 添加Http信息
        }

        Log.e(TAG, 'appUrl: ' + appUrl);

        DownloadManager.Request request;
        try {
            request = new DownloadManager.Request(Uri.parse(appUrl));
        } catch (Exception e) {
            e.printStackTrace();
            return;
        }
        request.setTitle(infoName);
        request.setDescription(description);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        }
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, storeApk);

        Context appContext = context.getApplicationContext();
        DownloadManager manager = (DownloadManager)
                appContext.getSystemService(Context.DOWNLOAD_SERVICE);

        // 存儲下載Key
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(appContext);
        sp.edit().putLong(PrefsConsts.DOWNLOAD_APK_ID_PREFS, manager.enqueue(request)).apply();
    }

    // 最小版本號大於9
    private static boolean isDownloadManagerAvailable() {
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD;
    }

    // 錯誤回調
    public interface UpdateCallback {
        void onSuccess(UpdateInfo updateInfo);

        void onError();
    }
}

檢查更新: 創建服務, 在新線程中發送請求, 在主線程中接收數據, 判斷成功和失敗.

    /**
     * 檢查更新
     */
    @SuppressWarnings('unused')
    public static void checkUpdate(String appCode, String curVersion, UpdateCallback updateCallback) {
        UpdateService updateService =
                ServiceFactory.createServiceFrom(UpdateService.class, UpdateService.ENDPOINT);

        updateService.getUpdateInfo(appCode, curVersion)
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(updateInfo -> onNext(updateInfo, updateCallback),
                        throwable -> onError(throwable, updateCallback));
    }

下載Apk: 轉換和解析Url, 設置通知信息和存儲位置, 存儲下載Id, 自動安裝更新.

    /**
     * 下載Apk, 並設置Apk地址,
     * 默認位置: /storage/sdcard0/Download
     *
     * @param context    上下文
     * @param updateInfo 更新信息
     * @param infoName   通知名稱
     * @param storeApk   存儲的Apk
     */
    @SuppressWarnings('unused')
    public static void downloadApk(
            Context context, UpdateInfo updateInfo,
            String infoName, String storeApk
    ) {
        if (!isDownloadManagerAvailable()) {
            return;
        }

        String description = updateInfo.data.description;
        String appUrl = updateInfo.data.appURL;

        if (appUrl == null || appUrl.isEmpty()) {
            Log.e(TAG, '請填寫'App下載地址'');
            return;
        }

        appUrl = appUrl.trim(); // 去掉首尾空格

        if (!appUrl.startsWith('http')) {
            appUrl = 'http://' + appUrl; // 添加Http信息
        }

        Log.e(TAG, 'appUrl: ' + appUrl);

        DownloadManager.Request request;
        try {
            request = new DownloadManager.Request(Uri.parse(appUrl));
        } catch (Exception e) {
            e.printStackTrace();
            return;
        }
        request.setTitle(infoName);
        request.setDescription(description);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        }
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, storeApk);

        Context appContext = context.getApplicationContext();
        DownloadManager manager = (DownloadManager)
                appContext.getSystemService(Context.DOWNLOAD_SERVICE);

        // 存儲下載Key
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(appContext);
        sp.edit().putLong(PrefsConsts.DOWNLOAD_APK_ID_PREFS, manager.enqueue(request)).apply();
    }

使用DownloadManager下載文件是Android的推薦方式.
存儲下載Id(manager.enqueue(request))是為了在安裝應用時, 找到Apk.
默認存儲地址/storage/sdcard0/Download.

4.自動安裝

注冊廣播接收器, 接收消息ACTION_DOWNLOAD_COMPLETE, 下載完成會發送廣播. 獲取下載文件的Uri, 進行匹配, 發送安裝消息, 自動安裝.

/**
 * 安裝下載接收器
 * <p>
 * Created by wangchenlong on 16/1/5.
 */
public class InstallReceiver extends BroadcastReceiver {

    private static final String TAG =
            'DEBUG-WCL: ' + InstallReceiver.class.getSimpleName();

    // 安裝下載接收器
    @Override public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {
            long downloadApkId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
            installApk(context, downloadApkId);
        }
    }

    // 安裝Apk
    private void installApk(Context context, long downloadApkId) {
        // 獲取存儲ID
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context);
        long id = sp.getLong(PrefsConsts.DOWNLOAD_APK_ID_PREFS, -1L);

        if (downloadApkId == id) {
            DownloadManager dManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
            Intent install = new Intent(Intent.ACTION_VIEW);
            Uri downloadFileUri = dManager.getUriForDownloadedFile(downloadApkId);
            if (downloadFileUri != null) {
                install.setDataAndType(downloadFileUri, 'application/vnd.android.package-archive');
                install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(install);
            } else {
                Log.e(TAG, '下載失敗');
            }
        }
    }
}

安裝本應用下載的Apk, 不安裝其他Apk, 存儲下載Id, 與廣播Id進行匹配.
下載失敗, 也會發送下載完成(ACTION_DOWNLOAD_COMPLETE)廣播, Uri可能為空, 需要判斷, 否則發生崩潰.

OK, that’s all! Enjoy It!