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Android example source code file (LocalTransport.java)

This example Android source code file (LocalTransport.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, app, application, content, debug, file, fileinputstream, fileoutputstream, illegalstateexception, io, ioexception, localtransport, os, packageinfo, restore_token, restoreset, string, tag, transport_dir_name, unable

The LocalTransport.java Android example source code

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.internal.backup;

import android.app.backup.BackupDataInput;
import android.app.backup.BackupDataOutput;
import android.app.backup.RestoreSet;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.util.Log;

import org.bouncycastle.util.encoders.Base64;

import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;

/**
 * Backup transport for stashing stuff into a known location on disk, and
 * later restoring from there.  For testing only.
 */

public class LocalTransport extends IBackupTransport.Stub {
    private static final String TAG = "LocalTransport";
    private static final boolean DEBUG = true;

    private static final String TRANSPORT_DIR_NAME
            = "com.android.internal.backup.LocalTransport";

    // The single hardcoded restore set always has the same (nonzero!) token
    private static final long RESTORE_TOKEN = 1;

    private Context mContext;
    private PackageManager mPackageManager;
    private File mDataDir = new File(Environment.getDownloadCacheDirectory(), "backup");
    private PackageInfo[] mRestorePackages = null;
    private int mRestorePackage = -1;  // Index into mRestorePackages


    public LocalTransport(Context context) {
        mContext = context;
        mPackageManager = context.getPackageManager();
    }


    public String transportDirName() {
        return TRANSPORT_DIR_NAME;
    }

    public long requestBackupTime() {
        // any time is a good time for local backup
        return 0;
    }

    public int initializeDevice() {
        if (DEBUG) Log.v(TAG, "wiping all data");
        deleteContents(mDataDir);
        return BackupConstants.TRANSPORT_OK;
    }

    public int performBackup(PackageInfo packageInfo, ParcelFileDescriptor data) {
        if (DEBUG) Log.v(TAG, "performBackup() pkg=" + packageInfo.packageName);

        File packageDir = new File(mDataDir, packageInfo.packageName);
        packageDir.mkdirs();

        // Each 'record' in the restore set is kept in its own file, named by
        // the record key.  Wind through the data file, extracting individual
        // record operations and building a set of all the updates to apply
        // in this update.
        BackupDataInput changeSet = new BackupDataInput(data.getFileDescriptor());
        try {
            int bufSize = 512;
            byte[] buf = new byte[bufSize];
            while (changeSet.readNextHeader()) {
                String key = changeSet.getKey();
                String base64Key = new String(Base64.encode(key.getBytes()));
                File entityFile = new File(packageDir, base64Key);

                int dataSize = changeSet.getDataSize();

                if (DEBUG) Log.v(TAG, "Got change set key=" + key + " size=" + dataSize
                        + " key64=" + base64Key);

                if (dataSize >= 0) {
                    if (entityFile.exists()) {
                        entityFile.delete();
                    }
                    FileOutputStream entity = new FileOutputStream(entityFile);

                    if (dataSize > bufSize) {
                        bufSize = dataSize;
                        buf = new byte[bufSize];
                    }
                    changeSet.readEntityData(buf, 0, dataSize);
                    if (DEBUG) Log.v(TAG, "  data size " + dataSize);

                    try {
                        entity.write(buf, 0, dataSize);
                    } catch (IOException e) {
                        Log.e(TAG, "Unable to update key file " + entityFile.getAbsolutePath());
                        return BackupConstants.TRANSPORT_ERROR;
                    } finally {
                        entity.close();
                    }
                } else {
                    entityFile.delete();
                }
            }
            return BackupConstants.TRANSPORT_OK;
        } catch (IOException e) {
            // oops, something went wrong.  abort the operation and return error.
            Log.v(TAG, "Exception reading backup input:", e);
            return BackupConstants.TRANSPORT_ERROR;
        }
    }

    // Deletes the contents but not the given directory
    private void deleteContents(File dirname) {
        File[] contents = dirname.listFiles();
        if (contents != null) {
            for (File f : contents) {
                if (f.isDirectory()) {
                    // delete the directory's contents then fall through
                    // and delete the directory itself.
                    deleteContents(f);
                }
                f.delete();
            }
        }
    }

    public int clearBackupData(PackageInfo packageInfo) {
        if (DEBUG) Log.v(TAG, "clearBackupData() pkg=" + packageInfo.packageName);

        File packageDir = new File(mDataDir, packageInfo.packageName);
        for (File f : packageDir.listFiles()) {
            f.delete();
        }
        packageDir.delete();
        return BackupConstants.TRANSPORT_OK;
    }

    public int finishBackup() {
        if (DEBUG) Log.v(TAG, "finishBackup()");
        return BackupConstants.TRANSPORT_OK;
    }

    // Restore handling
    public RestoreSet[] getAvailableRestoreSets() throws android.os.RemoteException {
        // one hardcoded restore set
        RestoreSet set = new RestoreSet("Local disk image", "flash", RESTORE_TOKEN);
        RestoreSet[] array = { set };
        return array;
    }

    public long getCurrentRestoreSet() {
        // The hardcoded restore set always has the same token
        return RESTORE_TOKEN;
    }

    public int startRestore(long token, PackageInfo[] packages) {
        if (DEBUG) Log.v(TAG, "start restore " + token);
        mRestorePackages = packages;
        mRestorePackage = -1;
        return BackupConstants.TRANSPORT_OK;
    }

    public String nextRestorePackage() {
        if (mRestorePackages == null) throw new IllegalStateException("startRestore not called");
        while (++mRestorePackage < mRestorePackages.length) {
            String name = mRestorePackages[mRestorePackage].packageName;
            if (new File(mDataDir, name).isDirectory()) {
                if (DEBUG) Log.v(TAG, "  nextRestorePackage() = " + name);
                return name;
            }
        }

        if (DEBUG) Log.v(TAG, "  no more packages to restore");
        return "";
    }

    public int getRestoreData(ParcelFileDescriptor outFd) {
        if (mRestorePackages == null) throw new IllegalStateException("startRestore not called");
        if (mRestorePackage < 0) throw new IllegalStateException("nextRestorePackage not called");
        File packageDir = new File(mDataDir, mRestorePackages[mRestorePackage].packageName);

        // The restore set is the concatenation of the individual record blobs,
        // each of which is a file in the package's directory
        File[] blobs = packageDir.listFiles();
        if (blobs == null) {  // nextRestorePackage() ensures the dir exists, so this is an error
            Log.e(TAG, "Error listing directory: " + packageDir);
            return BackupConstants.TRANSPORT_ERROR;
        }

        // We expect at least some data if the directory exists in the first place
        if (DEBUG) Log.v(TAG, "  getRestoreData() found " + blobs.length + " key files");
        BackupDataOutput out = new BackupDataOutput(outFd.getFileDescriptor());
        try {
            for (File f : blobs) {
                FileInputStream in = new FileInputStream(f);
                try {
                    int size = (int) f.length();
                    byte[] buf = new byte[size];
                    in.read(buf);
                    String key = new String(Base64.decode(f.getName()));
                    if (DEBUG) Log.v(TAG, "    ... key=" + key + " size=" + size);
                    out.writeEntityHeader(key, size);
                    out.writeEntityData(buf, size);
                } finally {
                    in.close();
                }
            }
            return BackupConstants.TRANSPORT_OK;
        } catch (IOException e) {
            Log.e(TAG, "Unable to read backup records", e);
            return BackupConstants.TRANSPORT_ERROR;
        }
    }

    public void finishRestore() {
        if (DEBUG) Log.v(TAG, "finishRestore()");
    }
}

Other Android examples (source code examples)

Here is a short list of links related to this Android LocalTransport.java source code file:

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