Data backup

Data Backup

Kewang

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Backup data to the cloud

Restore data when reinstalled app

Requires API Level 8+

What is Backup Service ?

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Getting Started

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Getting Started

Register service & declare agent

Extend backup agent

BackupAgent

BackupAgentHelper

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Register service & declare agent

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Register service & declare agent<manifest>

<application android:backupAgent="ExampleAgent" > <meta-data android:name="com.google.android.backup.api_key" android:value="AEdPqrEAAAAIW4p30C1GTNjzBOqWrb0clI7_OCWxm3ddIgkKhw" />

</application>

</manifest> backupAgentbackup.api_key

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Extend backup agent

BackupAgent

Version data format

Back up the portions of data

Back up data in a database

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Extend BackupAgent

public class ExampleAgent extends BackupAgent { @Override public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState) { // TODO }

@Override public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState) { // TODO }}

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Extend BackupAgent

onBackupParcelFileDescriptor oldState

read-only last backup state, may be nullcontains representation of the datafrom the last onBackup's newState

BackupDataOutput datause to deliver backup data

ParcelFileDescriptor newStaterecord the final backup state after writing data

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Extend BackupAgent

onRestoreBackupDataInput data

can read backup data

int appVersionCodeManifest attribute when data was backed upcan cross-check app version

ParcelFileDescriptor newStatewrite the state of data

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Implement onBackup (1/2)boolean doBackup = (oldState == null);

synchronized (BackupRestoreActivity.sDataLock) { RandomAccessFile f = new RandomAccessFile(mFile, "r");

mFilling = f.readInt(); mAddMayo = f.readBoolean(); mAddTomato = f.readBoolean();

f.close();}

if (!doBackup) { doBackup = compareStateFile(oldState);}

read local fileis newest

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if (doBackup) { ByteArrayOutputStream buf = new ByteArrayOutputStream(); DataOutputStream out = new DataOutputStream(buf);

out.writeInt(mFilling); out.writeBoolean(mAddMayo); out.writeBoolean(mAddTomato);

byte[] buffer = buf.toByteArray(); int len = buffer.length;

data.writeEntityHeader(APP_DATA_KEY, len); data.writeEntityData(buffer, len);}

writeStateFile(newState);

Implement onBackup (2/2)

back up

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Implement onRestore (1/3)

String key = data.getKey();int size = data.getDataSize();

if (!APP_DATA_KEY.equals(key)) { data.skipEntityData();}

data is invalid, skip it

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Implement onRestore (2/3)

if (APP_DATA_KEY.equals(key)) { byte[] buf = new byte[size];

data.readEntityData(buf, 0, size);

ByteArrayInputStream is = new ByteArrayInputStream(buf); DataInputStream in = new DataInputStream(is);

mFilling = in.readInt(); mAddMayo = in.readBoolean(); mAddTomato = in.readBoolean();

data is valid, read it

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Implement onRestore (3/3)

synchronized (BackupRestoreActivity.sDataLock) { RandomAccessFile f = new RandomAccessFile(mFile, "rw");

f.setLength(0L); f.writeInt(mFilling); f.writeBoolean(mAddMayo); f.writeBoolean(mAddTomato);

f.close(); }}

writeStateFile(newState);

write data to local file

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Another backup agent

BackupAgentHelper

Back up SharedPreferences

Back up a file

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Extend BackupAgentHelper

public class ExampleAgent extends BackupAgentHelper { @Override public void onCreate() { FileBackupHelper helper = new FileBackupHelper(this, "file");

addHelper("key", helper); }}

can also use SharedPreferencesBackupHelper

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How to using & testing it ?

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How to using & testing it ?

mBackupManager.dataChanged();

Request backup

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How to using & testing it ?

mBackupManager.requestRestore(new RestoreObserver() { @Override public void restoreStarting(int numPackages) { }

@Override public void onUpdate(int nowBeingRestored,String currentPackage) { }

@Override public void restoreFinished(int error) { }});

Request restore

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How to using & testing it ?

adb shell bmgr run

adb shell bmgr backup <package>

adb shell bmgr restore <package>

adb shell bmgr wipe <package>

adb shell bmgr enable <boolean>

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FAQ

Storage size ?

unknown

Backup data TTL ?

unknown

Can synchronizing ?

CANNOT

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References

Android Backup Service

Data Backup

Using the Backup API

Sample Project->BackupRestore

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