BackupDataInput

Class Overview

Provides the structured interface through which a BackupAgent reads information from the backup data set, via its onRestore() method. The data is presented as a set of "entities," each representing one named record as previously stored by the agent's onBackup() implementation. An entity is composed of a descriptive header plus a byte array that holds the raw data saved in the remote backup.

The agent must consume every entity in the data stream, otherwise the restored state of the application will be incomplete.

Example

A typical onRestore() implementation might be structured something like this:

 public void onRestore(BackupDataInput data, int appVersionCode,
                       ParcelFileDescriptor newState) {
     while (data.readNextHeader()) {
         String key = data.getKey();
         int dataSize = data.getDataSize();

         if (key.equals(MY_BACKUP_KEY_ONE)) {
             // process this kind of record here
             byte[] buffer = new byte[dataSize];
             data.readEntityData(buffer, 0, dataSize); // reads the entire entity at once

             // now 'buffer' holds the raw data and can be processed however
             // the agent wishes
             processBackupKeyOne(buffer);
         } else if (key.equals(MY_BACKUP_KEY_TO_IGNORE) {
             // a key we recognize but wish to discard
             data.skipEntityData();
         } // ... etc.
    }
 }

Summary

[Expand] Inherited Methods

From class java.lang.Object Object clone() Creates and returns a copy of this Object. boolean equals(Object o) Compares this instance with the specified object and indicates if they are equal. void finalize() Invoked when the garbage collector has detected that this instance is no longer reachable. final Class<?> getClass() Returns the unique instance of Class that represents this object's class. int hashCode() Returns an integer hash code for this object. final void notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. final void notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up. String toString() Returns a string containing a concise, human-readable description of this object. final void wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object. final void wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires. final void wait(long millis) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.