File	Doc	Category	Size	Date	Package
MemoryFile.java	API Doc	Android 1.5 API	7972	Wed May 06 22:41:56 BST 2009	android.os

MemoryFile

• java.lang.Object

Fields Summary
private static String	TAG
private int	mFD
private int	mAddress
private int	mLength
private boolean	mAllowPurging

Constructors Summary
public MemoryFile(String name, int length) MemoryFile constructor. param name optional name for the file (can be null). param length of the memory file in bytes. // true if our ashmem region is unpinned mLength = length; mFD = native_open(name, length); mAddress = native_mmap(mFD, length);

Methods Summary
public synchronized boolean	allowPurging(boolean allowPurging) Enables or disables purging of the memory file. param allowPurging true if the operating system can purge the contents of the file in low memory situations return previous value of allowPurging boolean oldValue = mAllowPurging; if (oldValue != allowPurging) { native_pin(mFD, !allowPurging); mAllowPurging = allowPurging; } return oldValue;
public void	close() Closes and releases all resources for the memory file. if (mFD > 0) { native_close(mFD); mFD = 0; }
protected void	finalize() if (mFD > 0) { Log.e(TAG, "MemoryFile.finalize() called while ashmem still open"); close(); }
public java.io.InputStream	getInputStream() Creates a new InputStream for reading from the memory file. return InputStream return new MemoryInputStream();
public java.io.OutputStream	getOutputStream() Creates a new OutputStream for writing to the memory file. return OutputStream return new MemoryOutputStream();
public boolean	isPurgingAllowed() Is memory file purging enabled? return true if the file may be purged. return mAllowPurging;
public int	length() Returns the length of the memory file. return file length. return mLength;
private native void	native_close(int fd)
private native int	native_mmap(int fd, int length)
private native int	native_open(java.lang.String name, int length)
private native void	native_pin(int fd, boolean pin)
private native int	native_read(int fd, int address, byte[] buffer, int srcOffset, int destOffset, int count, boolean isUnpinned)
private native void	native_write(int fd, int address, byte[] buffer, int srcOffset, int destOffset, int count, boolean isUnpinned)
public int	readBytes(byte[] buffer, int srcOffset, int destOffset, int count) Reads bytes from the memory file. Will throw an IOException if the file has been purged. param buffer byte array to read bytes into. param srcOffset offset into the memory file to read from. param destOffset offset into the byte array buffer to read into. param count number of bytes to read. return number of bytes read. if (destOffset < 0 || destOffset > buffer.length || count < 0 || count > buffer.length - destOffset || srcOffset < 0 || srcOffset > mLength || count > mLength - srcOffset) { throw new IndexOutOfBoundsException(); } return native_read(mFD, mAddress, buffer, srcOffset, destOffset, count, mAllowPurging);
public void	writeBytes(byte[] buffer, int srcOffset, int destOffset, int count) Write bytes to the memory file. Will throw an IOException if the file has been purged. param buffer byte array to write bytes from. param srcOffset offset into the byte array buffer to write from. param destOffset offset into the memory file to write to. param count number of bytes to write. if (srcOffset < 0 || srcOffset > buffer.length || count < 0 || count > buffer.length - srcOffset || destOffset < 0 || destOffset > mLength || count > mLength - destOffset) { throw new IndexOutOfBoundsException(); } native_write(mFD, mAddress, buffer, srcOffset, destOffset, count, mAllowPurging);