DirectOutputStream.java from DrJava at Krugle
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/*BEGIN_COPYRIGHT_BLOCK*
PLT Utilities BSD License
Copyright (c) 2007 JavaPLT group at Rice University
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Developed by: Java Programming Languages Team
Rice University
http://www.cs.rice.edu/~javaplt/
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package edu.rice.cs.plt.io;
import java.io.*;
/**
* <p>An {@code OutputStream} that supports writing directly from an {@code InputStream}. This class
* provides default implementations defined in terms of {@code InputStream} and {@code OutputStream}
* methods. Subclasses can override (at least) {@link #writeAll(InputStream, byte[])} and
* {@link #write(InputStream, int, byte[])} to provide better implementations (by, for example,
* not invoking {@link OutputStream#write(byte[])}).</p>
*
* <p>Also guarantees that, consistent with the {@link Writer} class, all write operations are
* by default defined in terms of the (declared abstract) {@link #write(byte[], int, int)} method.</p>
*
* @see DirectWriter
* @see DirectInputStream
* @see DirectReader
*/
public abstract class DirectOutputStream extends OutputStream {
protected static final int DEFAULT_BUFFER_SIZE = 1024;
/** Delegate to the more general {@link #write(byte[], int, int)} method */
@Override public void write(int b) throws IOException { write(new byte[]{ (byte) b }, 0, 1); }
/** Delegate to the more general {@link #write(byte[], int, int)} method */
@Override public void write(byte[] bbuf) throws IOException { write(bbuf, 0, bbuf.length); }
/** Subclasses are, at a minimum, required to implement this method. */
@Override public abstract void write(byte[] bbuf, int offset, int bytes) throws IOException;
/**
* Write some number of bytes, using the provided {@code InputStream} as input. Fewer bytes
* may be written if the input stream has fewer available. The default implementation
* invokes {@link #write(InputStream, int, int)} with the minimum of {@code bytes} and
* {@link #DEFAULT_BUFFER_SIZE}. Subclasses that do not rely on a buffer in
* {@link #write(InputStream, int, byte[])} should override this method.
*
* @param in A stream to be read from
* @param bytes The number of bytes to write
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written
* @throws IOException If an error occurs during reading or writing
*/
public int write(InputStream in, int bytes) throws IOException {
return write(in, bytes, (bytes < DEFAULT_BUFFER_SIZE) ? bytes : DEFAULT_BUFFER_SIZE);
}
/**
* Write some number of bytes, using the provided {@code InputStream} as input. Fewer bytes
* may be written if the input stream has fewer available. The default implementation
* invokes {@link #write(InputStream, int, byte[])} with a newly-allocated array of the given size.
* Subclasses that do not rely on a buffer in {@link #write(InputStream, int, byte[])}
* should override this method.
*
* @param in A stream to be read from
* @param bytes The number of bytes to write
* @param bufferSize The size of buffer to use (if necessary). Smaller values may reduce the amount of
* memory required; larger values may increase performance on large readers
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written
* @throws IOException If an error occurs during reading or writing
* @throws IllegalArgumentException If {@code bufferSize <= 0}
*/
public int write(InputStream in, int bytes, int bufferSize) throws IOException {
return write(in, bytes, new byte[bufferSize]);
}
/**
* Write some number of bytes, using the provided {@code InputStream} as input. Fewer bytes
* may be written if the input stream has fewer available. The given buffer is useful
* in repeated {@code write} invocations to avoid unnecessary memory allocation. The default
* implementation repeatedly fills the given buffer via a
* {@link InputStream#read(byte[], int, int)} operation, then writes it via
* {@link OutputStream#write(byte[], int, int)}. Subclasses that do not require an external buffer
* should override this method.
*
* @param in A stream to be read from
* @param bytes The number of bytes to write
* @param buffer A buffer used to copy bytes from the input stream to this stream. Note that this is only
* used to avoid unnecessary memory allocation. No assumptions are made about the buffer's
* contents (which may be overwritten), and no assumptions should be made about the contents
* of the buffer after the method invocation.
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written
* @throws IOException If an error occurs during reading or writing
* @throws IllegalArgumentException If {@code buffer} has size {@code 0}
*/
public int write(InputStream in, int bytes, byte[] buffer) throws IOException {
return IOUtil.doWriteFromInputStream(in, this, bytes, buffer);
}
/**
* Write the full contents of the given {@code InputStream} to this stream. The method will block
* until an end-of-file is reached. The default implementation invokes
* {@link #writeAll(InputStream, int)} with {@link #DEFAULT_BUFFER_SIZE}. Subclasses that know the
* size of this stream's remaining contents, or that do not rely on a buffer in
* {@link #writeAll(InputStream, byte[])}, should override this method.
*
* @param in A stream to be read from
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written (or, if the number is too large, {@code Integer.MAX_VALUE})
* @throws IOException If an error occurs during reading or writing
*/
public int writeAll(InputStream in) throws IOException {
return writeAll(in, DEFAULT_BUFFER_SIZE);
}
/**
* Write the full contents of the given {@code InputStream} to this stream. The method will block
* until an end-of-file is reached. The default implementation invokes
* {@link #writeAll(InputStream, byte[])} with a newly-allocated array of the given size. Subclasses
* that do not rely on a buffer in {@link #writeAll(InputStream, byte[])} should override this method.
*
* @param in A stream to be read from
* @param bufferSize The size of buffer to use (if necessary). Smaller values may reduce the amount of
* memory required; larger values may increase performance on large readers
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written (or, if the number is too large, {@code Integer.MAX_VALUE})
* @throws IOException If an error occurs during reading or writing
* @throws IllegalArgumentException If {@code bufferSize <= 0}
*/
public int writeAll(InputStream in, int bufferSize) throws IOException {
return writeAll(in, new byte[bufferSize]);
}
/**
* Write the full contents of the given {@code InputStream} to this stream. The given buffer is useful
* in repeated {@code writeAll} invocations to avoid unnecessary memory allocation. The method will
* block until an end-of-file is reached. The default implementation repeatedly fills the given buffer
* via a {@link InputStream#read(byte[])} operation, then writes it via {@link OutputStream#write(byte[])}.
* Subclasses that do not require an external buffer should override this method.
*
* @param in A stream to be read from
* @param buffer A buffer used to copy bytes from the input stream to this stream. Note that this is only
* used to avoid unnecessary memory allocation. No assumptions are made about the buffer's
* contents (which may be overwritten), and no assumptions should be made about the contents
* of the buffer after the method invocation.
* @return {@code -1} if the input stream is at the end of file; otherwise, the number of characters
* written (or, if the number is too large, {@code Integer.MAX_VALUE})
* @throws IOException If an error occurs during reading or writing
* @throws IllegalArgumentException If {@code buffer} has size {@code 0}
*/
public int writeAll(InputStream in, byte[] buffer) throws IOException {
return IOUtil.doCopyInputStream(in, this, buffer);
}
}
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