org.apache.tools.ant.util.LazyFileOutputStream Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.tools.ant.util;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Class that delays opening the output file until the first bytes
* shall be written or the method {@link #open open} has been invoked
* explicitly.
*
* @since Ant 1.6
*/
public class LazyFileOutputStream extends OutputStream {
private FileOutputStream fos;
private File file;
private boolean append;
private boolean alwaysCreate;
private boolean opened = false;
private boolean closed = false;
/**
* Creates a stream that will eventually write to the file with
* the given name and replace it.
* @param name the filename.
*/
public LazyFileOutputStream(String name) {
this(name, false);
}
/**
* Creates a stream that will eventually write to the file with
* the given name and optionally append to instead of replacing
* it.
* @param name the filename.
* @param append if true append rather than replace.
*/
public LazyFileOutputStream(String name, boolean append) {
this(new File(name), append);
}
/**
* Creates a stream that will eventually write to the file with
* the given name and replace it.
* @param f the file to create.
*/
public LazyFileOutputStream(File f) {
this(f, false);
}
/**
* Creates a stream that will eventually write to the file with
* the given name and optionally append to instead of replacing
* it.
* @param file the file to create.
* @param append if true append rather than replace.
*/
public LazyFileOutputStream(File file, boolean append) {
this(file, append, false);
}
/**
* Creates a stream that will eventually write to the file with
* the given name, optionally append to instead of replacing
* it, and optionally always create a file (even if zero length).
* @param file the file to create.
* @param append if true append rather than replace.
* @param alwaysCreate if true create the file even if nothing to write.
*/
public LazyFileOutputStream(File file, boolean append,
boolean alwaysCreate) {
this.file = file;
this.append = append;
this.alwaysCreate = alwaysCreate;
}
/**
* Explicitly open the file for writing.
*
* Returns silently if the file has already been opened.
* @throws IOException if there is an error.
*/
public void open() throws IOException {
ensureOpened();
}
/**
* Close the file.
* @throws IOException if there is an error.
*/
public synchronized void close() throws IOException {
if (alwaysCreate && !closed) {
ensureOpened();
}
if (opened) {
fos.close();
}
closed = true;
}
/**
* Delegates to the three-arg version.
* @param b the bytearray to write.
* @throws IOException if there is a problem.
*/
public void write(byte[] b) throws IOException {
write(b, 0, b.length);
}
/**
* Write part of a byte array.
* @param b the byte array.
* @param offset write from this index.
* @param len the number of bytes to write.
* @throws IOException if there is a problem.
*/
public synchronized void write(byte[] b, int offset, int len)
throws IOException {
ensureOpened();
fos.write(b, offset, len);
}
/**
* Write a byte.
* @param b the byte to write.
* @throws IOException if there is a problem.
*/
public synchronized void write(int b) throws IOException {
ensureOpened();
fos.write(b);
}
private synchronized void ensureOpened() throws IOException {
if (closed) {
throw new IOException(file + " has already been closed.");
}
if (!opened) {
fos = new FileOutputStream(file.getAbsolutePath(), append);
opened = true;
}
}
}