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/*
 * Copyright OmniFaces
 *
 * Licensed 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
 *
 *     https://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.omnifaces.io;

import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.Writer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;

/**
 * This resettable buffered writer will buffer everything until the given buffer size, regardless of flush calls.
 * Only when the buffer size is exceeded, or when close is called, then the buffer will be actually flushed.
 * 

* There is a {@link #reset()} method which enables the developer to reset the buffer, as long as it's not flushed yet, * which can be determined by {@link #isResettable()}. * * @author Bauke Scholtz * @see ResettableBufferedOutputStream */ public class ResettableBufferedWriter extends Writer implements ResettableBuffer { // Variables ------------------------------------------------------------------------------------------------------ private Writer writer; private Charset charset; private CharArrayWriter buffer; private int bufferSize; private int writtenBytes; // Constructors --------------------------------------------------------------------------------------------------- /** * Construct a new resettable buffered writer which wraps the given writer and forcibly buffers everything until * the given buffer size in bytes, regardless of flush calls. The given character encoding is used to measure the * amount of already written bytes in the buffer. * regardless of flush calls. * @param writer The wrapped writer. * @param bufferSize The buffer size. * @param characterEncoding The character encoding. */ public ResettableBufferedWriter(Writer writer, int bufferSize, String characterEncoding) { this.writer = writer; this.bufferSize = bufferSize; charset = Charset.forName(characterEncoding); buffer = new CharArrayWriter(bufferSize); } // Actions -------------------------------------------------------------------------------------------------------- @Override public void write(char[] chars, int offset, int length) throws IOException { if (buffer != null) { writtenBytes += charset.encode(CharBuffer.wrap(chars, offset, length)).limit(); if (writtenBytes > bufferSize) { writer.write(buffer.toCharArray()); writer.write(chars, offset, length); buffer = null; } else { buffer.write(chars, offset, length); } } else { writer.write(chars, offset, length); } } @Override public void reset() { buffer = new CharArrayWriter(bufferSize); writtenBytes = 0; } @Override public void flush() throws IOException { if (buffer == null) { writer.flush(); } } @Override public void close() throws IOException { if (buffer != null) { writer.write(buffer.toCharArray()); buffer = null; } writer.close(); } @Override public boolean isResettable() { return buffer != null; } }





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