129 lines
3.1 KiB
Java
129 lines
3.1 KiB
Java
/*
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* Copyright (C) 2006 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.io;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.io.Closeable;
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import java.io.Flushable;
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import java.io.IOException;
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import java.io.Writer;
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import javax.annotation.Nullable;
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/**
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* Writer that places all output on an {@link Appendable} target. If the target
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* is {@link Flushable} or {@link Closeable}, flush()es and close()s will also
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* be delegated to the target.
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*
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* @author Alan Green
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* @author Sebastian Kanthak
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* @since 1.0
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*/
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class AppendableWriter extends Writer {
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private final Appendable target;
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private boolean closed;
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/**
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* Creates a new writer that appends everything it writes to {@code target}.
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*
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* @param target target to which to append output
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*/
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AppendableWriter(Appendable target) {
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this.target = checkNotNull(target);
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}
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/*
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* Abstract methods from Writer
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*/
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@Override
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public void write(char cbuf[], int off, int len) throws IOException {
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checkNotClosed();
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// It turns out that creating a new String is usually as fast, or faster
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// than wrapping cbuf in a light-weight CharSequence.
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target.append(new String(cbuf, off, len));
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}
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@Override
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public void flush() throws IOException {
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checkNotClosed();
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if (target instanceof Flushable) {
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((Flushable) target).flush();
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}
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}
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@Override
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public void close() throws IOException {
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this.closed = true;
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if (target instanceof Closeable) {
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((Closeable) target).close();
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}
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}
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/*
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* Override a few functions for performance reasons to avoid creating
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* unnecessary strings.
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*/
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@Override
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public void write(int c) throws IOException {
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checkNotClosed();
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target.append((char) c);
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}
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@Override
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public void write(@Nullable String str) throws IOException {
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checkNotClosed();
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target.append(str);
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}
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@Override
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public void write(@Nullable String str, int off, int len) throws IOException {
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checkNotClosed();
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// tricky: append takes start, end pair...
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target.append(str, off, off + len);
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}
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@Override
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public Writer append(char c) throws IOException {
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checkNotClosed();
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target.append(c);
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return this;
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}
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@Override
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public Writer append(@Nullable CharSequence charSeq) throws IOException {
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checkNotClosed();
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target.append(charSeq);
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return this;
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}
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@Override
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public Writer append(@Nullable CharSequence charSeq, int start, int end) throws IOException {
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checkNotClosed();
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target.append(charSeq, start, end);
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return this;
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}
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private void checkNotClosed() throws IOException {
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if (closed) {
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throw new IOException("Cannot write to a closed writer.");
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}
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}
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}
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