191 lines
6.4 KiB
Java
191 lines
6.4 KiB
Java
/*
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* Copyright (C) 2012 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.BufferedWriter;
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import java.io.IOException;
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import java.io.Reader;
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import java.io.Writer;
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import java.nio.charset.Charset;
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/**
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* A destination to which characters can be written, such as a text file. Unlike
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* a {@link Writer}, a {@code CharSink} is not an open, stateful stream that can
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* be written to and closed. Instead, it is an immutable <i>supplier</i> of
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* {@code Writer} instances.
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*
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* <p>
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* {@code CharSink} provides two kinds of methods:
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* <ul>
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* <li><b>Methods that return a writer:</b> These methods should return a
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* <i>new</i>, independent instance each time they are called. The caller is
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* responsible for ensuring that the returned writer is closed.
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* <li><b>Convenience methods:</b> These are implementations of common
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* operations that are typically implemented by opening a writer using one of
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* the methods in the first category, doing something and finally closing the
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* writer that was opened.
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* </ul>
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*
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* <p>
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* Any {@link ByteSink} may be viewed as a {@code CharSink} with a specific
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* {@linkplain Charset character encoding} using
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* {@link ByteSink#asCharSink(Charset)}. Characters written to the resulting
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* {@code CharSink} will written to the {@code ByteSink} as encoded bytes.
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*
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* @since 14.0
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* @author Colin Decker
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*/
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public abstract class CharSink implements OutputSupplier<Writer> {
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/**
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* Constructor for use by subclasses.
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*/
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protected CharSink() {
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}
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/**
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* Opens a new {@link Writer} for writing to this sink. This method should
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* return a new, independent writer each time it is called.
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*
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* <p>
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* The caller is responsible for ensuring that the returned writer is closed.
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*
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* @throws IOException if an I/O error occurs in the process of opening the
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* writer
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*/
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public abstract Writer openStream() throws IOException;
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/**
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* This method is a temporary method provided for easing migration from
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* suppliers to sources and sinks.
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*
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* @since 15.0
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* @deprecated This method is only provided for temporary compatibility with the
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* {@link OutputSupplier} interface and should not be called
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* directly. Use {@link #openStream} instead. This method is
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* scheduled for removal in Guava 18.0.
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*/
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@Override
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@Deprecated
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public final Writer getOutput() throws IOException {
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return openStream();
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}
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/**
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* Opens a new buffered {@link Writer} for writing to this sink. The returned
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* stream is not required to be a {@link BufferedWriter} in order to allow
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* implementations to simply delegate to {@link #openStream()} when the stream
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* returned by that method does not benefit from additional buffering. This
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* method should return a new, independent writer each time it is called.
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*
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* <p>
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* The caller is responsible for ensuring that the returned writer is closed.
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*
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* @throws IOException if an I/O error occurs in the process of opening the
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* writer
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* @since 15.0 (in 14.0 with return type {@link BufferedWriter})
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*/
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public Writer openBufferedStream() throws IOException {
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Writer writer = openStream();
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return (writer instanceof BufferedWriter) ? (BufferedWriter) writer : new BufferedWriter(writer);
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}
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/**
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* Writes the given character sequence to this sink.
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*
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* @throws IOException if an I/O error in the process of writing to this sink
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*/
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public void write(CharSequence charSequence) throws IOException {
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checkNotNull(charSequence);
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Closer closer = Closer.create();
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try {
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Writer out = closer.register(openStream());
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out.append(charSequence);
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out.flush(); // https://code.google.com/p/guava-libraries/issues/detail?id=1330
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} catch (Throwable e) {
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throw closer.rethrow(e);
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} finally {
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closer.close();
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}
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}
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/**
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* Writes the given lines of text to this sink with each line (including the
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* last) terminated with the operating system's default line separator. This
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* method is equivalent to
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* {@code writeLines(lines, System.getProperty("line.separator"))}.
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*
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* @throws IOException if an I/O error occurs in the process of writing to this
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* sink
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*/
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public void writeLines(Iterable<? extends CharSequence> lines) throws IOException {
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writeLines(lines, System.getProperty("line.separator"));
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}
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/**
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* Writes the given lines of text to this sink with each line (including the
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* last) terminated with the given line separator.
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*
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* @throws IOException if an I/O error occurs in the process of writing to this
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* sink
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*/
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public void writeLines(Iterable<? extends CharSequence> lines, String lineSeparator) throws IOException {
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checkNotNull(lines);
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checkNotNull(lineSeparator);
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Closer closer = Closer.create();
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try {
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Writer out = closer.register(openBufferedStream());
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for (CharSequence line : lines) {
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out.append(line).append(lineSeparator);
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}
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out.flush(); // https://code.google.com/p/guava-libraries/issues/detail?id=1330
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} catch (Throwable e) {
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throw closer.rethrow(e);
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} finally {
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closer.close();
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}
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}
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/**
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* Writes all the text from the given {@link Readable} (such as a
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* {@link Reader}) to this sink. Does not close {@code readable} if it is
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* {@code Closeable}.
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*
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* @throws IOException if an I/O error occurs in the process of reading from
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* {@code readable} or writing to this sink
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*/
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public long writeFrom(Readable readable) throws IOException {
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checkNotNull(readable);
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Closer closer = Closer.create();
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try {
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Writer out = closer.register(openStream());
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long written = CharStreams.copy(readable, out);
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out.flush(); // https://code.google.com/p/guava-libraries/issues/detail?id=1330
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return written;
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} catch (Throwable e) {
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throw closer.rethrow(e);
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} finally {
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closer.close();
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}
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}
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}
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