se.softhouse.common.testlib.Streams.java Source code

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Here is the source code for se.softhouse.common.testlib.Streams.java

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/* Copyright 2013 Jonatan Jnsson
 *
 *    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
 *
 *        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 se.softhouse.common.testlib;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;

import javax.annotation.concurrent.Immutable;

import com.google.common.base.Charsets;
import com.google.common.io.CharStreams;
import com.google.common.util.concurrent.ListenableFuture;

/**
 * Utility for working with {@link Readable} and {@link InputStream stream} instances.
 */
@Immutable
public final class Streams {
    private Streams() {
    }

    /**
     * Reads from {@code source} asynchronously. Use {@link Future#get()} to get the
     * characters read. Characters will be read using {@link Charsets#UTF_8 UTF-8}. A typical use
     * case is to avoid <a
     * href="http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=4">deadlock
     * pitfalls</a> when launching {@link Process processes}.
     */
    public static ListenableFuture<String> readAsynchronously(InputStream source) {
        final Readable sourceInUTF8 = new InputStreamReader(source, Charsets.UTF_8);
        Callable<String> reader = new Callable<String>() {
            @Override
            public String call() throws Exception {
                StringBuilder result = new StringBuilder();
                CharStreams.copy(sourceInUTF8, result);
                return result.toString();
            }
        };
        return Concurrently.run(reader);
    }
}