com.planet57.gshell.util.io.StreamSet.java Source code

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Here is the source code for com.planet57.gshell.util.io.StreamSet.java

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/*
 * Copyright (c) 2009-present the original author or authors.
 *
 * 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 com.planet57.gshell.util.io;

import com.google.common.io.Flushables;

import javax.annotation.Nonnull;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.PrintStream;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * A set of input, output and error streams.
 *
 * @since 2.0
 */
public class StreamSet {
    /**
     * Output stream type.
     */
    public enum OutputType {
        OUT, ERR
    }

    @Nonnull
    public final InputStream in;

    @Nonnull
    public final PrintStream out;

    @Nonnull
    public final PrintStream err;

    public StreamSet(final InputStream in, final PrintStream out, final PrintStream err) {
        this.in = checkNotNull(in);
        this.out = checkNotNull(out);
        this.err = checkNotNull(err);
    }

    public StreamSet(final InputStream in, final PrintStream out) {
        this(in, out, out);
    }

    public InputStream getInput() {
        return in;
    }

    public boolean isOutputCombined() {
        return out == err;
    }

    public PrintStream getOutput(final OutputType type) {
        checkNotNull(type);

        switch (type) {
        case OUT:
            return out;

        case ERR:
            return err;
        }

        // unreachable
        throw new Error();
    }

    public void flush() {
        Flushables.flushQuietly(out);

        if (!isOutputCombined()) {
            Flushables.flushQuietly(err);
        }
    }

    public void close() {
        Closeables.close(in, out);

        if (!isOutputCombined()) {
            Closeables.close(err);
        }
    }

    private String objectId(final Object obj) {
        assert obj != null;
        return obj.getClass().getSimpleName() + "@" + System.identityHashCode(obj);
    }

    public String toString() {
        return String.format("%s{in=%s, out=%s, err=%s}", getClass().getSimpleName(), objectId(in), objectId(out),
                objectId(err));
    }

    /**
     * Create a new stream set as {@link System} is currently configured.
     */
    public static StreamSet system() {
        return new StreamSet(System.in, System.out, System.err);
    }

    /**
     * Install the given stream set as the {@link System} streams.
     */
    public static void system(final StreamSet streams) {
        assert streams != null;

        System.setIn(streams.in);
        System.setOut(streams.out);
        System.setErr(streams.err);
    }

    /**
     * The original {@link System} streams (as they were when this class loads).
     */
    public static final StreamSet SYSTEM = system();

    /**
     * The {@link System} streams as file streams, for a better chance of non-buffered I/O.
     */
    public static final StreamSet SYSTEM_FD = new StreamSet(new FileInputStream(FileDescriptor.in),
            new PrintStream(new FileOutputStream(FileDescriptor.out)),
            new PrintStream(new FileOutputStream(FileDescriptor.err)));
}