CommandProcessRunner.java

package info.vividcode;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.TimeUnit;

/**
 * すぐに実行終了するコマンド (外部プロセス) を実行するクラス。
 */
public class CommandProcessRunner  {

    private static boolean readOutputToBufferIfAvailable(BufferedInputStream out, ByteArrayOutputStream outBuf, byte[] buf) throws IOException {
        int available = out.available();
        if (available > 0) {
            int numReadBytes = out.read(buf);
            if (numReadBytes > 0) {
                outBuf.write(buf, 0, numReadBytes);
                return true;
            }
        }
        return false;
    }

    private static void readOutputToBufferWhileAvailable(BufferedInputStream out, ByteArrayOutputStream outBuf, byte[] buf) throws IOException, InterruptedException {
        while (true) {
            if (Thread.currentThread().isInterrupted()) throw new InterruptedException();

            boolean read = readOutputToBufferIfAvailable(out, outBuf, buf);
            if (!read) break;
        }
    }

    private static void readOutputToBufferUntilTerminated(BufferedInputStream out, ByteArrayOutputStream outBuf, byte[] buf) throws IOException, InterruptedException {
        while (true) {
            if (Thread.currentThread().isInterrupted()) throw new InterruptedException();

            int numReadBytes = out.read(buf);
            if (numReadBytes == -1) break;
            outBuf.write(buf, 0, numReadBytes);
        }
    }

    /**
     * 引数で指定されたプロセスを起動し、標準出力とエラー出力を読み込みながらプロセスの終了を待つ。
     * 終了コードと標準出力とエラー出力をまとめたオブジェクトを結果として返す。
     * @param command 実行するコマンドとその引数。
     * @return コマンドの実行結果。
     * @throws IOException プロセスとのやり取りで IO エラーが発生した場合に、そのエラーがそのまま投げられる。
     * @throws InterruptedException 実行中のスレッドが中断された場合に発生する。
     */
    public static CommandProcessRunner.Result execute(List<String> command) throws IOException, InterruptedException {
        byte[] buf = new byte[1024];
        ByteArrayOutputStream stdOutBuf = new ByteArrayOutputStream();
        ByteArrayOutputStream errOutBuf = new ByteArrayOutputStream();
        ProcessBuilder pb = new ProcessBuilder(command);
        Process process = pb.start();
        try {
            try (
                    BufferedInputStream stdOut = new BufferedInputStream(process.getInputStream());
                    BufferedInputStream errOut = new BufferedInputStream(process.getErrorStream())
            ) {
                while (true) {
                    readOutputToBufferWhileAvailable(stdOut, stdOutBuf, buf);
                    readOutputToBufferWhileAvailable(errOut, errOutBuf, buf);
                    boolean hasExited;
                    try {
                        hasExited = process.waitFor(10, TimeUnit.MICROSECONDS);
                    } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                        throw e;
                    }
                    if (hasExited) break;
                }
                readOutputToBufferUntilTerminated(stdOut, stdOutBuf, buf);
                readOutputToBufferUntilTerminated(errOut, errOutBuf, buf);
            }
            return new Result(process.exitValue(), stdOutBuf.toByteArray(), errOutBuf.toByteArray());
        } finally {
            if (process.isAlive()) {
                process.destroyForcibly();
                if (!Thread.currentThread().isInterrupted()) {
                    process.waitFor();
                }
            }
        }
    }

    public static class Result {
        public final int exitValue;
        public final byte[] standardOutput;
        public final byte[] errorOutput;

        public Result(int exitValue, byte[] standardOutput, byte[] errorOutput) {
            this.exitValue = exitValue;
            this.standardOutput = standardOutput;
            this.errorOutput = errorOutput;
        }
    }

}

Main.java

package info.vividcode;

import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.concurrent.*;

public class Main {

    /**
     * Windows マシンでスリープコマンドを実行する例。
     */
    public static void main(String[] args) throws InterruptedException, ExecutionException, TimeoutException {
        ExecutorService executorService = Executors.newSingleThreadExecutor();
        try {
            Future<CommandProcessRunner.Result> resultFuture = executorService.submit(() ->
                    CommandProcessRunner.execute(Arrays.asList("powershell", "-Command", "Start-Sleep -Seconds 5")));
            CommandProcessRunner.Result result;
            try {
                result = resultFuture.get(6, TimeUnit.SECONDS);
            } catch (TimeoutException e) {
                // 待ち時間を過ぎても終了しなかった場合はキャンセルする。
                resultFuture.cancel(true);
                throw e;
            }
            System.out.println("終了コード: " + result.exitValue);
            System.out.println("標準出力 : " + new String(result.standardOutput, Charset.forName("Shift_JIS")));
            System.out.println("エラー出力 : " + new String(result.errorOutput, Charset.forName("Shift_JIS")));
        } finally {
            executorService.shutdown();
        }
    }

}