执行non-Java processes命令行的工具ExecHelper

在Java程序里执行操作命令行工具类：

    public static void main(String[] args) {

        try {
            /*String file = ExecHelper.exec(
                new String[]{"XXXX"}, "GBK"
            ).getOutput();

            String hello = ExecHelper.execUsingShell(
                "echo 'Hello World'"
            ).getOutput();*/

            ExecHelper helper = ExecHelper.execUsingShell("java -version", "GBK");
            System.out.println(helper.getResult());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

输出结果：

java version "1.6.0_37"
Java(TM) SE Runtime Environment (build 1.6.0_37-b06)
Java HotSpot(TM) Client VM (build 20.12-b01, mixed mode, sharing)

ExecHelper代码实现：

package com.yzu.zhang.utils;

import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;

/**
 * Convenience methods for executing non-Java processes.
 * @since ostermillerutils 1.06.00
 */
public final class ExecHelper {

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray), null);
    }

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray, String[] envp) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray, envp), null);
    }

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray, String[] envp, File dir) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray, envp), null);
    }

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray, String charset) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray), charset);
    }

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray, String[] envp, String charset) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray, envp), charset);
    }

    /**
     * Executes the specified command and arguments in a separate process, and waits for the
     * process to finish.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper exec(String[] cmdarray, String[] envp, File dir, String charset) throws IOException {
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray, envp), charset);
    }

    /**
     * Executes the specified command using a shell.  On windows uses cmd.exe or command.exe.
     * On other platforms it uses /bin/sh.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper execUsingShell(String command) throws IOException {
        return execUsingShell(command, null);
    }

    /**
     * Executes the specified command using a shell.  On windows uses cmd.exe or command.exe.
     * On other platforms it uses /bin/sh.
     * @since ostermillerutils 1.06.00
     */
    public static ExecHelper execUsingShell(String command, String charset) throws IOException {
        if (command == null) throw new NullPointerException();
        String[] cmdarray;
        String os = System.getProperty("os.name");
        if (os.equals("Windows 95") || os.equals("Windows 98") || os.equals("Windows ME")){
            cmdarray = new String[]{"command.exe", "/C", command};
        } else if (os.startsWith("Windows")){
            cmdarray = new String[]{"cmd.exe", "/C", command};
        } else {
            cmdarray = new String[]{"/bin/sh", "-c", command};
        }
        return new ExecHelper(Runtime.getRuntime().exec(cmdarray), charset);
    }

    /**
     * Take a process, record its standard error and standard out streams, wait for it to finish
     *
     * @param process process to watch
     * @throws SecurityException if a security manager exists and its checkExec method doesn't allow creation of a subprocess.
     * @throws IOException - if an I/O error occurs
     * @throws NullPointerException - if cmdarray is null
     * @throws IndexOutOfBoundsException - if cmdarray is an empty array (has length 0).
     *
     * @since ostermillerutils 1.06.00
     */
    private ExecHelper(Process process, String charset) throws IOException {
        StringBuffer output = new StringBuffer();
        StringBuffer error = new StringBuffer();

        Reader stdout;
        Reader stderr;

        if (charset == null){
            // This is one time that the system charset is appropriate,
            // don't specify a character set.
            stdout = new InputStreamReader(process.getInputStream());
            stderr = new InputStreamReader(process.getErrorStream());
        } else {
            stdout = new InputStreamReader(process.getInputStream(), charset);
            stderr = new InputStreamReader(process.getErrorStream(), charset);
        }
        char[] buffer = new char[1024];

        boolean done = false;
        boolean stdoutclosed = false;
        boolean stderrclosed = false;
        while (!done){
            boolean readSomething = false;
            // read from the process's standard output
            if (!stdoutclosed && stdout.ready()){
                readSomething = true;
                int read = stdout.read(buffer, 0, buffer.length);
                if (read < 0){
                    readSomething = true;
                    stdoutclosed = true;
                } else if (read > 0){
                    readSomething = true;
                    output.append(buffer, 0, read);
                }
            }
            // read from the process's standard error
            if (!stderrclosed && stderr.ready()){
                int read = stderr.read(buffer, 0, buffer.length);
                if (read < 0){
                    readSomething = true;
                    stderrclosed = true;
                } else if (read > 0){
                    readSomething = true;
                    error.append(buffer, 0, read);
                }
            }
            // Check the exit status only we haven't read anything,
            // if something has been read, the process is obviously not dead yet.
            if (!readSomething){
                try {
                    this.status = process.exitValue();
                    done = true;
                } catch (IllegalThreadStateException itx){
                    // Exit status not ready yet.
                    // Give the process a little breathing room.
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException ix){
                        process.destroy();
                        throw new IOException("Interrupted - processes killed");
                    }
                }
            }
        }

        this.output = output.toString();
        this.error = error.toString();
    }

    /**
     * The output of the job that ran.
     *
     * @since ostermillerutils 1.06.00
     */
    private String output;

    /**
     * Get the output of the job that ran.
     *
     * @return Everything the executed process wrote to its standard output as a String.
     *
     * @since ostermillerutils 1.06.00
     */
    public String getOutput(){
        return output;
    }

    /**
     * The error output of the job that ran.
     *
     * @since ostermillerutils 1.06.00
     */
    private String error;

    /**
     * Get the error output of the job that ran.
     *
     * @return Everything the executed process wrote to its standard error as a String.
     *
     * @since ostermillerutils 1.06.00
     */
    public String getError(){
        return error;
    }

    /**
     * The status of the job that ran.
     *
     * @since ostermillerutils 1.06.00
     */
    private int status;

    /**
     * Get the status of the job that ran.
     *
     * @return exit status of the executed process, by convention, the value 0 indicates normal termination.
     *
     * @since ostermillerutils 1.06.00
     */
    public int getStatus(){
        return status;
    }

    public String getResult(){
        if(!StringUtils.isBlank(output, error)){
            return output + "\n\n" +error;
        }
        if(StringUtils.isNotBlank(output)){
            return output;
        }
        if(StringUtils.isNotBlank(error)){
            return error;
        }
        return null;
    }
}