Java运行shell脚本

利用Runtime.execute方法，我们可以在Java程序中运行Linux的Shell脚本，或者执行其他程序。参考了互联网上的这篇文章：http://lee79.javaeye.com/blog/418549（感谢一下），我重新整理了代码。
现在通过CommandHelper.execute方法可以执行命令，该类实现代码如下：
package javaapplication3;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
*
* @author chenshu
*/
public class CommandHelper {

//default time out, in millseconds
public static int DEFAULT_TIMEOUT;
public static final int DEFAULT_INTERVAL = 1000;
public static long START;


public static CommandResult exec(String command) throws IOException, InterruptedException {
Process process = Runtime.getRuntime().exec(command);
CommandResult commandResult = wait(process);
if (process != null) {
process.destroy();
}
return commandResult;
}

private static boolean isOverTime() {
return System.currentTimeMillis() - START >= DEFAULT_TIMEOUT;
}

private static CommandResult wait(Process process) throws InterruptedException, IOException {
BufferedReader errorStreamReader = null;
BufferedReader inputStreamReader = null;
try {
errorStreamReader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
inputStreamReader = new BufferedReader(new InputStreamReader(process.getInputStream()));

//timeout control
START = System.currentTimeMillis();
boolean isFinished = false;

for (;;) {
if (isOverTime()) {
CommandResult result = new CommandResult();
result.setExitValue(CommandResult.EXIT_VALUE_TIMEOUT);
result.setOutput("Command process timeout");
return result;
}

if (isFinished) {
CommandResult result = new CommandResult();
result.setExitValue(process.waitFor());

//parse error info
if (errorStreamReader.ready()) {
StringBuilder buffer = new StringBuilder();
String line;
while ((line = errorStreamReader.readLine()) != null) {
buffer.append(line);
}
result.setError(buffer.toString());
}

//parse info
if (inputStreamReader.ready()) {
StringBuilder buffer = new StringBuilder();
String line;
while ((line = inputStreamReader.readLine()) != null) {
buffer.append(line);
}
result.setOutput(buffer.toString());
}
return result;
}

try {
isFinished = true;
process.exitValue();
} catch (IllegalThreadStateException e) {
// process hasn't finished yet
isFinished = false;
Thread.sleep(DEFAULT_INTERVAL);
}
}

} finally {
if (errorStreamReader != null) {
try {
errorStreamReader.close();
} catch (IOException e) {
}
}

if (inputStreamReader != null) {
try {
inputStreamReader.close();
} catch (IOException e) {
}
}
}
}
}

CommandHelper类使用了CommandResult对象输出结果错误信息。该类实现代码如下：
package javaapplication3;
/**
*
* @author chenshu
*/
public class CommandResult {
public static final int EXIT_VALUE_TIMEOUT=-1;

private String output;

void setOutput(String error) {
output=error;
}

String getOutput(){
return output;
}

int exitValue;

void setExitValue(int value) {
exitValue=value;
}

int getExitValue(){
return exitValue;
}

private String error;

/**
* @return the error
*/
public String getError() {
return error;
}

/**
* @param error the error to set
*/
public void setError(String error) {
this.error = error;
}
}


现在看看调用代码的演示（main函数接受一个超时参数）：
public static void main(String[] args) {
try {
int timeout = Integer.parseInt(args[0]);
CommandHelper.DEFAULT_TIMEOUT = timeout;
CommandResult result = CommandHelper.exec("mkdir testdir");
if (result != null) {
System.out.println("Output:" + result.getOutput());
System.out.println("Error:" + result.getError());
}
} catch (IOException ex) {
System.out.println("IOException:" + ex.getLocalizedMessage());
} catch (InterruptedException ex) {
System.out.println("InterruptedException:" + ex.getLocalizedMessage());
}
}

结果会创建一个testdir目录。

我尝试用这种方法创建通过ssh登录到远程机器，遇到两个问题：
1）如果希望没有人机对话方式，则需要使用命令sshpass -p password ssh user@targetIP 'command'
2) 在NetBeans上直接运行工程是不行的，因为权限不够,需要在终端里运行java javaapplication3.Main
3) 很多命令不能运行，只有如pwd等命令可以运行，原因还不清楚，最好改用Ganymed SSH-2库或者其他类似Java库，我会在下一篇文章中介绍如何使用。