Java执行shell命令
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Java执行shell命令
前言
java执行shell命令的方式有很多种，但是在应用的过程中，我们可能会遇上一些特殊的情况，导致执行脚本失败，不生效的场景。
一、案例
场景
- java服务，如果需要服务自动重启。那么我们通过java执行shell命令，使用常用jdk的方法：Runtime.getRuntime().exec(command)的方式，重启服务，可能会导致重启失败。
原因
- java执行本地命令启动的是一个子进程处理，默认情况下子进程与父进程I/O通过管道相连（ProcessBuilder.Redirect.PIPE）
- 当服务执行自身重启命令时，父进程关闭导致管道连接中断，将导致子进程也崩溃，而无法完成后续启动
解决方案
- 设置子进程的I/O源或目标将与当前进程的相同，两者相互独立
- 设置子进程IO输出重定向到指定文件
这里我们采用第一种解决方案
ProcessBuilder pb = new ProcessBuilder("service","java-service","restart");
pb.redirectOutput(ProcessBuilder.Redirect.INHERIT);
pb.redirectError(ProcessBuilder.Redirect.INHERIT);
pb.redirectInput(ProcessBuilder.Redirect.INHERIT);
pb.start();
ProcessBuilder 也是J2SE1.5 就有了的类。此类用于创建操作系统进程，它提供一种启动和管理进程（也就是应用程序）的方法。在J2SE 1.5之前，都是由Process类处来实现进程的控制管理。
static ProcessBuilder.Redirect DISCARD
表示将丢弃子进程输出。
static ProcessBuilder.Redirect INHERIT
表示子进程I / O源或目标将与当前进程的相同。
static ProcessBuilder.Redirect PIPE
表示子进程I / O将通过管道连接到当前Java进程。
ProcessBuilder 可配置执行脚本的子进程I / O源或目标将与当前进程的相同。绑定之后，执行重启，就能成功，管道不会断开。
ProcessBuilder 可参考连接：
ProcessBuilder api
ProcessBuilder 中文文档
二、拓展
创建临时脚本，执行shell命令
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.11.0</version>
</dependency>
可直接复制使用，注意引入maven包
public static String runAndResult(String cmd)
StringBuilder sb = new StringBuilder();
BufferedReader br = null;
boolean execFlag = true;
String uuid = UUID.randomUUID().toString().replace("-","");
String tempFileName = "./temp" + uuid +".sh";
try
String osName = System.getProperty("os.name").toUpperCase(Locale.ENGLISH);
if (osName.matches("^(?i)LINUX.*$") || osName.contains("MAC"))
FileWriter execute_fw = new FileWriter(tempFileName);
BufferedWriter execute_bw=new BufferedWriter(execute_fw);
execute_bw.write(cmd + "\\n");
execute_bw.close();
execute_fw.close();
String command ="bash " + tempFileName;
Process p = Runtime.getRuntime().exec(command);
p.waitFor();
br = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while ((line = br.readLine()) != null)
sb.append(System.lineSeparator());
sb.append(line);
br.close();
br = new BufferedReader(new InputStreamReader(p.getErrorStream()));
while ((line = br.readLine()) != null)
sb.append(System.lineSeparator());
sb.append(line);
if (line.length() > 0)
execFlag = false;
br.close();
if (execFlag)
else
throw new RuntimeException(sb.toString());
else
throw new RuntimeException("不支持的操作系统类型");
catch (Exception e)
log.error("执行失败",e);
finally
if (br != null)
try
br.close();
catch (IOException e)
log.error("io异常",e);
FileUtils.deleteQuietly(new File(tempFileName));
return sb.toString();
三、总结
实践是检验真理的唯一标准，工作生活中一定要多总结，记录。如果你觉得有用，点个赞吧。收藏一下也是不错的。
java程序执行,调用shell命令和shell脚本
坑呀！记得在start()之后， waitFor（）之前把缓冲区读出来打log，否则是阻塞缓冲区，没有输出的
package com.jikexueyuancrm.util;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.management.ManagementFactory;
import java.util.List;
import org.apache.log4j.Logger;
import com.jikexueyuancrm.controller.AnHui;
/**
* ShellUtils
* <ul>
* <strong>Check root</strong>
* <li>{@link ShellUtils#checkRootPermission()}</li>
* </ul>
* <ul>
* <strong>Execte command</strong>
* <li>{@link ShellUtils#execCommand(String, boolean)}</li>
* <li>{@link ShellUtils#execCommand(String, boolean, boolean)}</li>
* <li>{@link ShellUtils#execCommand(List, boolean)}</li>
* <li>{@link ShellUtils#execCommand(List, boolean, boolean)}</li>
* <li>{@link ShellUtils#execCommand(String[], boolean)}</li>
* <li>{@link ShellUtils#execCommand(String[], boolean, boolean)}</li>
* </ul>
*
* @author <a href="http://www.trinea.cn" target="_blank">Trinea</a> 2013-5-16
*/
/**
* @author yuan hai
* 使用Runtime.getRuntime().exec
*/
public class ShellUtils {
private static Logger log = Logger.getLogger(ShellUtils.class);
public static final String COMMAND_SU = "su";
public static final String COMMAND_SH = "sh";
public static final String COMMAND_EXIT = "exit\n";
public static final String COMMAND_LINE_END = "\n";
private ShellUtils() {
throw new AssertionError();
}
/**
* check whether has root permission
*
* @return
*/
public static boolean checkRootPermission() {
return execCommand("echo root", true, false).result == 0;
}
/**
* execute shell command, default return result msg
*
* @param command command
* @param isRoot whether need to run with root
* @return
* @see ShellUtils#execCommand(String[], boolean, boolean)
*/
public static CommandResult execCommand(String command, boolean isRoot) {
return execCommand(new String[] {command}, isRoot, true);
}
/**
* execute shell commands, default return result msg
*
* @param commands command list
* @param isRoot whether need to run with root
* @return
* @see ShellUtils#execCommand(String[], boolean, boolean)
*/
public static CommandResult execCommand(List<String> commands, boolean isRoot) {
return execCommand(commands == null ? null : commands.toArray(new String[] {}), isRoot, true);
}
/**
* execute shell commands, default return result msg
*
* @param commands command array
* @param isRoot whether need to run with root
* @return
* @see ShellUtils#execCommand(String[], boolean, boolean)
*/
public static CommandResult execCommand(String[] commands, boolean isRoot) {
return execCommand(commands, isRoot, true);
}
/**
* execute shell command
*
* @param command command
* @param isRoot whether need to run with root
* @param isNeedResultMsg whether need result msg
* @return
* @see ShellUtils#execCommand(String[], boolean, boolean)
*/
public static CommandResult execCommand(String command, boolean isRoot, boolean isNeedResultMsg) {
return execCommand(new String[] {command}, isRoot, isNeedResultMsg);
}
/**
* execute shell commands
*
* @param commands command list
* @param isRoot whether need to run with root
* @param isNeedResultMsg whether need result msg
* @return
* @see ShellUtils#execCommand(String[], boolean, boolean)
*/
public static CommandResult execCommand(List<String> commands, boolean isRoot, boolean isNeedResultMsg) {
return execCommand(commands == null ? null : commands.toArray(new String[] {}), isRoot, isNeedResultMsg);
}
/**
* execute shell commands
*
*
* 最基础方法
* @param commands command array
* @param isRoot whether need to run with root
* @param isNeedResultMsg whether need result msg
* @return <ul>
* <li>if isNeedResultMsg is false, {@link CommandResult#successMsg} is null and
* {@link CommandResult#errorMsg} is null.</li>
* <li>if {@link CommandResult#result} is -1, there maybe some excepiton.</li>
* </ul>
*/
public static CommandResult execCommand(String[] commands, boolean isRoot, boolean isNeedResultMsg) {
int result = -1;
if (commands == null || commands.length == 0) {
return new CommandResult(result, null, null);
}
Process process = null;
BufferedReader successResult = null;
BufferedReader errorResult = null;
StringBuilder successMsg = null;
StringBuilder errorMsg = null;
DataOutputStream os = null;
try {
process = Runtime.getRuntime().exec(isRoot ? COMMAND_SU : COMMAND_SH);
os = new DataOutputStream(process.getOutputStream());
for (String command : commands) {
if (command == null) {
continue;
}
// donnot use os.writeBytes(commmand), avoid chinese charset error
os.write(command.getBytes());
os.writeBytes(COMMAND_LINE_END);
os.flush();
}
os.writeBytes(COMMAND_EXIT);
os.flush();
// get command result
if (isNeedResultMsg) {
successMsg = new StringBuilder();
errorMsg = new StringBuilder();
successResult = new BufferedReader(new InputStreamReader(process.getInputStream()));
errorResult = new BufferedReader(new InputStreamReader(process.getErrorStream()));
String s;
while ((s = successResult.readLine()) != null) {
successMsg.append(s).append("\n");
}
while ((s = errorResult.readLine()) != null) {
errorMsg.append(s).append("\n");
}
}
result = process.waitFor();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (os != null) {
os.close();
}
if (successResult != null) {
successResult.close();
}
if (errorResult != null) {
errorResult.close();
}
} catch (IOException e) {
e.printStackTrace();
}
if (process != null) {
process.destroy();
}
}
log.info("result:"+result);
if( successMsg != null) log.info("successMsg:"+successMsg.toString());
if( errorMsg != null) log.info("errorMsg:"+errorMsg.toString());
return new CommandResult(result, successMsg == null ? null : successMsg.toString(), errorMsg == null ? null
: errorMsg.toString());
}
/**
* result of command
* <ul>
* <li>{@link CommandResult#result} means result of command, 0 means normal, else means error, same to excute in
* linux shell</li>
* <li>{@link CommandResult#successMsg} means success message of command result</li>
* <li>{@link CommandResult#errorMsg} means error message of command result</li>
* </ul>
*
* @author <a href="http://www.trinea.cn" target="_blank">Trinea</a> 2013-5-16
*/
public static class CommandResult {
/** result of command **/
public int result;
/** success message of command result **/
public String successMsg;
/** error message of command result **/
public String errorMsg;
public CommandResult(int result) {
this.result = result;
}
public CommandResult(int result, String successMsg, String errorMsg) {
this.result = result;
this.successMsg = successMsg;
this.errorMsg = errorMsg;
}
}
public static void main(String[] args) throws Exception {
//
String[] cmd=new String[]{"ps aux","pwd","ls -al"};
//执行shell命令
// execCommand(cmd,false, true);
//执行shell脚本
String[] script=new String[]{"/bin/bash /home/smgadmin/test/soyoung_comment/shell/crawler.sh start "};
execCommand(script,false, true);
//使用ProcessBuilder
// exeCmd("ps aux;ls -al;pwd");//执行linux命令
// exeCmd("dir&dir");//执行windows命令一行多命令用&分隔
}
//使用ProcessBuilder
/**
* @author yuan hai 2016年12月9日
* @param shell shell可以传入多个命令 ,例如:"ps aux;ls -al;pwd"
* @return
* @throws IOException
*/
public static int exeCmd(String shell) throws IOException {
int success = 0;
StringBuffer sb = new StringBuffer();
BufferedReader br = null;
// get name representing the running Java virtual machine.
String name = ManagementFactory.getRuntimeMXBean().getName();
String pid = name.split("@")[0];
try {
System.out.println("Starting to exec{ " + shell + " }. PID is: " + pid);
Process process = null;
//执行脚本时，不要加-c
// 当执行系统的命令时，才会加-c
//linux命令行
ProcessBuilder pb = new ProcessBuilder("/bin/bash", "-c", shell);
//windows命令行
// ProcessBuilder pb = new ProcessBuilder("cmd", "/c", shell);
pb.environment();
pb.redirectErrorStream(true); // merge error stream into standard stream
process = pb.start();
if (process != null) {
br = new BufferedReader(
new InputStreamReader(process.getInputStream(),"GBK"), 1024);
} else {
System.out.println("There is no PID found.");
}
sb.append("Ending exec right now, the result is：\n");
String line = null;
while (br != null && (line = br.readLine()) != null) {
sb.append(line).append("\n");
}
//记得在start()之后， waitFor（）之前把缓冲区读出来打log
process.waitFor();
} catch (Exception ioe) {
sb.append("Error occured when exec cmd：\n").append(ioe.getMessage()).append("\n");
} finally {
PrintWriter writer = null;
if (br != null) {
br.close();
}
try {
writer = new PrintWriter(System.out);
writer.write(sb.toString());
} catch (Exception e) {
log.error(e.getMessage(), e);
} finally {
writer.close();
}
success = 1;
}
return success;
}
}参考文章：
阿里大牛文章：
https://yq.aliyun.com/articles/2362
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