Java.lang.Process需要注意的问题

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Java中执行本地命令的接口方法有两种，一种是java.lang.Runtime获取Runtime环境执行exec方法，另一种是通过创建java.lang.ProcessBuilder实例，执行command方法，这两种方法都能创建Process对象获取Input、Output、Error流与本地进程通信。

java.lang.ProcessBuilder是Jdk 1.5中新添加的一个类，J2SE 1.5之前，都是由java.lang.Runtime来实现进程的控制管理。
无论通过哪种方法创建，都是获取了Process对象，但是ProcessBuilder可以通过redirectErrorStream（true）把错误流合并到InputStream流中。一般命令执行成功后，会从inputstream中输出，但在Windows操作系统上执行本地java命令，成功后从ErrorStream流输出，因此需要通过redirectErrorStream将ErrorStream合并到Inputstream中去。

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.util.Arrays;public class TestRuntime { public static void main(String[] args) throws IOException {   Process process=Runtime.getRuntime().exec(args);    exeProcess(process);  System.out.println("===============ProcessBuilder redirectErrorStream(false)======================");  Process process2= new ProcessBuilder().redirectErrorStream(false).command(Arrays.asList(args)).start();  exeProcess(process2);  System.out.println("===============ProcessBuilder redirectErrorStream(true)======================");  Process process3= new ProcessBuilder().redirectErrorStream(true).command(Arrays.asList(args)).start();  exeProcess(process3);   }  public static void exeProcess(Process process) throws IOException {    BufferedReader isr=new BufferedReader(new InputStreamReader(process.getInputStream()));  String line="";  while((line=isr.readLine())!=null)  {      System.out.println(line);  }  BufferedReader isr1=new BufferedReader(new InputStreamReader(process.getErrorStream()));  String line1="";  while((line1=isr1.readLine())!=null)  {      System.out.println("error:"+line1);  }  process.destroy();   }}

以上代码在eclipse中调试运行后为：

error:java version "1.8.0_45"
error:Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
error:Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode, sharing)
===============ProcessBuilder redirectErrorStream(false)======================
error:java version "1.8.0_45"
error:Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
error:Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode, sharing)
===============ProcessBuilder redirectErrorStream(true)======================
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode, sharing)

在Cmd模式下运行runnable jar为

Microsoft Windows [版本 6.2.9200]
(c) 2012 Microsoft Corporation。保留所有权利。

C:\Users\lili>cd c:\test

c:\test>java -jar newProcessTest.jar java -version
error:java version "1.8.0_45"
error:Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
error:Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode)
===============ProcessBuilder redirectErrorStream(false)======================
error:java version "1.8.0_45"
error:Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
error:Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode, sharing)
===============ProcessBuilder redirectErrorStream(true)======================
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b15)
Java HotSpot(TM) Client VM (build 25.45-b02, mixed mode, sharing)

c:\test>

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