多线程调用多线程的方法 Runtime与ProcessBuilder

一般我们使用Java运行其他类中的方法的时候，无论是静态调用还是动态调用，都是在当前的进程中执行的。也就是只有一个Java虚拟机实例在运行。有时候需要通过Java代码启动多个Java子进程，这样做会消耗些资源，但是程序变得更稳定。因为新启动的进程是在不同的虚拟机中运行的。

在Windows中，一个虚拟机就是一个

有两种方式调用一个进程

1、System.exec

子进程：

 package org.zln.thread;

 import java.io.File;

 import java.io.IOException;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestFile {

     public static void main(String[] args)  {

         try {

             File file = new File("D:\\my.txt");

             file.createNewFile();

             System.out.println("被调用成功!");

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestFile.java

主进程：

 package org.zln.thread;

 import java.io.IOException;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestRuntime {

     public static void main(String[] args) {

         String rootPath = "E:\\GitHub\\tools\\JavaEEDevelop\\out\\production\\Lesson1_JavaSe_Demo1";

         String mainPath = "org.zln.thread.TestFile";

         String command = "java -classpath "+rootPath+" "+mainPath;

         Runtime runtime = Runtime.getRuntime();

         try {

             System.out.println(command);

             runtime.exec(command);

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestRuntime.java

调用发现在指定目录下创建了文件，但是并没有在控制台输出信息。因为TestFile子进程并没有自己的控制台，改进代码

 package org.zln.thread;

 import java.io.*;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestRuntime {

     public static void main(String[] args) {

         String rootPath = "E:\\GitHub\\tools\\JavaEEDevelop\\out\\production\\Lesson1_JavaSe_Demo1";

         String mainPath = "org.zln.thread.TestFile";

         String command = "java -classpath "+rootPath+" "+mainPath;

         Runtime runtime = Runtime.getRuntime();

         try {

             System.out.println(command);

             Process process = runtime.exec(command);

             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new BufferedInputStream(process.getInputStream())));

             String line;

             while ((line = bufferedReader.readLine())!=null){

                 System.out.println("子进程输出："+line);

             }

             bufferedReader.close();

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestRuntime.java

这里不知为何，在IDE中运行，输出的是乱码，在控制台运行则不是乱码

既然父进程可以获取到子进程的输出，那么父进程如何发送消息给子进程呢？

子进程修改：

 package org.zln.thread;

 import java.io.BufferedReader;

 import java.io.File;

 import java.io.IOException;

 import java.io.InputStreamReader;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestFile {

     public static void main(String[] args)  {

         try {

             File file = new File("D:\\my.txt");

             file.createNewFile();

             System.out.println("被调用成功!");

             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

             System.out.println("父进程输入信息："+bufferedReader.readLine());

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestFile.java

父进程修改：

 package org.zln.thread;

 import java.io.*;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestRuntime {

     public static void main(String[] args) {

         String rootPath = "E:\\GitHub\\tools\\JavaEEDevelop\\out\\production\\Lesson1_JavaSe_Demo1";

         String mainPath = "org.zln.thread.TestFile";

         String command = "java -classpath "+rootPath+" "+mainPath;

         Runtime runtime = Runtime.getRuntime();

         try {

             System.out.println(command);

             Process process = runtime.exec(command);

             /*向子进程输入*/

             BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(process.getOutputStream()));

             bufferedWriter.write("Hello 子进程!");

             bufferedWriter.close();/*必须现在就关闭，否则无法向子进程输入信息*/

             /*获取子进程输出*/

             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new BufferedInputStream(process.getInputStream())));

             String line;

             while ((line = bufferedReader.readLine())!=null){

                 System.out.println("子进程输出："+line);

             }

             bufferedReader.close();

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestRuntime.java

2、使用ProcessBuilder建立子进程

 package org.zln.thread;

 import java.io.*;

 /**

  * Created by coolkid on 2015/6/21 0021.

  */

 public class TestProcessBuilder {

     public static void main(String[] args) throws IOException {

         ProcessBuilder processBuilder = new ProcessBuilder("java","org.zln.thread.TestFile");

         /*设置工作目录*/

         processBuilder.directory(new File("E:\\GitHub\\tools\\JavaEEDevelop\\out\\production\\Lesson1_JavaSe_Demo1"));

         Process process = processBuilder.start();

          /*向子进程输入*/

         BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(process.getOutputStream()));

         bufferedWriter.write("Hello 子进程!");

         bufferedWriter.close();/*必须现在就关闭，否则无法向子进程输入信息*/

             /*获取子进程输出*/

         BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new BufferedInputStream(process.getInputStream())));

         String line;

         while ((line = bufferedReader.readLine())!=null){

             System.out.println("子进程输出："+line);

         }

         bufferedReader.close();

     }

 }

E:\GitHub\tools\JavaEEDevelop\Lesson1_JavaSe_Demo1\src\org\zln\thread\TestProcessBuilder.java

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多线程调用多线程的方法 Runtime与ProcessBuilder

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巴特西

多线程 调用多线程的方法 Runtime与ProcessBuilder

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多线程调用多线程的方法 Runtime与ProcessBuilder