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用java启动windows命令行程序 (转载)

2011-07-08 15:09 363 查看

先请编译和运行下面程序： import java.util.*; import java.io.*; public class BadExecJavac2 { public static void main(String args[]) { try { Runtime rt = Runtime.getRuntime(); Process proc = rt.exec("javac"); int exitVal = proc.waitFor(); System.out.println("Process exitValue: " + exitVal); } catch (Throwable t){ t.printStackTrace(); } } } 我们知道javac命令，当不带参数运行javac程序时，它将输出帮助说明，为什么上面程序不产生任何输出并挂起，永不完成呢？java文档上说,由于有些本地平台为标准输入和输出流所提供的缓冲区大小有限,如果不能及时写入子进程的输入流或者读取子进程的输出流,可能导致子进程阻塞,甚至陷入死锁。所以，上面的程序应改写为： import java.util.*; import java.io.*; public class MediocreExecJavac { public static void main(String args[]) { try { Runtime rt = Runtime.getRuntime(); Process proc = rt.exec("javac"); InputStream stderr = proc.getErrorStream(); InputStreamReader isr = new InputStreamReader(stderr); BufferedReader br = new BufferedReader(isr); String line = null; System.out.println("<ERROR>"); while ( (line = br.readLine()) != null) System.out.println(line); System.out.println("</ERROR>"); int exitVal = proc.waitFor(); System.out.println("Process exitValue: " + exitVal); } catch (Throwable t){ t.printStackTrace(); } } } 下面是正确的输出： D:\java>java MediocreExecJavac <ERROR> Usage: javac <options> <source files> where possible options include: -g Generate all debugging info -g:none Generate no debugging info -g:{lines,vars,source} Generate only some debugging info -nowarn Generate no warnings -verbose Output messages about what the compiler is doing -deprecation Output source locations where deprecated APIs are used -classpath <path> Specify where to find user class files -cp <path> Specify where to find user class files -sourcepath <path> Specify where to find input source files -bootclasspath <path> Override location of bootstrap class files -extdirs <dirs> Override location of installed extensions -endorseddirs <dirs> Override location of endorsed standards path -d <directory> Specify where to place generated class files -encoding <encoding> Specify character encoding used by source files -source <release> Provide source compatibility with specified release -target <release> Generate class files for specific VM version -version Version information -help Print a synopsis of standard options -X Print a synopsis of nonstandard options -J<flag> Pass <flag> directly to the runtime system </ERROR> Process exitValue: 2 D:\java> 下面是一个更一般的程序，它用两个线程同步清空标准错误流和标准输出流，并能根据你所使用的windows操作系统选择windows命令解释器command.com或cmd.exe,然后执行你提供的命令。 import java.util.*; import java.io.*; class StreamGobbler extends Thread { InputStream is; String type; //输出流的类型ERROR或OUTPUT StreamGobbler(InputStream is, String type) { this.is = is; this.type = type; } public void run() { try { InputStreamReader isr = new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); String line=null; while ( (line = br.readLine()) != null) { System.out.println(type + ">" + line); System.out.flush(); } } catch (IOException ioe) { ioe.printStackTrace(); } } } public class GoodWindowsExec { public static void main(String args[]) { if (args.length < 1) { System.out.println("USAGE: java GoodWindowsExec <cmd>"); System.exit(1); } try { String osName = System.getProperty("os.name" ); System.out.println("osName: " + osName); String[] cmd = new String[3]; if(osName.equals("Windows XP") ||osName.equals("Windows 2000")) { cmd[0] = "cmd.exe" ; cmd[1] = "/C" ; cmd[2] = args[0]; } else if( osName.equals( "Windows 98" ) ) { cmd[0] = "command.com" ; cmd[1] = "/C" ; cmd[2] = args[0]; } Runtime rt = Runtime.getRuntime(); System.out.println("Execing " + cmd[0] + " " + cmd[1]+ " " + cmd[2]); Process proc = rt.exec(cmd); // any error message? StreamGobbler errorGobbler = new StreamGobbler(proc.getErrorStream(), "ERROR"); // any output? StreamGobbler outputGobbler = new StreamGobbler(proc.getInputStream(), "OUTPUT"); // kick them off errorGobbler.start(); outputGobbler.start(); // any error??? int exitVal = proc.waitFor(); System.out.println("ExitValue: " + exitVal); } catch (Throwable t){ t.printStackTrace(); } } } 下面是一个测试结果： D:\java>java GoodWindowsExec "copy Test.java Test1.java" osName: Windows XP Execing cmd.exe /C copy Test.java Test1.java OUTPUT>已复制 1 个文件。 ExitValue: 0 D:\java> 下面的测试都能通过(windows xp+jdk1.5) D:\java>java GoodWindowsExec dir D:\java>java GoodWindowsExec Test.java D:\java>java GoodWindowsExec regedit.exe D:\java>java GoodWindowsExec NOTEPAD.EXE D:\java>java GoodWindowsExec first.ppt D:\java>java GoodWindowsExec second.doc

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