使用ProcessBuilder调用外部命令，并返回大量结果
在网上常见的用Java调用外部命令返回结果的方法是：
?????? process? =runtime.exec(cmd）
?????? is? =? process.getInputStream();?
?????? isr=new? InputStreamReader(is);?
?????? br? =new? BufferedReader(isr);?
?????? while(? (line? =? br.readLine())? !=? null? )?
?????? {?
?????????? out.println(line);?
?????????? out.flush();?
?????? }?
这种方法在遇到像cvs checkout modules这样不能马上返回结果的命令来说是无效的，不仅得不到返回结果，进程也会终止。其原因是，process在没有来得及gegtInputStream是，调用了BufferedReader.readLine其返回结果是null，也就是说循环一开始就会停止。因此想要正常运行只能直接读取process.getInputStream()，如下：
import java.io.*;
/**
?*??
?*? @author tyrone
?*
?*/
public class CMDExecute
{
?/**
? * @param cmd?
? * @return
? * @throws IOException
? */
?public synchronized String run(String[] cmd,String workdirectory) throws IOException{
??
??String line=null;
??String result="";
??????? try {
??????????? ProcessBuilder builder = new ProcessBuilder(cmd);
??????????? //set working directory
??????????? if (workdirectory!=null)
??????????? ?builder.directory(new File(workdirectory));
??????????? builder.redirectErrorStream(true);
??????????? Process process = builder.start();
??????????? InputStream in=process.getInputStream();
???????????????
?????????byte[] re=new byte[1024];
?????????while (in.read(re)!= -1) {
?????????? ??System.out.println(new String(re));
????????????? result = result + new String(re);
????????? }
???????? ?in.close();
??????? } catch (Exception ex) {
??????????? ex.printStackTrace();
??????? }
????? return result;
?}
?/**
? * @param args=cvs?log? */
?public static void main(String[] args){
??String result=null;
??CMDExecute cmdexe=new CMDExecute();
??try {??
???result= cmdexe.run(args,"D://MyProject//colimas//axis_c");
???System.out.println(result);
???}catch ( IOException ex ){
????ex.printStackTrace();
???}
??
?}
}
经过测试，本方法可以运行返回大量结果的应用程序。
