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=newInputStreamReader(is);
br=newBufferedReader(isr);
while((line=br.readLine())!=null)
{
out.println(line);
out.flush();
}
这种方法在碰到像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。