java Runtime Process调用可执行文件，子进程阻塞

我用java调用mencoder实施转码，但是转码过程中出现子进程阻塞，而且还是看了API才知道这个问题的。因为mencoder的控制台输出信息很多，把缓存区所有的空间占满了，所以程序不能执行后面的程序，mencoder就只能转码28秒的视频，所以需要建立线程及时清空缓存区。

新建一个类StreamGobble类：

 

package thss.jmencoder;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
public class StreamGobble extends Thread {
    InputStream is;
    String type;

    StreamGobble(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);
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
}

 

在main函数中调用Runtime/Process执行转码

 

String line = value.toString();
String[] str = line.split(" ");
String fOutput = null;
fOutput = str[3] + ".flv";
Process process = null;
try {
    Runtime runtime = Runtime.getRuntime();
    process = runtime .exec("mencoder -ofps 30000/1001 -vf harddup"
        + " /user/student/data/"+str[0]
        + " -ss "+str[1]+" -endpos "+str[2]+" -sws 2 -of lavf -ovc lavc -lavcopts "
        + "vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 "
        + "-nosound -srate 22050 -o /user/student/data/"+fOutput);
    new StreamGobble(process.getInputStream(), "INFO").start();
    new StreamGobble(process.getErrorStream(), "ERROR").start();
    int status = process.waitFor();
    System.out.println("Process exitValue: " + status);
    } catch (Throwable t) {
        t.getStackTrace();
    } finally {
        if (process == null)
            process.destroy();
        process = null;