import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;

public class Test17 {

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

        System.out.println("输出一条信息");
        
        FileOutputStream fos = new FileOutputStream("errors.txt");
        PrintStream ps = new PrintStream(fos);
        System.setOut(ps);

        System.out.println("再输出一条信息");
        
    }

}

------解决方案--------------------
自己看书找啊....