java 将输出重定向到文件方法

import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.File;

public class tmp
{
        public static void main(String args[]) throws Exception
        {
                File file = new File("tmp.txt");
                PrintStream ps = new PrintStream(file);

                ps.println("hello world");
                ps.flush();
                ps.close();

                File file2 = new File("tmp2.txt");
                PrintWriter writer = new PrintWriter(file2);
                writer.println("hello world2");
                writer.flush();
                writer.close();
        }
}