java读取txt有乱码！！求解决！！

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class Daone {   
    public static void main(String[] args) {   
        File file = new File("www.txt");   
        try {   
            FileReader f = new FileReader(file);   
            BufferedReader reader = new BufferedReader(f);   
            String str = reader.readLine();   
            while (str != null) {   
                System.out.println(str);   
                str = reader.readLine();   
            }   
        } catch (FileNotFoundException e) {   
            e.printStackTrace();   
        } catch (IOException e) {   
            e.printStackTrace();   
        }   
    }   
  
}  
读取的文件出来有乱码现象，求高手指教！！！谢谢！！
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