Java文件编译出现 “编码 GBK 的不可映射字符”

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Demo6 {

    /*
     * @param args
     * 
     * @在记事本中验证 测试好用
     * 
     * @author 周周
     * 
     * @version 1.1
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub

        // 定义一个可以存放四只狗的对象数组
        DogNew dogs[] = new DogNew[4];

        // 从控制台输入各个狗的信息
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);

        for (int i = 0; i < 4; i++) {
            dogs[i] = new DogNew();

            System.out.println("请输入第" + (i + 1) + "只狗的名字");

            // 从控制台读取狗名

            String name = br.readLine();

            // 将名字赋给对象
            dogs[i].setName(name);

            System.out.println("请输入第" + (i + 1) + "只狗的体重");
            String s_weight = br.readLine();
            // 只要编译器看到readLine，程序就会停在那里等你输入，你不输入它不往下进行
            // 但是，readLine读进来之后总是一个字符串，依照要求，需要自己强转一下
            float weight = Float.parseFloat(s_weight);
            // 将名字赋给对象
            dogs[i].setWeight(weight);

        }
        // 计算总体重
        float allWeight = 0;
        for (int i = 0; i < 4; i++) {
            allWeight += dogs[i].getWeight();// getWeight()指取出对应狗的体重。把它累计给allWeight这个变量
        }
        // 计算平均体重
        float avgWeight = allWeight / dogs.length;// 这里没有除以4.而是直接计算出对象数组的大小了

        System.out.println("总体重：" + allWeight + "   平均体重：" + avgWeight);

        // 找出体重最大的狗
        // 假设 第一只狗体重最大
        float maxWeight = dogs[0].getWeight();
        int maxIndex = 0;
        // 按顺序和后面的狗比较
        for (int i = 1; i < dogs.length; i++) {
            if (maxWeight < dogs[i].getWeight()) {
                // 修改
                maxWeight = dogs[i].getWeight();
                maxIndex = i;
            }

        }
        System.out.println("体重最大的狗是第" + (maxIndex + 1) + "     体重是"
                + dogs[maxIndex].getWeight());
    }
}

// 定义一个狗类
class DogNew {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public float getWeight() {
        return weight;
    }

    public void setWeight(float weight) {
        this.weight = weight;
    }

    private float weight;

}

javac -encoding utf-8 xxxxx.java