Json字符串

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;

class Student {
    private String name;
    private int age;
    private String sex;
    public Student(String name, int age, String sex) {

        this.name = name;
        this.age = age;
        this.sex = sex;
    }
}
/**
 * 介绍以下Json字符串   数据的序列化
 * Student stu = new Student("sss", 20, "male");
 * Json格式的数据：  {"name":"sss", "age":20, "sex":"male"}
 * @Author huiman
 */

public class MyJson {
    /**
     * 获取所有的属性：getField
     * 把对象序列化成Json字符串
     * cls 类型的Class对象
     * @param <T>
     * @return
     */
    public static <T> String toJson(T obj, Class<T> cls) throws Exception {
        StringBuilder sb = new StringBuilder();
        sb.append("{");
        Field[] fields = cls.getDeclaredFields();//获取所有属性存入数组
        //异常放在循环外
        try {
            for (int i = 0; i < fields.length; i++) {
                String name = fields[i].getName(); //获取成员变量的名字
                Field f2 = cls.getDeclaredField(name); //获取每一个属性
                f2.setAccessible(true);
                Object value = f2.get(obj); //get方法获得属性的值,注意参数，获取的是对象
                String str = name + ":" + value + ",";
                sb.append(str);//获取名字与值后用{括起来
            }
        }
         catch (Exception e) {
        }
        /**将index号元素的值改为ch
         * public void setCharAt(int index, char ch) {
        //        if ((index < 0) || (index >= count))
        //            throw new StringIndexOutOfBoundsException(index);
        //        value[index] = ch;
            }
        */
        sb.setCharAt(sb.length()-1,‘}‘);//setCharAt方法将最后一个改为"}"
        return sb.toString();//返回sb字符串
   }

    public static void main(String[] args) throws Exception {
        //将创建的Student对象存入数组
       Student[] students=new Student[3];//创建几个对象就要给对象赋值
       students[0]=new Student("sss", 20, "male");
       students[1]=new Student("mmm",10,"female");
       students[2]=new Student("aaa",30,"female");
       StringBuilder sb=new StringBuilder();
       sb.append("[");
       for(int i=0;i<students.length;i++){
           //将方法中产生的对象拼接起来
           sb.append(MyJson.toJson(students[i], Student.class));
           //对象之间用,隔开
           sb.append(",");
        }
        sb.setCharAt(sb.length()-1,‘]‘);
        System.out.println(sb);
    }
}