Java解析Json字符串--数组或列表

Json示例：

[
    {
        "age": 25,
        "gender": "female",
        "grades": "三班",
        "name": "露西",
        "weight": 51.3 },
    {
        "age": 26,
        "gender": "male",
        "grades": "三班",
        "name": "杰克",
        "weight": 66.5 },
    {
        "age": 25,
        "gender": "female",
        "grades": "三班",
        "name": "莉莉",
        "weight": 55 }
]

我们来解析一下这个Json字符串。

首先，因为此Json字符串最外边是由一个中括弧”[]”包裹，那么，最终我们会用数组或者列表来接收它。

接下来，我们能看到中括弧里边有三个同级的大括弧，并且每个大括弧里包含的内容是相同的，大括弧我们可以对应创建一个类，我们创建一个类Student.java，并对应大括弧内的元素，定义相应的成员变量，生成get/set方法。

我们生成的Student.java如下：

package com.bean;

/** * 学生 */
public class Student {

    private int age;//年龄
    private String gender;//性别，male/female
    private String grades;//班级
    private String name;//姓名
    private float weight;//体重

    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public String getGrades() {
        return grades;
    }
    public void setGrades(String grades) {
        this.grades = grades;
    }
    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;
    }

}

解析成数组或列表：

package com.test;

import java.util.ArrayList;
import java.util.List;

import net.sf.json.JSONArray;

import com.bean.Student;

public class Domain {

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {

        String jsonStr = "[{\"age\": 25,\"gender\": \"female\",\"grades\": \"三班\",\"name\": \"露西\",\"weight\": 51.3},{\"age\": 26,\"gender\": \"male\",\"grades\": \"三班\",\"name\": \"杰克\",\"weight\": 66.5},{\"age\": 25,\"gender\": \"female\",\"grades\": \"三班\",\"name\": \"莉莉\",\"weight\": 55}]";

        JSONArray jsonArray = JSONArray.fromObject(jsonStr);

        Student[] stus = new Student[3];
        List<Student> list = new ArrayList<Student>();

        stus = (Student[]) JSONArray.toArray(jsonArray, Student.class);//转换成数组
        list = (List<Student>) JSONArray.toCollection(jsonArray, Student.class);//转换成列表

    }
}

通过数组或者列表生成Json字符串：

package com.test;

import java.util.ArrayList;
import java.util.List;

import net.sf.json.JSONArray;

import com.bean.Student;

public class Domain {

    @SuppressWarnings("unchecked")
    public static void main(String[] args) {

        Student stu1 = new Student();
        Student stu2 = new Student();
        Student stu3 = new Student();

        stu1.setAge(25);
        stu1.setGender("female");
        stu1.setGrades("三班");
        stu1.setName("露西");
        stu1.setWeight(51.3f);

        stu2.setAge(26);
        stu2.setGender("male");
        stu2.setGrades("三班");
        stu2.setName("杰克");
        stu2.setWeight(66.5f);

        stu3.setAge(25);
        stu3.setGender("female");
        stu3.setGrades("三班");
        stu3.setName("莉莉");
        stu3.setWeight(55.0f);

        Student[] stus = new Student[3];
        List<Student> list = new ArrayList<Student>();

        stus[0] = stu1;
        stus[1] = stu2;
        stus[2] = stu3;

        list.add(stu1);
        list.add(stu2);
        list.add(stu3);

        String jsonStr1 = JSONArray.fromObject(stus).toString();
        String jsonStr2 = JSONArray.fromObject(list).toString();

        System.out.println(jsonStr1);
        System.out.println(jsonStr2);


    }
}