Json转换利器Gson之实例四-Map处理(下)

Map的存储结构式Key/Value形式,Key 和 Value可以是普通类型,也可以是自己写的JavaBean(上一篇博客),还可以是带有泛型的List(本文).本例中您要重点看如何将Json转回 为带泛型的对象List,并且List中的泛型对象有多种实体.

 

 

实体类:

 

 

 

import java.util.Date;

public class Student {
    private int id;
    private String name;
    private Date birthDay;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Date getBirthDay() {
        return birthDay;
    }

    public void setBirthDay(Date birthDay) {
        this.birthDay = birthDay;
    }

    @Override
    public String toString() {
        return "Student [birthDay=" + birthDay + ", id=" + id + ", name="
                + name + "]";
    }

}

 

 

 

public class Teacher {
    private int id;

    private String name;

    private String title;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return "Teacher [id=" + id + ", name=" + name + ", title=" + title
                + "]";
    }

}

 

测试类:

 

 

 

package com.tgb.lk.demo.gson.test4;

import java.util.ArrayList;
import java.util.Date;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class GsonTest4 {
    public static void main(String[] args) {
        Student student1 = new Student();
        student1.setId(1);
        student1.setName("李坤");
        student1.setBirthDay(new Date());

        Student student2 = new Student();
        student2.setId(2);
        student2.setName("曹贵生");
        student2.setBirthDay(new Date());

        Student student3 = new Student();
        student3.setId(3);
        student3.setName("柳波");
        student3.setBirthDay(new Date());

        List<Student> stulist = new ArrayList<Student>();
        stulist.add(student1);
        stulist.add(student2);
        stulist.add(student3);

        Teacher teacher1 = new Teacher();
        teacher1.setId(1);
        teacher1.setName("米老师");
        teacher1.setTitle("教授");

        Teacher teacher2 = new Teacher();
        teacher2.setId(2);
        teacher2.setName("丁老师");
        teacher2.setTitle("讲师");
        List<Teacher> teacherList = new ArrayList<Teacher>();
        teacherList.add(teacher1);
        teacherList.add(teacher2);

        Map<String, Object> map = new LinkedHashMap<String, Object>();
        map.put("students", stulist);
        map.put("teachers", teacherList);

        Gson gson = new Gson();
        String s = gson.toJson(map);
        System.out.println(s);

        System.out.println("----------------------------------");

        Map<String, Object> retMap = gson.fromJson(s,
                new TypeToken<Map<String, List<Object>>>() {
                }.getType());

        for (String key : retMap.keySet()) {
            System.out.println("key:" + key + " values:" + retMap.get(key));
            if (key.equals("students")) {
                List<Student> stuList = (List<Student>) retMap.get(key);
                System.out.println(stuList);
            } else if (key.equals("teachers")) {
                List<Teacher> tchrList = (List<Teacher>) retMap.get(key);
                System.out.println(tchrList);
            }
        }

    }
}

输出结果:

 

 

{"students": [{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:48:19 PM"}, {"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 9:48:19 PM"}, {"id":3,"name":"柳波","birthDay":"Jun 22, 2012 9:48:19 PM"}],"teachers": [{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲 师"}]}
----------------------------------
key:students values: [{id=1.0, name=李坤, birthDay=Jun 22, 2012 9:48:19 PM}, {id=2.0, name=曹贵 生, birthDay=Jun 22, 2012 9:48:19 PM}, {id=3.0, name=柳 波, birthDay=Jun 22, 2012 9:48:19 PM}]
[{id=1.0, name= 李坤, birthDay=Jun 22, 2012 9:48:19 PM}, {id=2.0, name=曹贵 生, birthDay=Jun 22, 2012 9:48:19 PM}, {id=3.0, name=柳 波, birthDay=Jun 22, 2012 9:48:19 PM}]
key:teachers values:[{id=1.0, name=米老师, title=教授}, {id=2.0, name=丁老师, title=讲师}]
[{id=1.0, name=米老师, title=教授}, {id=2.0, name=丁老师, title=讲师}]