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;}@Overridepublic 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;}@Overridepublic 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}]

Json转换利器Gson之实例一-简单对象转化和带泛型的List转化 (http://blog.csdn.net/lk_blog/article/details/7685169)
Json转换利器Gson之实例二-Gson注解和GsonBuilder (http://blog.csdn.net/lk_blog/article/details/7685190)
Json转换利器Gson之实例三-Map处理(上) (http://blog.csdn.net/lk_blog/article/details/7685210)
Json转换利器Gson之实例四-Map处理(下) (http://blog.csdn.net/lk_blog/article/details/7685224)
Json转换利器Gson之实例五-实际开发中的特殊需求处理 (http://blog.csdn.net/lk_blog/article/details/7685237)
Json转换利器Gson之实例六-注册TypeAdapter及处理Enum类型 (http://blog.csdn.net/lk_blog/article/details/7685347)

实例代码下载: http://download.csdn.net/detail/lk_blog/4387822

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