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.<p> </p>

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
+ "]";
}

}

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);
}
}

}
}

{"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}]