使用GSON库将Java中的map键值对应结构对象转换为JSON

public class Point {   private int x;   private int y;    public Point(int x, int y) {     this.x = x;     this.y = y;   }    public int getX() {     return x;   }    public void setX(int x) {     this.x = x;   }    public int getY() {     return y;   }    public void setY(int y) {     this.y = y;   }    @Override   public String toString() {     return "Point [x=" + x + ", y=" + y + "]";   }  } 

import java.util.LinkedHashMap; import java.util.Map;  import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.reflect.TypeToken;  public class GsonTest3 {    public static void main(String[] args) {     Gson gson = new GsonBuilder().enableComplexMapKeySerialization()         .create();      Map<Point, String> map1 = new LinkedHashMap<Point, String>();// 使用LinkedHashMap将结果按先进先出顺序排列     map1.put(new Point(5, 6), "a");     map1.put(new Point(8, 8), "b");     String s = gson.toJson(map1);     System.out.println(s);// 结果:[[{"x":5,"y":6},"a"],[{"x":8,"y":8},"b"]]      Map<Point, String> retMap = gson.fromJson(s,         new TypeToken<Map<Point, String>>() {         }.getType());     for (Point p : retMap.keySet()) {       System.out.println("key:" + p + " values:" + retMap.get(p));     }     System.out.println(retMap);      System.out.println("----------------------------------");     Map<String, Point> map2 = new LinkedHashMap<String, Point>();     map2.put("a", new Point(3, 4));     map2.put("b", new Point(5, 6));     String s2 = gson.toJson(map2);     System.out.println(s2);      Map<String, Point> retMap2 = gson.fromJson(s2,         new TypeToken<Map<String, Point>>() {         }.getType());     for (String key : retMap2.keySet()) {       System.out.println("key:" + key + " values:" + retMap2.get(key));     }    } } 

[[{"x":5,"y":6},"a"],[{"x":8,"y":8},"b"]] key:Point [x=5, y=6] values:a key:Point [x=8, y=8] values:b {Point [x=5, y=6]=a, Point [x=8, y=8]=b} ---------------------------------- {"a":{"x":3,"y":4},"b":{"x":5,"y":6}} key:a values:Point [x=3, y=4] key:b values:Point [x=5, y=6] 

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}]