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(本文),还可以是带有泛型的List.
（GSON的GitHub项目页：https://github.com/google/gson）
JavaBean
本例中您要重点看如何将Json转回为普通JavaBean对象时TypeToken的定义.
实体类:
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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 + "]";
}
}
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测试类:
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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));
}
}
}
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结果:
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[[{"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]
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泛型List
实体类:
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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 + ", id="codetool">
测试类:
输出结果:
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