Json转换利器Gson之实例三-Map处理(上)

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(下一篇博客).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 + "]";

}

}

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));

}

}

}

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]

实例源码：Gson