Gson解析（3）——Map處理數據(上)

Map的存儲結構式Key/Value形式,Key 和 Value可以是普通類型,也可以是自己寫的JavaBean(本文),還可以是帶有泛型的List(下一篇博客).本例中您要重點看如何將Json轉回爲普通JavaBean對象時TypeToken的定義.

實體類:

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 + "]";
    }

}

測試類:

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將結果按先進先出順序排列
        map1.put(new Point(5, 6), "a");
        map1.put(new Point(8, 8), "b");
        String s = gson.toJson(map1);
        System.out.println(s);// 結果:[[{"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));
        }

    }
}

結果:

[[{"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]

文章轉自：http://blog.csdn.net/lk_blog/article/details/7685210

感謝博主的無私分享！