Gson用法

Posted 2020-12-11 guaosky

记录下最近对Gson的使用方法，待完善。。

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1. 创建一个Gson对象

Gson gson = new GsonBuilder().serializeNulls().create();

serializeNulls()：序列化null值字段，因为Gson默认不序列化空值：

Configure Gson to serialize null fields. By default, Gson omits all fields that are null during serialization.

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2. 解析示例

String str = "{"apple":{"weight":12,"color":"red"},"people":{"name":"xiaoming","age":18}}"

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方法一： 解析成JSONObject形式

JsonObject o = gson.fromJson(str, JsonObject.class);
JsonElement element = o.get("people");
JsonElement element1 = o.get("apple");
People people1 = gson.fromJson(element, People.class);
Apple apple1 = gson.fromJson(element1, Apple.class);

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方法二：解析成新JavaBean

新建JavaBean：BianTai.java

注意：如果JavaBean的字段名与Json字符串的键名不一样需要@SerializedName("json键名")来指定值的反序列化

@Data
@ToString
public class BianTai {

    private Apple apple;
    @Data
    private static class Apple{
        private Integer weight;
        private String color;
    }

    private People people;
    @Data
    private static class People{
        private String name;
        private Integer age;
    }
}

直接解析成BianTai

BianTai bianTai = gson.fromJson(str, BianTai.class);

结果

BianTai(apple=BianTai.Apple(weight=12, color=null), people=BianTai.People(name=xiaoming, age=18))