JSON解析三種方式：

下面簡單說明一下三種解析方式如何使用

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公共代碼

json文檔內(nèi)容：

{
  "vegetable":["茄子", "番茄", "青菜"],
  "fruit":[
    {"name":"橘子","color":"橘色", "weight":"1"},
    {"name":"葡萄","color":"紫色", "weight":"2"},
    {"name":"蘋果","color":"紅色", "weight":"3"}
  ],
  "food":"米飯"
}

為了方便，在java直接用String形式書寫：

String jsonString = "{\n" +
                "  \"vegetable\":[\"茄子\", \"番茄\", \"青菜\"],\n" +
                "  \"fruit\":[\n" +
                "    {\"name\":\"橘子\",\"color\":\"橘色\", \"weight\":\"1\"},\n" +
                "    {\"name\":\"葡萄\",\"color\":\"紫色\", \"weight\":\"2\"},\n" +
                "    {\"name\":\"蘋果\",\"color\":\"紅色\", \"weight\":\"3\"}\n" +
                "  ],\n" +
                "  \"food\":\"米飯\"\n" +
                "}";

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三種解析方式用例

org.json 解析

JSONObject jsonObject = new JSONObject(jsonString);
JSONArray vegetable = jsonObject.getJSONArray("vegetable");
vegetable.getString(1);//番茄
JSONArray fruit = jsonObject.getJSONArray("fruit");
fruit.getJSONObject(2).getString("color");//紅色
jsonObject.getString("food");//米飯

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Gson 解析

• 根據(jù)Json文檔創(chuàng)建對應(yīng)的JavaBean類，不需要寫全json文檔中的屬性（Android Studio可以通過插件自動創(chuàng)建）

public class EatBean {

    @SerializedName("food")
    private String food;
    @SerializedName("fruit") //這個注釋對應(yīng)json文檔中對應(yīng)屬性key
    private List<FruitBean> fruitBeanList; //如果沒有上面的注釋，那這里的變量名稱必須要對應(yīng)json文檔
    @SerializedName("vegetable")
    private List<String> vegetableList;

    public String getFood() {
        return food;
    }

    public void setFood(String food) {
        this.food = food;
    }

    public List<FruitBean> getFruitBeanList() { // get方法名可以改
        return fruitBeanList;
    }

    public void setFruit(List<FruitBean> fruitBeanList) { // set方法名改了Jackson解析會出錯，因為這個方法不會調(diào)用到，盡量不要改
        this.fruitBeanList = fruitBeanList;
    }

    public List<String> getVegetableList() {
        return vegetableList;
    }

    public void setVegetable(List<String> vegetableList) {
        this.vegetableList = vegetableList;
    }

    public static class FruitBean {

        @SerializedName("color")
        private String color;
        @SerializedName("name")
        private String name;
        @SerializedName("weight")
        private String weight;

        public String getColor() {
            return color;
        }

        public void setColor(String color) {
            this.color = color;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getWeight() {
            return weight;
        }

        public void setWeight(String weight) {
            this.weight = weight;
        }
    }
}

• 導(dǎo)入Gson庫

implementation 'com.google.code.gson:gson:2.8.0'

• Java代碼

Gson gson = new Gson();
EatBean eatBean = gson.fromJson(jsonString, EatBean.class);

這樣json就被解析成了一個對象，使用gson解析時JavaBean對象不需要全部的屬性都和json文檔一一對應(yīng)，按需編寫即可，不需要的屬性可以不寫。

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Jackson 解析

• 根據(jù)json文檔創(chuàng)建對應(yīng)的JavaBean類，可以參考上面，和Gson解析有所區(qū)別的是，json文檔中所有屬性必須寫到JavaBean中的

• 導(dǎo)入Jackson庫
  在網(wǎng)下下載jackson解析的jar庫導(dǎo)入項目即可

implementation files('libs/jackson-all-1.9.2.jar')

• Java代碼

ObjectMapper objectMapper = new ObjectMapper();
EatBean eatBean = objectMapper.readValue(jsonString, EatBean.class);