Gson详解(二）

绝地灬酷狼 2023-10-02 14:44 2阅读 0赞

### 1.复杂Json转成对象 ###

比如：jsonString:\{“response”:\{“content”:"\\n\\t",“msg”:“成功”,“code”:“0”,“data\{“content”:”\\n\\t",“VIN”:“LDC12345678901234”\},“cmd”:“ScanVINCode”\}\}

Gson解析

Gson gson = new Gson();
                roodBean = gson.fromJson(jsonString, VinBean.class);
                if (roodBean != null) {
        
                    responseBean = roodBean.getResponse();
                    if (responseBean != null) {
        
                        dataBean = responseBean.getData();
                        if (dataBean != null) {
        
                            tvReciveData.setText("获取" + responseBean.getMsg() + "\nvin:" + dataBean.getVIN());
                        }
                    }
                }

VinBean

/**
     * Description:Vin号的Bean类
     * AUTHOR: Champion Dragon
     * created at 2019/7/9
     **/
    public class VinBean {
        
       /* json字符串： formatted:{
            "response": {
                "content": "\n\t",
                        "msg": "成功",
                        "code": "0",
                        "data":    {"content": "\n\t","VIN": "LDC12345678901234"},
                "cmd": "ScanVINCode"
            }
        }*/
     
        private ResponseBean response;
     
        public ResponseBean getResponse() {
        
            return response;
        }
     
        public void setResponse(ResponseBean response) {
        
            this.response = response;
        }
     
        /**
         * content :
         * msg : 成功
         * code : 0
         * data : {"content":"\n\t","VIN":"LDC12345678901234"}
         * cmd : ScanVINCode
         */
        public static class ResponseBean {
        
            private String content;
            private String msg;
            private String code;
     
            private DataBean data;
            private String cmd;
     
            public String getContent() {
        
                return content;
            }
     
            public void setContent(String content) {
        
                this.content = content;
            }
     
            public String getMsg() {
        
                return msg;
            }
     
            public void setMsg(String msg) {
        
                this.msg = msg;
            }
     
            public String getCode() {
        
                return code;
            }
     
            public void setCode(String code) {
        
                this.code = code;
            }
     
            public DataBean getData() {
        
                return data;
            }
     
            public void setData(DataBean data) {
        
                this.data = data;
            }
     
            public String getCmd() {
        
                return cmd;
            }
     
            public void setCmd(String cmd) {
        
                this.cmd = cmd;
            }
     
            /**
             * content :
             * VIN : LDC12345678901234
             */
     
            public static class DataBean {
        
                private String content;
                private String VIN;
     
                public String getContent() {
        
                    return content;
                }
     
                public void setContent(String content) {
        
                    this.content = content;
                }
     
                public String getVIN() {
        
                    return VIN;
                }
     
                public void setVIN(String VIN) {
        
                    this.VIN = VIN;
                }
            }
        }
    }

### 2.json数组转Gson ###

"muser": [{
        "name": "zhangsan","age": "10","phone": "11111","email": "11111@11.com"},...]

#### 2.1JsonArray遍历 ####

//Json的解析类对象
    JsonParser parser = new JsonParser();
    //将JSON的String 转成一个JsonArray对象
    JsonArray jsonArray = parser.parse(strByJson).getAsJsonArray();Gson gson = new Gson();
    ArrayList userBeanList = new ArrayList<>();//加强for循环遍历JsonArray
    for (JsonElement user : jsonArray) {
        
    //使用GSON，直接转成Bean对象
    UserBean userBean = gson.fromJson(user, UserBean.class);
    userBeanList.add(userBean);

#### 2.2直接转成list对象数组 ####

### 解析的数组字符串外面多一个大括号 `response` ###

{
           [
       {
        
        "jylsh": "HZTYQ20180119074",
        "hphm": "浙A5J592",
        "hpzl": "大型汽车",
        "jycs": "1",
        "jyxm": "F1,F4",
        "sqsj": "20180119154701",
        "hpzlcode": "01"
       },
       {
        
        "jylsh": "HZTYQ20180130054",
        "hphm": "浙A3183",
        "hpzl": "警用汽车",
        "jycs": "2",
        "jyxm": "F4",
        "sqsj": "20180130134051",
        "hpzlcode": "23"
       },
       {
        
        "jylsh": "20180204151749",
        "hphm": "浙AQ90K3",
        "hpzl": "小型汽车",
        "jycs": "",
        "jyxm": "F4",
        "sqsj": "20180204151749",
        "hpzlcode": "02"
       }
    
    ]   }

CarListResponsebean carListResponsebean = GsonUtils.fromJson(response, CarListResponsebean.class);
    List<CarListItemBean> data = carListResponsebean.getData();

![img][]![img][img 1]

#### 2.3通过Gson中TypeToken转成list对象 ####

解析的数组字符串外面少一个大括号

[{
        "name":"Tom","age":"10"}, {
        "name":"Lucy","age":"11"}, {
        "name":"Lily","age":"11"}]

List<Person> people = gson.fromJson(jsonData, new TypeToken<List<Person>>(){
        }.getType());

## 三.GsonUtils工具类 ##

public class GsonUtil {
        
        private static final Gson GSON = createGson(true);
     
        private static final Gson GSON_NO_NULLS = createGson(false);
     
        private GsonUtil() {
        
            throw new UnsupportedOperationException("u can't instantiate me...");
        }
     
        /**
         * 创建Gson对象
         */
        private static Gson createGson(final boolean serializeNulls) {
        
            final GsonBuilder builder = new GsonBuilder();
            if (serializeNulls) {
        
                builder.serializeNulls();//是否序列化空值
            }
    //打开Export注解，但打开了这个注解,副作用，要转换和不转换都要加注解(造成json转换失败）一般千万别用
            builder.excludeFieldsWithoutExposeAnnotation()
                    .setDateFormat("yyyy-MM-dd HH:mm:ss")//序列化日期格式  "yyyy-MM-dd"
     
    //.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)//会把字段首字母大写
    //需要结合注解使用，有的字段在1.0的版本的时候解析，但0.1版本不解析
    //              .setVersion(1.0)  
                    .setPrettyPrinting(); //自动格式化换行
            return builder.create();
        }
     
        //获取gson解析器
        public static Gson getGson() {
        
            return getGson(true);
        }
     
        /**
         * 是否序列化空值
         */
        public static Gson getGson(final boolean serializeNulls) {
        
            return serializeNulls ? GSON_NO_NULLS : GSON;
        }
     
        //对象转换为json
        public static String toJson(Object object) {
        
            return toJson(object, true);
        }
     
        public static String toJson(final Object object, final boolean includeNulls) {
        
            return includeNulls ? GSON.toJson(object) : GSON_NO_NULLS.toJson(object);
        }
     
     
        //JSON转换为对象1--普通类型
        public static <T> T fromJson(String json, Class<T> classOfT) {
        
            return GSON.fromJson(json, classOfT);
        }
     
        //JSON转换为对象-针对泛型的类型
        public static <T> T fromJson(String json, Type typeOfT) {
        
            return GSON.fromJson(json, typeOfT);
        }
     
        public static <T> T fromJson(final Reader reader, final Class<T> type) {
        
            return GSON.fromJson(reader, type);
        }
     
        public static <T> T fromJson(final Reader reader, final Type type) {
        
            return GSON.fromJson(reader, type);
        }
     
        /**
         * @param reader JsonReader（位于Gson包中）  
         *InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
         *               JsonReader jsonReader = new JsonReader(inputStreamReader);
         * @param type   json将要转换的类型
         * @return T 实例类型
         **/
        public static <T> T fromJson(final JsonReader reader, final Type type) {
        
            return GSON.fromJson(reader, type);
        }
     
        /**
         * 转成list,解决泛型在编译期类型被擦除导致报错
         */
        public static <T> List<T> jsonToList(String json, Class<T> cls) {
        
            List<T> list = new ArrayList<T>();
            JsonArray array = new JsonParser().parse(json).getAsJsonArray();
            for (final JsonElement elem : array) {
        
                list.add(GSON.fromJson(elem, cls));
            }
            return list;
        }
     
        /**
         * 转成list中有map的
         */
        public static <T> List<Map<String, T>> GsonToListMaps(String gsonString) {
        
            return GSON.fromJson(gsonString, new TypeToken<List<Map<String, T>>>() {
        
            }.getType());
        }
     
        /**
         * 转成map的
         */
        public static <T> Map<String, T> GsonToMaps(String gsonString) {
        
            return GSON.fromJson(gsonString, new TypeToken<Map<String, T>>() {
        
            }.getType());
        }
    }

[img]: https://img-blog.csdnimg.cn/20190822103506220.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3h4ZHcxOTky,size_16,color_FFFFFF,t_70
[img 1]: https://img-blog.csdnimg.cn/20190822103522867.png