fastjson、jackson、gson用法一览

水深无声 2023-09-29 01:14 58阅读 0赞

### 文章目录 ###

*  1 准备
 *  2 序列化
 *   *  2.1 fastjson
     *  2.2 jackson
     *  2.3 json
 *  3. 反序列化
 *   *  3.1 字符串反序列为Json对象
     *   *  3.1.1 fastjson
         *  3.1.2 jackson
         *  3.1.2 gson
     *  3.2 字符串反序列为Java对象
     *   *  3.2.1 fastjson
         *  3.2.2 jackson
         *  3.2.3 gson
     *  3.3 字符串反序列化成json数组
     *   *  3.3.1 fastjson
         *  3.3.2 jackson
         *  3.3.3 gson
     *  3.4 字符串反序列化成List
     *   *  3.4.1 fastjson
         *  3.4.2 jackson
         *  3.4.3 gson

# 1 准备 #

有如下类：

class Person {
        
    
        private String name;
        private int age;
    
        public Person() {
        }
    
        public Person(String name, int age) {
        
            this.name = name;
            this.age = age;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public int getAge() {
        
            return age;
        }
    
        public void setAge(int age) {
        
            this.age = age;
        }
    }

有如下对象：

Person person = new Person("张三", 23);
    String personStr = "{\"age\":23,\"name\":\"张三\"}";
    String personListStr = "[{\"age\":23,\"name\":\"张三\"}]";

# 2 序列化 #

## 2.1 fastjson ##

JSON.toJSONString(person);

美化json：

JSON.toJSONString(person, SerializerFeature.PrettyFormat);
    // 或者
    JSON.toJSONString(person, true);

## 2.2 jackson ##

objectMapper.writeValueAsString(person);

美化json：

objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(person);

## 2.3 json ##

Gson gson = new Gson();
    gson.toJson(person);

美化json：

Gson gson = new GsonBuilder().setPrettyPrinting().create();
    gson.toJson(person);

# 3. 反序列化 #

## 3.1 字符串反序列为Json对象 ##

### 3.1.1 fastjson ###

JSONObject jsonObject = JSON.parseObject(personStr);
    System.out.println(jsonObject.getString("name"));
    System.out.println(jsonObject.getInteger("age"));

### 3.1.2 jackson ###

JsonNode node = objectMapper.readTree(personStr);
    System.out.println(node.get("name").asText());
    System.out.println(node.get("age").asInt());

### 3.1.2 gson ###

JsonObject gsonObject = new JsonParser().parse(personStr).getAsJsonObject();
    System.out.println(gsonObject.get("name").getAsString());
    System.out.println(gsonObject.get("age").getAsInt());

## 3.2 字符串反序列为Java对象 ##

### 3.2.1 fastjson ###

Person person = JSON.parseObject(personStr, Person.class);

### 3.2.2 jackson ###

Person person = objectMapper.readValue(personStr, Person.class);

### 3.2.3 gson ###

Person person = new Gson().fromJson(personStr, Person.class);

## 3.3 字符串反序列化成json数组 ##

### 3.3.1 fastjson ###

JSONArray jsonArray = JSON.parseArray(personListStr);
    
     // 遍历
    for (Object item : jsonArray ) {
        
        JSONObject itemObject = (JSONObject) item;
        System.out.println(itemObject.getString("name"));
        System.out.println(itemObject.getInteger("age"));
    }

### 3.3.2 jackson ###

JsonNode jsonNode = objectMapper.readTree(personListStr);
    if (jsonNode.isArray()) {
        
        for (JsonNode item : jsonNode) {
        
            System.out.println(item.get("name").asText());
            System.out.println(item.get("age").asInt());
        }
    }

### 3.3.3 gson ###

JsonArray jsonArray = new JsonParser().parse(personListStr).getAsJsonArray();
    for (JsonElement jsonElement : jsonArray) {
        
        System.out.println(jsonElement.getAsJsonObject().get("name").getAsString());
        System.out.println(jsonElement.getAsJsonObject().get("age").getAsInt());
    }

## 3.4 字符串反序列化成List ##

### 3.4.1 fastjson ###

List<Person> personList = JSON.parseArray(personListStr, Person.class);
    List<Person> personList2 = JSON.parseObject(personListStr, new TypeReference<List<Person>>(){
        });

### 3.4.2 jackson ###

List<Person> personListByJackson = objectMapper.readValue(personListStr, new TypeReference<List<Person>>(){
        });

### 3.4.3 gson ###

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