使用Jackson自定义序列化操作（Jackson – Custom Serializer）

喜欢ヅ旅行 2024-03-23 18:26 36阅读 0赞

#### 目录 ####

*  Standard Serialization of an Object Graph
 *  Custom Serializer on the ObjectMapper
 *  Custom Serializer on the Class

--------------------

## Standard Serialization of an Object Graph ##

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class Item {
        
        public int id;
        public String itemName;
        public User owner;
    }

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class User {
        
        public int id;
        public String name;
    }

Item myItem = new Item(1, "theItem", new User(2, "theUser"));
    
    String serialized = new ObjectMapper().writeValueAsString(myItem);
    
    System.out.println(serialized);
    
    结果
    {
        "id":1,"itemName":"theItem","owner":{
        "id":2,"name":"theUser"}}

--------------------

## Custom Serializer on the ObjectMapper ##

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class Item {
        
        public int id;
        public String itemName;
        public User owner;
    }

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class User {
        
        public int id;
        public String name;
    }

public class ItemSerializer extends StdSerializer<Item> {
        
        public ItemSerializer() {
        
            this(null);
        }
        public ItemSerializer(Class<Item> t) {
        
            super(t);
        }
        @Override
        public void serialize(Item value, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException {
        
            jsonGenerator.writeStartObject();
            jsonGenerator.writeNumberField("id", value.id);
            jsonGenerator.writeStringField("itemName", value.itemName);
            jsonGenerator.writeNumberField("owner", value.owner.id);
            jsonGenerator.writeEndObject();
        }
    }

Item myItem = new Item(1, "theItem", new User(2, "theUser"));
    
    ObjectMapper mapper = new ObjectMapper();
    SimpleModule module = new SimpleModule();
    module.addSerializer(Item.class, new ItemSerializer());
    mapper.registerModule(module);
    
    String serialized = mapper.writeValueAsString(myItem);
    
    System.out.println(serialized);
    
    结果
    {
        "id":1,"itemName":"theItem","owner":2}

--------------------

## Custom Serializer on the Class ##

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    public class User {
        
        public int id;
        public String name;
    }

@Data
    @NoArgsConstructor
    @AllArgsConstructor
    @JsonSerialize(using = ItemSerializer.class)
    public class Item {
        
        public int id;
        public String itemName;
        public User owner;
    }

\-----------------------------------------------------------------------------读书笔记摘自 文章：**[Jackson – Custom Serializer][Jackson _ Custom Serializer]**

[Jackson _ Custom Serializer]: https://www.baeldung.com/jackson-custom-serialization