Json之java-Jackson

他山之石

jackson annotations注解详解

Maven依赖

<!--Jackson 2.x ,有三个jar,jackson-core-2.x.x.jar（核心jar包）,
                                   jackson-annotations-2.x.x.jar（该包提供Json注解支持）
                                   jackson-databind-2.x.x.jar
                                   annotations依赖core,databind依赖annotations，所以pom中只需要加databind的依赖即可
                                   -->

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.3</version>
        </dependency>

实践代码

import cn.mamp.Json.User;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Test;

import java.io.IOException;

public class JacksonUse {
    @Test
    public void objectMapperUser() {
        ObjectMapper objectMapper = new ObjectMapper();
        User user = new User();
        user.setAge(123);
        try {
            // Obj -> String
            String userJsonStr = objectMapper.writeValueAsString(user);
            System.out.println(userJsonStr); // 默认序列化null值：{"name":null,"age":123}

            // String -> obj
            User u = objectMapper.readValue(userJsonStr, User.class);
            System.out.println(u);

        } catch (JsonProcessingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}