ObjectMapper

pojo对象转换成json对象

 package com.ttj.sso.server.controller;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;


public class JsonTest {

    protected static String getJson(Object obj) {
        ObjectMapper mapper = new ObjectMapper();
        // null替换为""
        mapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
            @Override
            public void serialize(Object arg0, JsonGenerator arg1, SerializerProvider arg2) throws IOException, JsonProcessingException {
                arg1.writeString("");
            }
        });
        String str = null;
        try {
            str = mapper.writeValueAsString(obj);
        } catch (JsonGenerationException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }


    public static void main(String[] args) {
        System.out.println(getJson(new TestObject()));//TestObject必须是POJO对象
    }

}

class TestObject {
    String name = "张三";
    String sex = null;

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

}

springboot 注入ObjectMapper 对象

@Bean
@Primary
@ConditionalOnMissingBean(ObjectMapper.class)
public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
    ObjectMapper objectMapper = builder.createXmlMapper(false).build();
    objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
        @Override
        public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider)
            throws IOException, JsonProcessingException {
            jsonGenerator.writeString("");
        }
    });
    // 不显示参数为空的配置
    //objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
    return objectMapper;
}

Converter对象

@Configuration
public class MyWebMvcConfigurer implements WebMvcConfigurer {

    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for (HttpMessageConverter<?> converter : converters) {
            // 解决controller返回普通文本中文乱码问题
            if (converter instanceof StringHttpMessageConverter) {
                ((StringHttpMessageConverter) converter).setDefaultCharset(StandardCharsets.UTF_8);
            }
            // 解决controller返回json对象中文乱码问题
            if (converter instanceof MappingJackson2HttpMessageConverter) {
                ((MappingJackson2HttpMessageConverter) converter).setDefaultCharset(StandardCharsets.UTF_8);
            }
        }
    }
}