在项目开发中,我们返回的数据或者对象没有的时候一般直接返回的null
有数据时的返回值
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{ "flag" : true , "code" : "10000" , "msg" : "成功!" , "data" : { "id" : 32, "templateType" : 1, "templateName" : "我的测试模板1" , "freightName" : "我的测试标题1" , "listArea" : [ { "id" : 968, "templateId" : 32, "freightPrice" : 15, } ], "templateDescEntity" : { "id" : 1 "name" : "xxx" } } } |
没有数据时的返回值
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{ "flag" : true , "code" : "10000" , "msg" : "成功!" , "data" : { "id" : 32, "templateType" : 1, "templateName" : null , "freightName" : null , "listArea" : null , "templateDescEntity" : null } } |
这种情况下数据返回给前端,前端需要做大量的空值判断
如前端调使用属性data.templateDescEntity.id的时候就会直接报异常
此时我们可以使用返回值统一处理,配置如下
pom.xml添加
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< dependency > < groupId >com.fasterxml.jackson.core</ groupId > < artifactId >jackson-annotations</ artifactId > < version >2.9.5</ version > </ dependency > < dependency > < groupId >com.fasterxml.jackson.core</ groupId > < artifactId >jackson-databind</ artifactId > </ dependency > |
java类添加配置
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package com.ys.mall.core.product.config; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.databind.JsonSerializer; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.SerializerProvider; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Primary; import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder; import java.io.IOException; import java.lang.reflect.Field; import java.util.Collection; import java.util.List; import java.util.Map; import java.util.Objects; /** * 数据返回给前端时,设置null值默认为"" * * @author cgh * @date 2020/12/14 10:35 */ @Configuration public class JacksonConfig { @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 { String fieldName = jsonGenerator.getOutputContext().getCurrentName(); try { //反射获取字段类型 Field field = jsonGenerator.getCurrentValue().getClass().getDeclaredField(fieldName); if (CharSequence. class .isAssignableFrom(field.getType())) { //字符串型空值"" jsonGenerator.writeString( "" ); return ; } else if (Collection. class .isAssignableFrom(field.getType())) { //列表型空值返回[] jsonGenerator.writeStartArray(); jsonGenerator.writeEndArray(); return ; } else if (Map. class .isAssignableFrom(field.getType())) { //map型空值 或者 bean对象 返回{} jsonGenerator.writeStartObject(); jsonGenerator.writeEndObject(); return ; } } catch (NoSuchFieldException ignored) { } jsonGenerator.writeString( "" ); } }); return objectMapper; } } |
添加空值统一处理后的返回值
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{ "flag" : true , "code" : "10000" , "msg" : "成功!" , "data" : { "id" : 32, "templateType" : 1, "templateName" : "" , "freightName" : "" , "listArea" : [], "templateDescEntity" : {} } } |
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原文链接:https://juejin.cn/post/6989848776361902088