Jackson忽略为空的字段

ゝ一纸荒年。 2022-11-14 14:54 224阅读 0赞

# 1.概述 #

如何在序列化Java类时将Jackson设置为忽略空字段。

# 2.忽略类中的空字段 #

jackjson允许在任何一个类上控制这种行为：

@JsonInclude(Include.NON_NULL)
    public class MyDto {  ... }

或更详细地在字段级别：

@Data
    public class MyDtoField { 
        @JsonInclude(JsonInclude.Include.NON_NULL)
        private String stringValue;
        private int intValue;
    }

@Test
        public void test22() throws JsonProcessingException { 
            ObjectMapper mapper = new ObjectMapper();
            MyDtoField dtoObject = new MyDtoField();
    
            String dtoAsString = mapper.writeValueAsString(dtoObject);
            System.out.println(dtoAsString);//{"intValue":0}
    
            assertThat(dtoAsString, containsString("intValue"));
            assertThat(dtoAsString, not(containsString("stringValue")));
        }

# 3.全局忽略空字段 #

Jackson还允许我们在ObjectMapper上全局配置此行为：

mapper.setSerializationInclusion(Include.NON_NULL);

@Data
    public class MyDtoGlobalField { 
        private String stringValue;
        private int intValue;
        private boolean booleanValue;
    }

@Test
    public void test23() throws JsonProcessingException { 
        ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        MyDtoGlobalField dtoObject = new MyDtoGlobalField();
    
        String dtoAsString = mapper.writeValueAsString(dtoObject);
        System.out.println(dtoAsString);//{"intValue":0,"booleanValue":false}
        assertThat(dtoAsString, containsString("intValue"));
        assertThat(dtoAsString, containsString("booleanValue"));
        assertThat(dtoAsString, not(containsString("stringValue")));
    }

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