1.实体上
@JsonInclude(Include.NON_NULL)
//将该标记放在属性上,如果该属性为NULL则不参与序列化
//如果放在类上边,那对这个类的全部属性起作用
//Include.Include.ALWAYS 默认
//Include.NON_DEFAULT 属性为默认值不序列化
//Include.NON_EMPTY 属性为 空(“”) 或者为 NULL 都不序列化
//Include.NON_NULL 属性为NULL 不序列化
2.代码上
ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(Include.NON_NULL);
//通过该方法对mapper对象进行设置,所有序列化的对象都将按改规则进行系列化
//Include.Include.ALWAYS 默认
//Include.NON_DEFAULT 属性为默认值不序列化
//Include.NON_EMPTY 属性为 空(“”) 或者为 NULL 都不序列化
//Include.NON_NULL 属性为NULL 不序列化
User user = new User(1,"",null);
String outJson = mapper.writeValueAsString(user);
System.out.println(outJson);
注意:只对VO起作用,Map List不起作用
ObjectMapper mapper = new ObjectMapper();mapper.setSerializationInclusion(Include.NON_NULL);Map map = new HashMap();map.put("a", null);map.put("b", "b");String ret_val = mapper.writeValueAsString(map);System.err.println(ret_val);Map m = mapper.readValue(ret_val, Map.class);System.err.println(m.get("a") + "|" + m.get("b"));输出:{"b":"b","a":null}null|b
VO vo = new VO();vo.setA(null);vo.setB("b");String ret_val1 = mapper.writeValueAsString(vo);System.err.println(ret_val1);VO v = mapper.readValue(ret_val1, VO.class);System.err.println(v.getA() + "|" + v.getB());<br>输出{"b":"b"}|b