设置一个配置文件，用以注入自己的json工厂
@Configuration public class JsonConfig { @Bean public MappingJackson2HttpMessageConverter mappingJacksonHttpMessageConverter() { final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter(); ObjectMapper mapper = converter.getObjectMapper(); // 为mapper注册一个带有SerializerModifier的Factory，此modifier主要做的事情为：当序列化类型为array，list、set时，当值为空时，序列化成[] mapper.setSerializerFactory(mapper.getSerializerFactory().withSerializerModifier(new MyBeanSerializerModifier())); return converter; } }
再对需要处理的情况进行处理
public class MyBeanSerializerModifier extends BeanSerializerModifier { private JsonSerializer<Object> _nullArrayJsonSerializer = new MyNullArrayJsonSerializer(); private JsonSerializer<Object> _nullObjectJsonSerializer = new MyNullObjectJsonSerializer(); @Override public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) { // 循环所有的beanPropertyWriter for (int i = 0; i < beanProperties.size(); i++) { BeanPropertyWriter writer = beanProperties.get(i); // 判断字段的类型，如果是array，list，set则注册nullSerializer if (isArrayType(writer)) { //给writer注册一个自己的nullSerializer writer.assignNullSerializer(this.defaultNullArrayJsonSerializer()); }else if(isObjectType(writer)){ writer.assignNullSerializer(this.defaultNullObjectJsonSerializer()); } } return beanProperties; } private boolean isObjectType(BeanPropertyWriter writer) { Class<?> clazz = writer.getPropertyType(); return !clazz.isPrimitive() && !clazz.equals(String.class) && clazz.isAssignableFrom(Object.class); } // 判断是什么类型 protected boolean isArrayType(BeanPropertyWriter writer) { Class<?> clazz = writer.getPropertyType(); return clazz.isArray() || clazz.equals(List.class) || clazz.equals(Set.class); } protected JsonSerializer<Object> defaultNullArrayJsonSerializer() { return _nullArrayJsonSerializer; } protected JsonSerializer<Object> defaultNullObjectJsonSerializer() { return _nullObjectJsonSerializer; } }
