Jackson 使用

 

// 序列化出来的 JSON， 不包含值为 NULL 类型字段。

mapper.setSerializationInclusion(Include.NON_NULL);  

　　

 Jackson provides a few different mechanisms to configure handling of "extra" JSON elements. Following is an example of configuring the ObjectMapper to not FAIL_ON_UNKNOWN_PROPERTIES.

 出现这种 error， 一般是没有该字段造成的，或都是字段名字写错了。

import org.codehaus.jackson.annotate.JsonAutoDetect.Visibility;

import org.codehaus.jackson.annotate.JsonMethod;

import org.codehaus.jackson.map.DeserializationConfig;

import org.codehaus.jackson.map.ObjectMapper;



public class JacksonFoo

{

  public static void main(String[] args) throws Exception

  {

    // { "aaa":"111", "bbb":"222", "ccc":"333" }

    String jsonInput = "{ \"aaa\":\"111\", \"bbb\":\"222\", \"ccc\":\"333\" }";



    ObjectMapper mapper = new ObjectMapper().setVisibility(JsonMethod.FIELD, Visibility.ANY);

    mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);



    Test test = mapper.readValue(jsonInput, Test.class);

  }

}



class Test

{

  String aaa;

  String bbb;

}

　格式化日期代码如下：

mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));

 空值不显示：

 mapper.setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL);