java - jackson 无法识别的字段

Question

我使用 jackson 将 JSON 转换为 Object 类。

JSON:

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

对象类:

class Test{
    public String aaa;
    public String bbb;
}

代码:

ObjectMapper mapper = new ObjectMapper();
Object obj = mapper.readValue(content, valueType);

我的代码抛出这样的异常:

org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "cccc" (Class com.isoftstone.banggo.net.result.GetGoodsInfoResult), not marked as ignorable

而且我不想在 Test 类中添加 Prop ，我只想让 jackson 将存在的值转换为 Test 中也存在的值。

Answer 1

Jackson 提供了几种不同的机制来配置“额外”JSON 元素的处理。以下是将 ObjectMapper 配置为非 FAIL_ON_UNKNOWN_PROPERTIES 的示例。

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;
}

有关其他方法，请参阅 http://wiki.fasterxml.com/JacksonHowToIgnoreUnknown