傑克遜反序列化的錯誤處理

Question

我的問題很簡單：我有以下簡單的類：

public class Foo { 
    private int id = -1; 
    public void setId(int _id){ this.id = _id; } 
    public int getId(){ return this.id; } 
} 

，我試圖以處理以下JSON：

{ 
    "id": "blah" 
} 

顯然，這裏有一個問題（「blah」不能被解析爲int）

以前，Jackson拋出類似org.codehaus.jackson.map.JsonMappingException的東西：無法從String構造java.lang.Integer的實例值「胡說」：不是一個有效的整數值

我同意這一點，但我想註冊某個地方的東西，允許忽略這種類型的映射錯誤的。 我嘗試使用已註冊的DeserializationProblemHandler（請參閱here），但似乎只適用於未知屬性而不是反序列化問題。

你對這個問題有任何線索嗎？

Answer 1

我成功解決了我的問題，這要感謝Tatu from Jackson ML。

我不得不使用定製的非阻塞解串器在處理傑克遜每基本類型。 事情是這樣的工廠：

public class JacksonNonBlockingObjectMapperFactory { 

    /** 
    * Deserializer that won't block if value parsing doesn't match with target type 
    * @param <T> Handled type 
    */ 
    private static class NonBlockingDeserializer<T> extends JsonDeserializer<T> { 
     private StdDeserializer<T> delegate; 

     public NonBlockingDeserializer(StdDeserializer<T> _delegate){ 
      this.delegate = _delegate; 
     } 

     @Override 
     public T deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException { 
      try { 
       return delegate.deserialize(jp, ctxt); 
      }catch (JsonMappingException e){ 
       // If a JSON Mapping occurs, simply returning null instead of blocking things 
       return null; 
      } 
     } 
    } 

    private List<StdDeserializer> jsonDeserializers = new ArrayList<StdDeserializer>(); 

    public ObjectMapper createObjectMapper(){ 
     ObjectMapper objectMapper = new ObjectMapper(); 

     SimpleModule customJacksonModule = new SimpleModule("customJacksonModule", new Version(1, 0, 0, null)); 
     for(StdDeserializer jsonDeserializer : jsonDeserializers){ 
      // Wrapping given deserializers with NonBlockingDeserializer 
      customJacksonModule.addDeserializer(jsonDeserializer.getValueClass(), new NonBlockingDeserializer(jsonDeserializer)); 
     } 

     objectMapper.registerModule(customJacksonModule); 
     return objectMapper; 
    } 

    public JacksonNonBlockingObjectMapperFactory setJsonDeserializers(List<StdDeserializer> _jsonDeserializers){ 
     this.jsonDeserializers = _jsonDeserializers; 
     return this; 
    } 
} 

然後調用它像這樣（傳爲解串器，只有那些你想成爲非阻塞）：

JacksonNonBlockingObjectMapperFactory factory = new JacksonNonBlockingObjectMapperFactory(); 
factory.setJsonDeserializers(Arrays.asList(new StdDeserializer[]{ 
    // StdDeserializer, here, comes from Jackson (org.codehaus.jackson.map.deser.StdDeserializer) 
    new StdDeserializer.ShortDeserializer(Short.class, null), 
    new StdDeserializer.IntegerDeserializer(Integer.class, null), 
    new StdDeserializer.CharacterDeserializer(Character.class, null), 
    new StdDeserializer.LongDeserializer(Long.class, null), 
    new StdDeserializer.FloatDeserializer(Float.class, null), 
    new StdDeserializer.DoubleDeserializer(Double.class, null), 
    new StdDeserializer.NumberDeserializer(), 
    new StdDeserializer.BigDecimalDeserializer(), 
    new StdDeserializer.BigIntegerDeserializer(), 
    new StdDeserializer.CalendarDeserializer() 
})); 
ObjectMapper om = factory.createObjectMapper(); 

Answer 2

你可能想要讓你的控制器處理問題通過添加處理這個特定的異常

@ExceptionHandler(HttpMessageNotReadableException.class) 
@ResponseBody 
public String handleHttpMessageNotReadableException(HttpMessageNotReadableException ex) 
{ 
    JsonMappingException jme = (JsonMappingException) ex.getCause(); 
    return jme.getPath().get(0).getFieldName() + " invalid"; 
} 

當然的方法，該線

JsonMappingException jme = (JsonMappingException) ex.getCause(); 

可能會拋出一些情況下，類轉換異常，但我還沒有遇到過他們呢。

Answer 3

創建一個簡單的映射：

@Provider 
@Produces(MediaType.APPLICATION_JSON) 
public class JSONProcessingErroMapper implements ExceptionMapper<InvalidFormatException> { 

@Override 
public Response toResponse(InvalidFormatException ex) { 
    return Response.status(400) 
      .entity(new ClientError("[User friendly message]")) 
      .type(MediaType.APPLICATION_JSON) 
      .build(); 
} 

}