杰克逊 - 反序列化泛型类变量 [英] Jackson - Deserialize Generic class variable

问题描述

我错误地发布了这个问题。我在这里正确地发布了问题......

我得到一个json字符串作为HTTP响应。我知道它的结构。它如下所示：

  public class Json< T> {
 public Hits< T>命中; 
} 
 public class Hits< T> {
 public int found; 
 public int start; 
 public ArrayList< Hit< T>>击中; 
} 
 public class Hit< T> {
 public String id; 
 public Class< T>数据; 
 
 $ / code> 

data字段可以属于任何类别。我只会在运行时才知道它。我将把它作为参数。这就是我的反序列化过程。

  public< T> void deSerialize（Class< T> clazz）{
 ObjectMapper mapper = new ObjectMapper（）; 
 mapper.readValue（jsonString，new TypeReference< Json< T>>（）{}）; 
} 
  

但是我收到一个错误 -



无法从java.lang.class访问private java.lang.class.Class（）。无法设置访问权限。无法创建java.lang.Class构造函数

解决方案

您将需要构建 JavaType 明确地说，如果泛型类型只是动态可用的：



  //不要为每个请求创建新的ObjectMapper！ 
 final ObjectMapper mapper = new ObjectMapper（）; 
 
 public Json< T> void deSerialize（Class< T> clazz，InputStream json）{
 return mapper.readValue（json，
 mapper.getTypeFactory（）。constructParametricType（Json.class，clazz））; 
} 
  




I had posted the question wrongly. I am posting the question correctly here ...

I am getting a json string as a HTTP response. I know the structure of it. It is as follows:

public class Json<T> {
    public Hits<T> hits;
}
public class Hits<T> {
    public int found;
    public int start;
    public ArrayList<Hit<T>> hit;
}
public class Hit<T> {
    public String id;
    public Class<T> data;
}

The "data" field can belong to any class. I will know it at runtime only. I will get it as a parameter. This is how I am deserializing.

public <T> void deSerialize(Class<T> clazz) {
    ObjectMapper mapper = new ObjectMapper();
    mapper.readValue(jsonString,  new TypeReference<Json<T>>() {});
}

But I am getting an error -

cannot access private java.lang.class.Class() from java.lang.class. Failed to set access. Cannot make a java.lang.Class constructor accessible

解决方案

You will need to build JavaType explicitly, if generic type is only dynamically available:

// do NOT create new ObjectMapper per each request!
final ObjectMapper mapper = new ObjectMapper();

public Json<T> void deSerialize(Class<T> clazz, InputStream json) {
    return mapper.readValue(json,
      mapper.getTypeFactory().constructParametricType(Json.class, clazz));
}

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