Json到具有类的Java对象 <?> 成员变量

Question

public class A {

    private Class<?> dataType;
    public Class<?> getDataType() {
        return dataType;
    }
    public void setDataType(Class<?> dataType) {
        this.dataType = dataType;
    }

}
public class B {

   public static void main(String[] args) {

       try {
            File file = new File( "fileName.json");
            A a = new ObjectMapper().readValue(file, A.class);
          } catch (IOException io) {
                io.printStackTrace();
            }
   }
}

• Contents in fileName.json file : { "dataType" : "java.lang.String" }

• I got error : org.codehaus.jackson.map.JsonMappingException: Can not access private java.lang.Class() (from class java.lang.Class; failed to set access: Can not make a java.lang.Class constructor accessible.

• Is there wrong representation of data in json file, if yes then can any one suggest me what will be correct notation of class A in json file.

Answer 1

• I got the solution : We have to use Jackson annotation for this. So rewrite class A.

import org.codehaus.jackson.annotate.JsonCreator;

import org.codehaus.jackson.annotate.JsonProperty;

public class A {

private Class<?> dataType;
public Class<?> getDataType() {
    return dataType;
}
public void setDataType(Class<?> dataType) {
    this.dataType = dataType;
}

@JsonCreator
public A(@JsonProperty("dataType") String dataType)
{ 
    try {
        this.dataType = Class.forName(dataType);
    } catch (ClassNotFoundException c) {
        c.printStackTrace();
    }
}

}