当class1对象通过反射在另一个class2中被私有声明时，如何访问class1的私有变量的值

Question

我试图在通过课程作为对象到函数后访问部门的私有字段。系是课程中的一个私有变量。解决方案必须是通用的，因为这是一个反思练习。在运行时，存储对象函数不知道传递的是哪种类型的对象，所以也不能使用类型强制转换。这是部门类:

public class Department{
  private String departmentName;
  private Teacher departmentHOD;
}

这是课程:

public class Course {
  private String courseNumber;
  private String semesterName;
  private String courseName;
  private Department offeringDepartment;
  private Teacher[] courseInstructors;
  private int sectionNumbers;
}

在main I传递过程中的函数void storeObject(Object o):

void storeObject(Object o)
{
 //in this function i need to extract all possible primitive datatype objects and save them in a data base
Class classForStorage = o.getClass();
Field[] publicFields = classForStorage.getDeclaredFields();//.getFields()
    for (int i = 0; i < publicFields.length; i++) 
    {   //  making private ones accessible
        publicFields[i].setAccessible(true);
        //Getting name and type of all attributes in the class one by one
        String fieldName = publicFields[i].getName();
        Class typeClass = publicFields[i].getType();
        String fieldType = typeClass.getName();
       ......//after this i access values by datatype and store in sql
       //but it only works for primitive data types
    }

我不能访问departname使用类似:

  publicFields[i].getType().getDeclaredFields()[0].setAccessible(true);
  value =(String)publicFields[i].getType().getDeclaredFields()[0].get(obj); 

这给了我非法访问异常

如何从courseInstructor数组中获取值

Answer 1

你想太多了。

void printObject( Object o ) {
    for ( Field fld : o.getClass().getDeclaredFields() ) {
        fld.setAccessible( true );
        System.out.println( fld.get( o ) );
    }
}

如果您需要您的方法在字段是数组时表现不同，请使用isArray。

void printObject( Object o ) {
    for ( Field fld : o.getClass().getDeclaredFields() ) {
        fld.setAccessible( true );
        Object oFldVal = fld.get( o );
        if ( fld.getType().isArray() ) {
            int iLen = Arrays.getLength( oFldVal );
            for ( int i = 0; i < iLen; ++i ) {
                printObject( Arrays.get( oFldVal, i ) );
            }
        } else {
            System.println( oFldVal );
        }
    }
}

Answer 2

Edit: "via reflection"在此答案发布后被添加到问题标题中。如果解决方案必须使用反射，则此答案不适用。

你寻找的通用解是:

 public class Course {
   private String courseNumber;
   private String semesterName;
   private String courseName;
   private Department offeringDepartment;
   private Teacher[] courseInstructors;
   private int sectionNumbers;
   //add a getter to Course 
   public Department getDepartment() {
     return offeringDepartment
   }
}

检索部门使用

Course course = new Course();
Department department = course.getDepartment();

如果'o'对象是'Course'的一个实例，你可以:

//cast object to Course and use getter 
((Course)o).getDepartment();