Java 反思：对象不是声明的实例 class

Question

用户class

public class User {
        @Id
        @GeneratedValue(strategy=GenerationType.AUTO)
        private Long id;
        @Column(unique=true)
        private String username;
        @JsonIgnore
        private String password;
        private String firstName;
        private String lastName;
        private Date dob;
        private String motherName;
        private String fatherName;
        private String mobileNumber;
        @Column(unique=true)
        private String email;
        @ManyToOne
        @JoinColumn(name="role_id", nullable=false)
        private Role role;
        private String status;
    
        public void setPassword(String password) {
            this.password = PasswordEncoder.getEncodedPassword(password);
        }
    }

这是我的 UserRequest class

@Data
public class UserRequest {
    private Long id;
    private String username;
    private String password;
    private String firstName;
    private String lastName;
    private Date dob;
    private String motherName;
    private String fatherName;
    private String mobileNumber;
    private String email;
    private Long role;
    private String status;
}

我的复制方法存在于 Utility class

public static void copy(Object dest, Object source) throws IntrospectionException, IllegalArgumentException, IllegalAccessException,
        InvocationTargetException {
    BeanInfo beanInfo = Introspector.getBeanInfo(source.getClass());
    PropertyDescriptor[] pdList = beanInfo.getPropertyDescriptors();
    for (PropertyDescriptor pd : pdList) {
        Method writeMethod = null;
        Method readMethod = null;
        try {
            writeMethod = pd.getWriteMethod();
            readMethod = pd.getReadMethod();
        } catch (Exception e) {
        }

        if (readMethod == null || writeMethod == null) {
            continue;
        }

        Object val = readMethod.invoke(source);
        writeMethod.invoke(dest, val);
    }
}

并且我将此复制方法称为类似这样

 Utility.copy(user,userRequest);

并在执行 writeMethod.invoke(dest, val) 时出现以下异常。有人可以帮忙吗？

object is not an instance of declaring class at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:564)

Answer 1

您只会获得来源 class 的 BeanInfo，然后从 [=10] 获得属性描述符=]...所以 writeMethod 是 source class 上的 setter，但你在 [=] 的实例上调用它18=]目的地class.

您可能需要分别获取源和目标 class 的 BeanInfo，然后对于源中的每个属性，找到具有相同名称的那个（如果any) 在目标 class 中，并使用 that 属性的 write 方法来设置值。

Java 反思：对象不是声明的实例 class

Java Reflection: object is not an instance of declaring class

java

reflection