如何有效地比较同一类的两个对象并检查哪些字段不同？

Question

我想写一个泛型函数，接受同一实体类的两个对象，比较不同的字段，并返回对特定字段所做的所有更改的列表。

public class Member {
    String firstName;
    String lastName;
    String driverLicenseNumber;
    Integer age;
    LocalDateTime timestamp;
}

public class MemberAuditsResource {
    private String field;
    private LocalDateTime on;
    private String changeType;
    private String oldValue;
    private String newValue;
}

private List<MembeAuditsResource> memberCompare(Member obj1, Member obj2) {

    //Compare every field in both the objects using if else and populate the resource.

}

然后调用上面的函数比较entity_audit表中的每一对记录。代码将非常大，以比较每个字段，并乘以不同的实体。有没有更好更高效的办法？

Answer 1

如果你扩展思想来比较对象图，这不是一个琐碎的问题。因此，有效的方法不是重新发明轮子，而是使用现有的库，如JaVers：

Member oldMember = new Member("foo" ,"chan" ,"AB12" , 21 ,LocalDateTime.now());
Member newMember = new Member("bar" ,"chan" ,"AB12" , 22 ,LocalDateTime.now());

Diff diff = javers.compare(oldMember, newMember);
for(Change change:  diff.getChanges()) {
    System.out.println(change);
}

然后，可以得到如下内容：

ValueChange{ 'firstName' changed from 'foo' to 'bar' }
ValueChange{ 'age' changed from '21' to '22' }