登录DTO在Spring Controller中不起作用[重复]

Question

这个问题在这里已有答案：

• What is the difference between == and equals() in Java? 23回答

我正在春季启动时登录休息。所以我创建了User实体和UserLoginDTO登录。但似乎它在运行时不起作用

我的DTO具有validation()功能，用于验证用户名和密码。但它很简单：

public boolean validate(String username, String password) {

        if (username == this.username && password == this.password) {
            return true;
        }
        return false;
    }

UserLoginDTO：

@Data
public class UserLoginDTO {
    private String username;
    private String password;

    public boolean validate(String username, String password) {

        if (username == this.username && password == this.password) {
            return true;
        }
        return false;
    }
}

用户：

@Entity
@Table(name = "users")
@Data
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "username", nullable = false, unique = true)
    private String username;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "joined_date", nullable = false, unique = true)
    @CreatedDate
    private Date joinedDate;

    @Column(name = "password")
    private String password;

    @Column(name = "bio")
    private String bio;

    @Column(name = "email", nullable = false, unique = true)
    private String email;
}   

@GetMapping("/login")
    public @ResponseBody String login(@RequestParam("username") String username, @RequestParam("password") String password) {

        User user = repo.queryUserLogin(username, password);
        UserLoginDTO dto = new UserLoginDTO();

        dto.setUsername(user.getUsername());
        dto.setPassword(user.getPassword());

        if(dto.validate(username, password)) {
            return "Login successfully!";
        }

        return "Login failed!";
    }

但是当我运行代码并尝试从URL获取结果时（我使用postman）。但这不能正常工作：

Answer 1

您应该使用equals方法比较字符串，而不是使用==

你可以在这里读到它https://javarevisited.blogspot.com/2012/12/difference-between-equals-method-and-equality-operator-java.html