Java Spring JPA、延迟初始化和Dto_Java_Hibernate_Jpa_Dto

Java Spring JPA、延迟初始化和Dto

java hibernate jpa

Java Spring JPA、延迟初始化和Dto,java,hibernate,jpa,dto,Java,Hibernate,Jpa,Dto,我试图在登录后（从登录成功过滤器）获取用户的配置文件数据，但我发现延迟加载数据的异常。请参见以下示例代码： AuthenticationSuccessHandler.java @Component public class AuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler { @Autowired private UserService userService;

我试图在登录后（从登录成功过滤器）获取用户的配置文件数据，但我发现延迟加载数据的异常。请参见以下示例代码：

AuthenticationSuccessHandler.java

@Component
public class AuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {

    @Autowired
    private UserService userService;

    @Autowired
    private Gson gson;

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) throws ServletException, IOException {

        User user = (User) authentication.getPrincipal();
        UserLoginResponseDto userLoginResponseDto = userService.login(user.getUsername());

        response.setStatus(HttpStatus.OK.value());
        response.setContentType("application/json; charset=UTF-8");
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        response.getWriter().println(gson.toJson(userLoginResponseDto));
        response.getWriter().flush();

        clearAuthenticationAttributes(request);
    }
}

public class UserService implements UserDetailsService, TokenService {

    @Autowired
    private UserRepository userRepository;

    @Transactional(readOnly = true)
    public UserLoginResponseDto login(String email) {
        Optional<UserModel> userOptional = userRepository.findByEmailIgnoreCase(email);
        UserModel userModel = userOptional.get();
        UserLoginResponseDto userLoginResponseDto = userModel.toUserLoginResponseDto();
        return userLoginResponseDto;
    }
}

public class UserModel {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true, updatable = false)
    private UUID id;


    [A FEW MORE FIELDS]

    @Column(length = 256, nullable = false, unique = true, updatable = false)
    private String email;

    @OneToMany(cascade = { CascadeType.ALL })
    private List<RoleModel> roleModels;

    public UserLoginResponseDto toUserLoginResponseDto() {
        return new UserLoginResponseDto().setId(id).setEmail(email).setRoles(roleModels);
    }
}

public class UserLoginResponseDto {

    private UUID id;
    private String email;
    private List<RoleModel> roles;

}

UserService.java

@Component
public class AuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {

    @Autowired
    private UserService userService;

    @Autowired
    private Gson gson;

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) throws ServletException, IOException {

        User user = (User) authentication.getPrincipal();
        UserLoginResponseDto userLoginResponseDto = userService.login(user.getUsername());

        response.setStatus(HttpStatus.OK.value());
        response.setContentType("application/json; charset=UTF-8");
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        response.getWriter().println(gson.toJson(userLoginResponseDto));
        response.getWriter().flush();

        clearAuthenticationAttributes(request);
    }
}

public class UserService implements UserDetailsService, TokenService {

    @Autowired
    private UserRepository userRepository;

    @Transactional(readOnly = true)
    public UserLoginResponseDto login(String email) {
        Optional<UserModel> userOptional = userRepository.findByEmailIgnoreCase(email);
        UserModel userModel = userOptional.get();
        UserLoginResponseDto userLoginResponseDto = userModel.toUserLoginResponseDto();
        return userLoginResponseDto;
    }
}

public class UserModel {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true, updatable = false)
    private UUID id;


    [A FEW MORE FIELDS]

    @Column(length = 256, nullable = false, unique = true, updatable = false)
    private String email;

    @OneToMany(cascade = { CascadeType.ALL })
    private List<RoleModel> roleModels;

    public UserLoginResponseDto toUserLoginResponseDto() {
        return new UserLoginResponseDto().setId(id).setEmail(email).setRoles(roleModels);
    }
}

public class UserLoginResponseDto {

    private UUID id;
    private String email;
    private List<RoleModel> roles;

}

public类UserService实现userdetails服务，TokenService{
@自动连线
私有用户存储库用户存储库；
@事务（只读=真）
公共用户登录响应登录（字符串电子邮件）{
Optional userOptional=userRepository.findByEmailIgnoreCase（电子邮件）；
UserModel UserModel=userOptional.get（）；
UserLoginResponseTo UserLoginResponseTo=userModel.ToUserLoginResponseTo（）；
返回userLoginResponseDto；
}
}

UserModel.java

@Component
public class AuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {

    @Autowired
    private UserService userService;

    @Autowired
    private Gson gson;

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) throws ServletException, IOException {

        User user = (User) authentication.getPrincipal();
        UserLoginResponseDto userLoginResponseDto = userService.login(user.getUsername());

        response.setStatus(HttpStatus.OK.value());
        response.setContentType("application/json; charset=UTF-8");
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        response.getWriter().println(gson.toJson(userLoginResponseDto));
        response.getWriter().flush();

        clearAuthenticationAttributes(request);
    }
}

public class UserService implements UserDetailsService, TokenService {

    @Autowired
    private UserRepository userRepository;

    @Transactional(readOnly = true)
    public UserLoginResponseDto login(String email) {
        Optional<UserModel> userOptional = userRepository.findByEmailIgnoreCase(email);
        UserModel userModel = userOptional.get();
        UserLoginResponseDto userLoginResponseDto = userModel.toUserLoginResponseDto();
        return userLoginResponseDto;
    }
}

public class UserModel {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true, updatable = false)
    private UUID id;


    [A FEW MORE FIELDS]

    @Column(length = 256, nullable = false, unique = true, updatable = false)
    private String email;

    @OneToMany(cascade = { CascadeType.ALL })
    private List<RoleModel> roleModels;

    public UserLoginResponseDto toUserLoginResponseDto() {
        return new UserLoginResponseDto().setId(id).setEmail(email).setRoles(roleModels);
    }
}

public class UserLoginResponseDto {

    private UUID id;
    private String email;
    private List<RoleModel> roles;

}

公共类用户模型{
@身份证
@GeneratedValue（策略=GenerationType.AUTO）
@列（nullable=false，unique=true，Updateable=false）
私有UUID；
[还有几个字段]
@列（长度=256，可空=false，唯一=true，可更新=false）
私人字符串电子邮件；
@OneToMany（cascade={CascadeType.ALL}）
私有列表角色模型；
公共用户登录回复TouserLoginResponseTo（）{
返回新的UserLoginResponseDto（）.setId（id）.setEmail（email）.setRoles（roleModels）；
}
}

UserLoginResponseDto.java

@Component
public class AuthenticationSuccessHandler extends SavedRequestAwareAuthenticationSuccessHandler {

    @Autowired
    private UserService userService;

    @Autowired
    private Gson gson;

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
            Authentication authentication) throws ServletException, IOException {

        User user = (User) authentication.getPrincipal();
        UserLoginResponseDto userLoginResponseDto = userService.login(user.getUsername());

        response.setStatus(HttpStatus.OK.value());
        response.setContentType("application/json; charset=UTF-8");
        response.setCharacterEncoding(StandardCharsets.UTF_8.name());
        response.getWriter().println(gson.toJson(userLoginResponseDto));
        response.getWriter().flush();

        clearAuthenticationAttributes(request);
    }
}

public class UserService implements UserDetailsService, TokenService {

    @Autowired
    private UserRepository userRepository;

    @Transactional(readOnly = true)
    public UserLoginResponseDto login(String email) {
        Optional<UserModel> userOptional = userRepository.findByEmailIgnoreCase(email);
        UserModel userModel = userOptional.get();
        UserLoginResponseDto userLoginResponseDto = userModel.toUserLoginResponseDto();
        return userLoginResponseDto;
    }
}

public class UserModel {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true, updatable = false)
    private UUID id;


    [A FEW MORE FIELDS]

    @Column(length = 256, nullable = false, unique = true, updatable = false)
    private String email;

    @OneToMany(cascade = { CascadeType.ALL })
    private List<RoleModel> roleModels;

    public UserLoginResponseDto toUserLoginResponseDto() {
        return new UserLoginResponseDto().setId(id).setEmail(email).setRoles(roleModels);
    }
}

public class UserLoginResponseDto {

    private UUID id;
    private String email;
    private List<RoleModel> roles;

}

public类用户登录回复到{
私有UUID；
私人字符串电子邮件；
私有列表角色；
}

当在

AuthenticationSuccessHandler

中序列化UserLoginResponseDto类型的对象时，我会看到以下错误消息-

org.hibernate.LazyInitializationException:未能延迟初始化角色集合：UserModel.roleModels，无法初始化代理-无会话

QQ-如何在不使用以下任何技术的情况下正确解决此问题

[反模式]在视图中打开
[反模式]hibernate.enable\u lazy\u load\u no\u trans
FetchType.EAGER

您的问题是将实际的惰性

列表

传递到

设置角色

，这不会触发满负载。这表明（立即）虽然您已将顶级数据库类与顶级DTO分离，但这是一种“浅”分离，不能完全实现值。您还没有说明

RoleModel

是实体还是可嵌入的，这很重要

因此，第一步是将项目复制到非JPA表单中。如果

RoleModel

embedded（本质上是一个POJO），这可以像

setRoles（新的ArrayList（roles））

一样简单。否则，您需要一个嵌套的DTO，此时可能会考虑一些类似于MaSpult.

的东西。

但是，无论哪种情况，您都可能遇到N+1问题。事实上，在这种情况下，您确实需要一个急切的获取，这就是JPA实体图的用途。您可以告诉Spring Data只在您需要的时候才急切地获取列表，这是一个完美的例子，说明了何时进行此操作。

RoleModel

是一个实体，我们可以从这个映射中看到：

@OneToMany（cascade={CascadeType.ALL}）private list roleModels