java - 如何在 spring mvc 应用程序中向数据库添加重复用户名时处理异常

Question

我正在构建 spring mvc 应用程序。我想禁止添加重复(用户名是主键)条目并通知以选择另一个用户名。

我正在研究注册用户选项。一切正常，直到我将用户与已经存在的用户名放在一起。好吧，这是故意的，因为用户名列是我数据库中的主键。

我正在寻找一个选项来处理这个:

这是我的 SQL 表

 create table users(
  username varchar(50) not null primary key,
  password varchar(50) not null);

这是我的仓库:

@Repository

class UserRepositoryImpl implements UserRepository{

    @Autowired
    private JdbcTemplate jdbcTemplate;


    @Override
    public void addUser(User user) throws MySQLIntegrityConstraintViolationException {
        /*language=SQL*/
        String SQL_ADD_USER= "INSERT INTO users VALUES (?,?)";

        String username  = user.getUsername();
        String password  = user.getPassword();
        jdbcTemplate.update(SQL_ADD_USER, username, password);

    }
}

这是我的 Controller 类的一部分:

@RequestMapping(value="/register", method = RequestMethod.GET)
public String registerPage(@ModelAttribute("user") User user){return "register";}

@RequestMapping(value="/register", method=RequestMethod.POST)
public String processRegisterUser(@ModelAttribute("user") User user, BindingResult result){

    try {
        userRepository.addUser(user);
    } catch (com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException e) {

        //some line of code that would add information to the view that user with given username already exists.
    }


    return "redirect:/login";
}

如您所见，我尝试处理在添加重复条目期间发生的异常。这就是为什么我将此子句 throws MySQLIntegrityConstraintViolationException 放在 public void addUser(User user) 中。在下一步中，我想在 public String processRegisterUser 方法中处理这个异常，这样我就可以通知用户给定的用户名已被占用。嗯，这是行不通的。我无法处理 com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException 并且在 View 中添加重复错误而不是警告时我得到:

 HTTP Status 500 - Request processing failed; nested exception is org.springframework.dao.DuplicateKeyException: PreparedStatementCallback; SQL [INSERT INTO users VALUES (?,?)]; Duplicate entry 'user' for key 'PRIMARY'; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry 'user' for key 'PRIMARY'

type Exception report

message Request processing failed; nested exception is org.springframework.dao.DuplicateKeyException: PreparedStatementCallback; SQL [INSERT INTO users VALUES (?,?)]; Duplicate entry 'user' for key 'PRIMARY'; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry 'user' for key 'PRIMARY'

description The server encountered an internal error that prevented it from fulfilling this request.

exception

    org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.DuplicateKeyException: PreparedStatementCallback; SQL [INSERT INTO users VALUES (?,?)]; Duplicate entry 'user' for key 'PRIMARY'; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry 'user' for key 'PRIMARY'
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
        org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:317)
        org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
        org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
        org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
        org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:115)
        org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
        org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)

如果您需要任何详细信息，请发表评论。

Answer 1

你正在使用 spring jdbcTemplate 进行数据库连接，它有自己的异常层次结构，所以你可以 try catch spring 异常 org.springframework.dao.DuplicateKeyException