Javassm - SpringBoot3

@SpringBootTest
class SpringBootTestApplicationTests {

      //JavaMailSender是专门用于发送邮件的对象，自动配置类已经提供了Bean
    @Autowired
    JavaMailSender sender;

    @Test
    void contextLoads() {
          //SimpleMailMessage是一个比较简易的邮件封装，支持设置一些比较简单内容
        SimpleMailMessage message = new SimpleMailMessage();
          //设置邮件标题
        message.setSubject("【电子科技大学教务处】关于近期学校对您的处分决定");
          //设置邮件内容
        message.setText("XXX同学您好，经监控和教务巡查发现，您近期存在旷课、迟到、早退、上课刷抖音行为，" +
                "现已通知相关辅导员，请手写5000字书面检讨，并在2022年4月1日17点前交到辅导员办公室。");
          //设置邮件发送给谁，可以多个，这里就发给你的QQ邮箱
        message.setTo("你的QQ号@qq.com");
          //邮件发送者，这里要与配置文件中的保持一致
        message.setFrom("javastudy111@163.com");
          //OK，万事俱备只欠发送
        sender.send(message);
    }

}

@Test
void contextLoads() throws MessagingException {
      //创建一个MimeMessage
    MimeMessage message = sender.createMimeMessage();
      //使用MimeMessageHelper来帮我们修改MimeMessage中的信息
    MimeMessageHelper helper = new MimeMessageHelper(message, true);
    helper.setSubject("Test");
    helper.setText("lbwnb");
    helper.setTo("你的QQ号@qq.com");
    helper.setFrom("javastudy111@163.com");
      //发送修改好的MimeMessage
    sender.send(message);
}

@ResponseBody
@PostMapping("/submit")
public String submit(String username,
                     String password){
    System.out.println(username.substring(3));
    System.out.println(password.substring(2, 10));
    return "请求成功!";
}

@ResponseBody
@PostMapping("/submit")
public String submit(String username,
                     String password){
    if(username.length() > 3 && password.length() > 10) {
        System.out.println(username.substring(3));
        System.out.println(password.substring(2, 10));
        return "请求成功!";
    } else {
        return "请求失败";
    }
}

@Slf4j
@Validated   //首先在Controller上开启接口校验
@Controller
public class TestController {

    ...

    @ResponseBody
    @PostMapping("/submit")
    public String submit(@Length(min = 3) String username,  //使用@Length注解一步到位
                         @Length(min = 10) String password){
        System.out.println(username.substring(3));
        System.out.println(password.substring(2, 10));
        return "请求成功!";
    }
}

@ControllerAdvice
public class ValidationController {

    @ResponseBody
    @ExceptionHandler(ConstraintViolationException.class)
    public String error(ValidationException e){
        return e.getMessage();   //出现异常直接返回消息
    }
}

@Data
public class Account {
    String username;
    String password;
}

@ResponseBody
@PostMapping("/submit")
public String submit(Account account){   //直接使用对象接收
    System.out.println(account.getUsername().substring(3));
    System.out.println(account.getPassword().substring(2, 10));
    return "请求成功!";
}

@ResponseBody
@PostMapping("/submit")  //在参数上添加@Valid注解表示需要验证
public String submit(@Valid Account account){
    System.out.println(account.getUsername().substring(3));
    System.out.println(account.getPassword().substring(2, 10));
    return "请求成功!";
}

@Data
public class Account {
    @Length(min = 3)   //只需要在对应的字段上添加校验的注解即可
    String username;
    @Length(min = 10)
    String password;
}

@ResponseBody
@ExceptionHandler({ConstraintViolationException.class, MethodArgumentNotValidException.class})
public String error(Exception e){
    if(e instanceof ConstraintViolationException exception) {
        return exception.getMessage();
    } else if(e instanceof MethodArgumentNotValidException exception){
        if (exception.getFieldError() == null) return "未知错误";
        return exception.getFieldError().getDefaultMessage();
    }
    return "未知错误";
}