Spring MVC学习笔记——JSR303介绍及最佳实践

 public class Order {
 // 必须不为 null, 大小是 10
 @NotNull
 @Size(min = 10, max = 10)
 private String orderId;
 // 必须不为空
 @NotEmpty
 private String customer;
 // 必须是一个电子信箱地址
 @Email
 private String email;
 // 必须不为空
 @NotEmpty
 private String address;
 // 必须不为 null, 必须是下面四个字符串‘created‘, ‘paid‘, ‘shipped‘, ‘closed‘其中之一
 // @Status 是一个定制化的 contraint
 @NotNull
 @Status
 private String status;
 // 必须不为 null
 @NotNull
 private Date createDate;
 // 嵌套验证
 @Valid
 private Product product; 

…
 getter 和 setter
 }

 public class Product {
 // 必须非空
 @NotEmpty
 private String productName;
 // 必须在 8000 至 10000 的范围内
 // @Price 是一个定制化的 constraint
 @Price
 private float price;
…
 Getter 和 setter
 }
			

 // ‘to‘所表示的日期必须在‘from‘所表示的日期之后
 // @QueryConstraint 是一个定制化的 constraint
 @QueryConstraint
 public class OrderQuery {
 private Date from;
 private Date to;
… omitted …
 Getter and setter
 }

 // @Max 和 @Min 都是内置的 constraint
 @Max(10000)
 @Min(8000)
 @Constraint(validatedBy = {})
 @Documented
 @Target( { ElementType.ANNOTATION_TYPE, ElementType.METHOD, ElementType.FIELD })
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Price {
 String message() default "错误的价格";
 Class<?>[] groups() default {};
 Class<? extends Payload>[] payload() default {};
 }

 @Constraint(validatedBy = {StatusValidator.class})
 @Documented
 @Target( { ElementType.ANNOTATION_TYPE, ElementType.METHOD, ElementType.FIELD })
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Status {
 String message() default "不正确的状态 , 应该是 ‘created‘, ‘paid‘, shipped‘, closed‘其中之一";
 Class<?>[] groups() default {};
 Class<? extends Payload>[] payload() default {};
 }

 public class StatusValidator implements ConstraintValidator<Status, String>{
 private final String[] ALL_STATUS = {"created", "paid", "shipped", "closed"};
 public void initialize(Status status) {
 }
 public boolean isValid(String value, ConstraintValidatorContext context) {
 if(Arrays.asList(ALL_STATUS).contains(value))
 return true;
 return false;
 }
 }

 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
 throws ServletException, IOException {
 HttpSession session = req.getSession();
 // 从 request 中获取输入信息
 String orderId = (String) req.getParameter("orderId");
 String customer = (String) req.getParameter("customer");
 String email = (String) req.getParameter("email");
 String address = (String) req.getParameter("address");
 String status = (String) req.getParameter("status");
 String productName = (String) req.getParameter("productName");
 String productPrice = (String) req.getParameter("productPrice");
 // 将 Bean 放入 session 中
 Order order = new Order();
 order.setOrderId(orderId);
 order.setCustomer(customer);
 order.setEmail(email);
 order.setAddress(address);
 order.setStatus(status);
 order.setCreateDate(new Date());
 Product product = new Product();
 product.setName(productName);
 if(productPrice != null && productPrice.length() > 0)
 product.setPrice(Float.valueOf(productPrice));
 order.setProduct(product);
 session.setAttribute("order", order);
 ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
 Validator validator = factory.getValidator();
 Set<ConstraintViolation<Order>> violations = validator.validate(order);
 if(violations.size() == 0) {
 session.setAttribute("order", null);
 session.setAttribute("errorMsg", null);
 resp.sendRedirect("creatSuccessful.jsp");
 } else {
 StringBuffer buf = new StringBuffer();
 ResourceBundle bundle = ResourceBundle.getBundle("messages");
 for(ConstraintViolation<Order> violation: violations) {
 buf.append("-" + bundle.getString(violation.getPropertyPath().toString()));
 buf.append(violation.getMessage() + "<BR>\n");
 }
 session.setAttribute("errorMsg", buf.toString());
 resp.sendRedirect("createOrder.jsp");
 }
 }

 Order order = new Order();
…
 ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
 Validator validator = factory.getValidator();
 Set<ConstraintViolation<Order>> violations = validator.validate(order);