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标题: JSR 303 - Bean Validation 介绍及最佳实践 -3 [打印本页]

作者: look_w 时间: 2018-2-21 14:25 标题: JSR 303 - Bean Validation 介绍及最佳实践 -3

清单 6. @Status 的 constraint validator 部分

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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;
}
}

Bean Validation API 使用示例创建订单用户在创建一条订单记录时，需要填写以下信息：订单编号，客户，电子信箱，地址，状态，产品名称，产品价格
图 3. 创建订单

对这些信息的校验，使用 Bean Validation API
清单 7. 代码片段

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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");
}
}

如果用户不填写任何信息提交订单，相应的错误信息将会显示在页面上
图 4. 验证后返回错误信息

其实在整个程序的任何地方都可以调用 JSR 303 API 去对数据进行校验，然后将校验后的结果返回。
清单 8. 调用 JSR 303 API 进行校验

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

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