【Java.Web】MVC —— Action的验证器 —— Validator
验证器 —— Validator
在执行Action时，输入验证时一个重要的步骤。验证范围从简单的任务到复杂的任务都有，例如简单的有检验某个输入域中是否有值，复杂的有验证信用卡号码等。
Java社区发布了 JSR 303 "Bean Validation"，将Java中的输入验证标准化。
现代的MVC框架经常同时提供编程式和声明式的验证方法。
示例
基于 MVC - 基于Filter Dispatcherr的Model2 - 示例 一节：
添加如下的Validator - ProductValidator.java
package com.gof.test.validator;
import java.util.List;
import java.util.ArrayList;
import com.gof.test.bean.ProductForm;
import com.sun.tools.javah.LLNI;
public class ProductValidator {
public List<String> validate(ProductForm productForm){
List<String> errors = new ArrayList<String>();
String name = productForm.getName();
if (name == null || name.trim().isEmpty()){
errors.add("Product must have a name");
}
String price = productForm.getPrice();
if (price == null || price.trim().isEmpty()){
errors.add("Price must have a price");
}else{
try{
Float.parseFloat(price);
}catch (NumberFormatException e){
errors.add("Invalid price value");
}
}
return errors;
}
}
修改上一个的Filter为：
package com.gof.test.filter;
import java.io.IOException;
import java.util.List;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.gof.test.action.SaveProductAction;
import com.gof.test.bean.Product;
import com.gof.test.bean.ProductForm;
import com.gof.test.validator.ProductValidator;
public class DispatcherFilter implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
// TODO Auto-generated method stub
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
String uri = ((HttpServletRequest)req).getRequestURI();
int lastIndex = uri.lastIndexOf("/");
String action = uri.substring(lastIndex + 1);
String dispatchUrlString = null;
if (action.equals("product_input")){
dispatchUrlString = "/jsp/controller/ProductForm.jsp";
}else
if (action.equals("product_save")){
ProductForm productForm = new ProductForm();
productForm.setName(req.getParameter("name"));
productForm.setDescription(req.getParameter("description"));
productForm.setPrice(req.getParameter("price"));
// begin validate
ProductValidator productValidator = new ProductValidator();
List<String> errors = productValidator.validate(productForm);
// end validate
if (errors.isEmpty()){
Product product = new Product();
product.setName(productForm.getName());
product.setDescription(productForm.getDescription());
product.setPrice(Float.parseFloat(productForm.getPrice()));
SaveProductAction saveProductAction = new SaveProductAction();
saveProductAction.save(product);
req.setAttribute("product", product);
dispatchUrlString = "/jsp/controller/ProductDetails.jsp";
}else{
req.setAttribute("errors", errors);
req.setAttribute("form", productForm);
dispatchUrlString = "/jsp/controller/ProductForm.jsp";
}
}
if (dispatchUrlString != null){
RequestDispatcher rDispatcher = req.getRequestDispatcher(dispatchUrlString);
rDispatcher.forward(req, resp);
}else{
chain.doFilter(req, resp);
}
}
public void destroy() {
// TODO Auto-generated method stub
}
}
修改 ProductForm.jsp如下：
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Add Product Form</title>
</head>
<body>
<div>
<h3>Add a product</h3>
<c:if test="${requestScope.errors != null}">
<p>
<ul>
<c:forEach var="error" items="${requestScope.errors}">
<li>${error}</li>
</c:forEach>
</ul>
</p>
</c:if>
<form method="post" action="product_save">
<table>
<tr>
<td>Product Name:</td>
<td><input type="text" name="name" value="${form.name}"/></td>
</tr>
<tr>
<td>Description:</td>
<td><input type="text" name="description" value="${form.description}"/></td>
</tr>
<tr>
<td>Price:</td>
<td><input type="text" name="price" value="${form.price}"/></td>
</tr>
<tr>
<td><input type="reset" /></td>
<td><input type="submit" value="Add Product"/></td>
</tr>
</table>
</form>
</div>
</body>
</html>
访问如下URL:
http://localhost:8080/base-webapp/product_input
输入错误信息，提交：
