7.验证器

输入验证是Spring处理的最重要的Web开发任务之一

验证器属于Object级，它决定某一个对象中的所有field是否均是有效的，以及是否遵循某些规则

1.Spring的验证器

要实现org.springframework.validation.Validator接口

1 public interface Validator{
2      boolean supports(Class<?> clazz);
3      void validate(Object target,Errors errors);   
4 }

如果验证器可以处理指定的Class，supports方法将返回true，

validate方法会验证目标对象，并将验证错误填入Errors对象

给Errors对象添加错误的最容易方法是

调用reject，往FieldError中添加一个ObjectError和rejectError

只给reject或者rejectValue传入一个错误码，Spring就会在属性文件中查找错误码，

获得相应的信息

2.ValidateUtils类

org.springframework.validation.ValidationUtils类是一个工具类

有助于编写Spring验证器，

不需要

1 if(firstName==null || firstName.isEmpty()){
2      errors.rejectValue("price");   
3 }
4 
5 可以用
6 ValidateUtils.rejectIfEmpty("price");

3.Spring的Validate范例

 1 package app07a.domain;
 2 import java.io.Serializable;
 3 import java.util.Date;
 4 
 5 public class Product implements Serializable {
 6     private static final long serialVersionUID = 748392348L;
 7     private String name;
 8     private String description;
 9     private Float price;
10     private Date productionDate;
11 
12     public String getName() {
13         return name;
14     }
15     public void setName(String name) {
16         this.name = name;
17     }
18     public String getDescription() {
19         return description;
20     }
21     public void setDescription(String description) {
22         this.description = description;
23     }
24     public Float getPrice() {
25         return price;
26     }
27     public void setPrice(Float price) {
28         this.price = price;
29     }
30     public Date getProductionDate() {
31         return productionDate;
32     }
33     public void setProductionDate(Date productionDate) {
34         this.productionDate = productionDate;
35     }
36     
37 }

 1 package app07a.validator;
 2 
 3 import java.util.Date;
 4 
 5 import org.springframework.validation.Errors;
 6 import org.springframework.validation.ValidationUtils;
 7 import org.springframework.validation.Validator;
 8 
 9 import app07a.domain.Product;
10 
11 public class ProductValidator implements Validator {
12 
13     @Override
14     public boolean supports(Class<?> klass) {
15         return Product.class.isAssignableFrom(klass);
16     }
17 
18     @Override
19     public void validate(Object target, Errors errors) {
20         Product product = (Product) target;
21         ValidationUtils.rejectIfEmpty(errors, "name", "productname.required");
22         ValidationUtils.rejectIfEmpty(errors, "price", "price.required");
23         ValidationUtils.rejectIfEmpty(errors, "productionDate", "productiondate.required");
24         
25         Float price = product.getPrice();
26         if (price != null && price < 0) {
27             errors.rejectValue("price", "price.negative");
28         }
29         Date productionDate = product.getProductionDate();
30         if (productionDate != null) {
31             // The hour,minute,second components of productionDate are 0
32             if (productionDate.after(new Date())) {
33                 System.out.println("salah lagi");
34                 errors.rejectValue("productionDate", "productiondate.invalid");
35             }
36         }
37     }
38 }

验证器不需要显示注册，但是如果想要某个属性文件中获取错误消息，

则需要通过声明messageSource bean，告诉Spring去哪找这个文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
 4     xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
 5     xsi:schemaLocation="
 6         http://www.springframework.org/schema/beans
 7         http://www.springframework.org/schema/beans/spring-beans.xsd
 8         http://www.springframework.org/schema/mvc
 9         http://www.springframework.org/schema/mvc/spring-mvc.xsd     
10         http://www.springframework.org/schema/context
11         http://www.springframework.org/schema/context/spring-context.xsd">
12 
13     <context:component-scan base-package="app07a.controller" />
14     <context:component-scan base-package="app07a.formatter" />
15 
16     <mvc:annotation-driven conversion-service="conversionService" />
17 
18     <mvc:resources mapping="/css/**" location="/css/" />
19     <mvc:resources mapping="/*.html" location="/" />
20 
21     <bean id="viewResolver"
22         class="org.springframework.web.servlet.view.InternalResourceViewResolver">
23         <property name="prefix" value="/WEB-INF/jsp/" />
24         <property name="suffix" value=".jsp" />
25     </bean>
26     
27     <bean id="messageSource" 
28             class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
29         <property name="basename" value="/WEB-INF/resource/messages" />
30     </bean>
31     
32     <bean id="conversionService"
33         class="org.springframework.format.support.FormattingConversionServiceFactoryBean">
34         <property name="formatters">
35             <set>
36                 <bean class="app07a.formatter.DateFormatter">
37                     <constructor-arg type="java.lang.String" value="MM-dd-yyyy" />
38                 </bean>
39             </set>
40         </property>
41     </bean>
42 </beans>

message.properties文件

1 productname.required.product.name=Please enter a product name
2 price.required=Please enter a price
3 productiondate.required=Please enter a production date
4 productiondate.invalid=Invalid production date. Please ensure the production date is not later than today.

Controller

 1 package app07a.controller;
 2 
 3 import org.apache.commons.logging.Log;
 4 import org.apache.commons.logging.LogFactory;
 5 import org.springframework.stereotype.Controller;
 6 import org.springframework.ui.Model;
 7 import org.springframework.validation.BindingResult;
 8 import org.springframework.validation.FieldError;
 9 import org.springframework.web.bind.annotation.ModelAttribute;
10 import org.springframework.web.bind.annotation.RequestMapping;
11 
12 import app07a.domain.Product;
13 import app07a.validator.ProductValidator;
14 
15 @Controller
16 public class ProductController {
17 
18     private static final Log logger = LogFactory
19             .getLog(ProductController.class);
20 
21     @RequestMapping(value = "/product_input")
22     public String inputProduct(Model model) {
23         model.addAttribute("product", new Product());
24         return "ProductForm";
25     }
26 
27     @RequestMapping(value = "/product_save")
28     public String saveProduct(@ModelAttribute Product product,
29             BindingResult bindingResult, Model model) {
30         logger.info("product_save");
31         System.out.println("prod save");
32         ProductValidator productValidator = new ProductValidator();
33         productValidator.validate(product, bindingResult);
34 
35         if (bindingResult.hasErrors()) {
36             FieldError fieldError = bindingResult.getFieldError();
37             logger.info("Code:" + fieldError.getCode() + ", field:"
38                     + fieldError.getField());
39 
40             return "ProductForm";
41         }
42 
43         // save product here
44 
45         model.addAttribute("product", product);
46         return "ProductDetails";
47     }
48 }

测试验证器

http://localhost:8080/app07a/product_input