spring mvc 使用jsr-303进行表单验证的方法介绍
源代码来源：http://howtodoinjava.com/spring/spring-mvc/spring-bean-validation-example-with-jsr-303-annotations/，原文解释的更加清楚。此文主要是为了理顺整个项目的构建过程。
采用JSR303来进行FORM验证，JSR-303实体验证的主要目的是通过注解对JAVA实体进行标准化验证。其主要目标是直接在java实体类中使用注解。即通过注释将需要验证的代码直接使用相应的验证规则进行验证，这样则不需要重新建立验证规则的类型。其中主要是使用了JSR-303标准。
首先先看下项目的结构。
首先，创建maven项目，然后修改其结构发布到tomcat服务器中。
2.通过maven，引入需要的jar包，pom.xml文件如下：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.howtodoinjava.mvc</groupId>
<artifactId>jsr303Demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>1.0.0.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>4.3.1.Final</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!-- Spring MVC support -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
<!-- Tag libs support for view layer -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
<scope>runtime</scope>
</dependency>
</dependencies>
</project>
3. 在model中添加验证准则
package com.howtodoinjava.demo.model;
import java.io.Serializable;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
public class EmployeeVO implements Serializable
{
private static final long serialVersionUID = 1L;
private Integer id;
@Size(min = 3, max = 20)
private String firstName;
@Size(min = 3, max = 20)
private String lastName;
@Pattern(regexp=".+@.+\\.[a-z]+")
private String email;
//Setters and Getters
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "EmployeeVO [id=" + id + ", firstName=" + firstName
+ ", lastName=" + lastName + ", email=" + email + "]";
}
}
4.配置web.xml以及spring-servlet.xml文件（spring调度器）
--- web.xml文件
<web-app id="WebApp_ID" version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>Spring Web MVC Hello World Application</display-name>
<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>spring</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
--- spring-servlet.xml文件
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:component-scan base-package="com.howtodoinjava.demo" />
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
<bean class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basename" value="messages" />
</bean>
</beans>
红色部分为通过配置文件配置解析器（disolver）。所以需要在WEB-INF文件下建立messages.properties文件，spring会自动去识别messages开头的文件。其内容如下：
lbl.page=Add New Employee
lbl.firstName=First Name
lbl.lastName=Last Name
lbl.email=Email Id
5. 编写controller，创建EmployeeController.class，具体代码如下:
package com.howtodoinjava.demo.controller;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.bind.support.SessionStatus;
import com.howtodoinjava.demo.model.EmployeeVO;
import com.howtodoinjava.demo.service.EmployeeManager;
@Controller
@RequestMapping("/employee-module/addNew")
@SessionAttributes("employee")
public class EmployeeController {
@Autowired
EmployeeManager manager;
private Validator validator;
public EmployeeController()
{
ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
validator = validatorFactory.getValidator();
}
@RequestMapping(method = RequestMethod.GET)
public String setupForm(Model model) {
EmployeeVO employeeVO = new EmployeeVO();
model.addAttribute("employee", employeeVO);
return "addEmployee";
}
@RequestMapping(method = RequestMethod.POST)
public String submitForm(@ModelAttribute("employee") EmployeeVO employeeVO,
BindingResult result, SessionStatus status) {
Set<ConstraintViolation<EmployeeVO>> violations = validator.validate(employeeVO);
for (ConstraintViolation<EmployeeVO> violation : violations)
{
String propertyPath = violation.getPropertyPath().toString();
String message = violation.getMessage();
// Add JSR-303 errors to BindingResult
// This allows Spring to display them in view via a FieldError
result.addError(new FieldError("employee",propertyPath,
"Invalid "+ propertyPath + "(" + message + ")"));
}
if (result.hasErrors()) {
return "addEmployee";
}
// Store the employee information in database
// manager.createNewRecord(employeeVO);
// Mark Session Complete
status.setComplete();
return "redirect:addNew/success";
}
@RequestMapping(value = "/success", method = RequestMethod.GET)
public String success(Model model) {
return "addSuccess";
}
}
5.创建view，一个addEmployee.jsp和一个addSuccess.jsp，分别如下：
--- addEmployee.jsp文件
<%@ page contentType="text/html;charset=UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>
<html>
<head>
<title>Add Employee Form</title>
</head>
<body>
<h2><spring:message code="lbl.page" text="Add New Employee" /></h2>
<br/>
<form:form method="post" modelAttribute="employee">
<table>
<tr>
<td><spring:message code="lbl.firstName" text="First Name" /></td>
<td><form:input path="firstName" /></td>
<td><form:errors path="firstName" cssClass="error" /></td>
</tr>
<tr>
<td><spring:message code="lbl.lastName" text="Last Name" /></td>
<td><form:input path="lastName" /></td>
<td><form:errors path="lastName" cssClass="error" /></td>
</tr>
<tr>
<td><spring:message code="lbl.email" text="Email Id" /></td>
<td><form:input path="email" /></td>
<td><form:errors path="email" cssClass="error" /></td>
</tr>
<tr>
<td colspan="3"><input type="submit" value="Add Employee"/></td>
</tr>
</table>
</form:form>
</body>
</html>
--- addSuccess.jsp文件
<html>
<head>
<title>Add Employee Success</title>
</head>
<body>
Employee has been added successfully.
</body>
</html>
到此使用JSR-303验证表单数据的例子就结束了。通过url = http://localhost:8080/jsr303Demo/employee-module/addNew进行访问，则
点击Add Employee按钮，当输入数据不符合验证规则时，则会显示错误信息。
