数据校验是每个项⽬中必不可少的模块，Spring MVC 提供了两种数据校验的组件：
1.基于 Validator 接⼝进⾏校验
2.使⽤ Annotation JSR-303 标准校验
使⽤基于 Validator 接⼝进⾏校验会复杂⼀些，具体的数据校验的规则需要开发者⼿动设置。⽽使⽤ Annotation JSR-303 标准会相对简单⼀些，开发者不需要编写校验规则，直接通过注解的形式给每⼀条 数据添加验证规则，具体操作是直接在实体类的属性上添加对应的校验注解即可。
一、基于 Validator 接⼝
1.1 创建实体类
java
package com.southwind.entity;
import lombok.Data;
@Data
public class Student {
private String name;
private String password;
}1.2 ⾃定义数据校验器 StudentValidation，实现 Validator 接⼝，重写接⼝的抽象⽅法，加⼊校验规则。
java
package com.southwind.validation;
import com.southwind.entity.Student;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
public class StudentValidation implements Validator {
@Override
public boolean supports(Class<?> aClass) {
return Student.class.equals(aClass);
}
@Override
public void validate(Object o, Errors errors) {
ValidationUtils.rejectIfEmpty(errors, "name", null, "姓名不能为空");
ValidationUtils.rejectIfEmpty(errors, "password", null, "密码不能为空");
}
}1.3 控制层业务⽅法
java
package com.southwind.controller;
import com.southwind.entity.Student;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("/validate")
public class ValidateHandler {
/**
* 给JSP表单绑定模型对象
* @param model
* @return
*/
@GetMapping("/login")
public String login(Model model) {
model.addAttribute(new Student());
return "login";
}
/**
* 数据校验
* @param student
* @param bindingResult
* @return
*/
@PostMapping("/login")
public String login(@Validated Student student, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
return "login";
}
return "success";
}
}1.4 springmvc.xml 配置 validator
XML
<mvc:annotation-driven validator="studentValidator">
<!-- 启用基于注解的 MVC 功能，并指定验证器 -->
</mvc:annotation-driven>
<bean id="studentValidator" class="com.southwind.validation.StudentValidation">
<!-- 定义一个名为 studentValidator 的验证器 Bean -->
</bean>1.5 JSP
javascript
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>学⽣登陆</h1>
<form:form modelAttribute="student" action="/validate/login" method="post">
学⽣姓名: <form:input path="name" /> <form:errors path="name" /><br/>
学⽣密码: <form:input path="password" /> <form:errors path="password" /><br/>
<input type="submit" value="提交"/>
</form:form>
</body>
</html>二、Annotation JSR-303 标准
Hibernater Validator，通过注解完成校验规则的绑定。
@Null 只能为 null
@NotNull 不能为 null
@Size 设置数据⻓度
@NotEmpty 不能为空
String str = null;
String str = "";
2.1 pom.xml
XML
<!-- JSR-303 -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.3.6.Final</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging</artifactId>
<version>3.4.1.Final</version>
</dependency>
<!-- JDK9以上 -->
<dependency>
<groupId>javax.xml.bind</groupId>
<artifactId>jaxb-api</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>com.sun.xml.bind</groupId>
<artifactId>jaxb-impl</artifactId>
<version>2.3.0</version>
</dependency>
<dependency>
<groupId>com.sun.xml.bind</groupId>
<artifactId>jaxb-core</artifactId>
<version>2.3.0</version>
</dependency>
<dependency>
<groupId>javax.activation</groupId>
<artifactId>activation</artifactId>
<version>1.1.1</version>
</dependency>2.2 创建实体类，通过注解的⽅式给属性指定校验规则。
java
package com.southwind.entity;
import lombok.Data;
import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.NotEmpty;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
@Data
public class Account {
@NotEmpty(message = "⽤户名不能为空")
private String username;
@Size(min = 6, max = 20, message = "密码⻓度为6 - 20位")
private String password;
@Email(regexp = "^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+(\\\\.[a-zA-Z0-9-]+)*\\\\.[a-zA-Z0-9]{2,6}$", message = "请输⼊正确的邮箱")
private String email;
@Pattern(regexp = "^((13[0-9])|(14[5|7])|(15([0-3]|[5-9]))|(18[0,5-9]))\\\\d{8}$", message = "请输⼊正确的电话格式")
private String phone;
}2.3 业务⽅法
java
@GetMapping("/register")
public String register(Model model) {
model.addAttribute(new Account());
return "register";
}
@PostMapping("/register")
public String register(@Valid Account account, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
return "register";
}
return "success";
}2.4 springmvc.xml
XML
<mvc:annotation-driven></mvc:annotation-driven>2.5 register.jsp
javascript
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>⽤户注册</h1>
<form:form modelAttribute="account" action="/validate/register" method="post">
⽤户名：<form:input path="username"></form:input><form:errors path="username"></form:errors><br/>
密码：<form:input path="password"></form:input><form:errors path="password"></form:errors><br/>
邮箱：<form:input path="email"></form:input><form:errors path="email"></form:errors><br/>
电话：<form:input path="phone"></form:input><form:errors path="phone"></form:errors><br/>
<input type="submit" value="提交"/>
</form:form>
</body>
</html>