Spring MVC自定义验证

Spring MVC框架允许我们执行自定义验证。在这种情况下，我们声明自己的注解。我们可以根据自己的业务逻辑执行验证。

Spring MVC自定义验证示例

在此示例中，我们既使用预定义的注解，又使用自定义注解来验证用户输入。

1. 在pom.xml文件中添加依赖。

pom.xml

<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->  
<dependency>  
    <groupId>org.springframework</groupId>  
    <artifactId>spring-webmvc</artifactId>  
    <version>5.1.1.RELEASE</version>  
</dependency>  
<!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-jasper -->  
<dependency>  
    <groupId>org.apache.tomcat</groupId>  
    <artifactId>tomcat-jasper</artifactId>  
    <version>9.0.12</version>  
</dependency>  
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->  
<dependency>    
    <groupId>javax.servlet</groupId>    
    <artifactId>servlet-api</artifactId>    
    <version>3.0-alpha-1</version>    
</dependency>  
<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->  
<dependency>  
    <groupId>javax.servlet</groupId>  
    <artifactId>jstl</artifactId>  
    <version>1.2</version>  
</dependency>  
 <!-- https://mvnrepository.com/artifact/org.hibernate.validator/hibernate-validator -->  
<dependency>  
    <groupId>org.hibernate.validator</groupId>  
    <artifactId>hibernate-validator</artifactId>  
    <version>6.0.13.Final</version>  
</dependency>  

2. 创建Bean类

Employee.java

package cn.javatiku;  
  
import javax.validation.constraints.Max;  
import javax.validation.constraints.Min;  
import cn.javatiku.customvalidation.Password;  
  
public class Employee {  
    private String name;  
    //Custom annotation  
    @Password  
    private String password;  
    //Predefined annotation  
    @Min(value=18, message="must be equal or greater than 18")  
    @Max(value=45, message="must be equal or less than 45")  
    private int age;  
  
    public String getName() {  
        return name;  
    }  
  
    public void setName(String name) {  
        this.name = name;  
    }  
  
    public String getPassword() {  
        return password;  
    }  
  
    public void setPassword(String password) {  
        this.password = password;  
    }  
  
    public int getAge() {  
        return age;  
    }  
  
    public void setAge(int age) {  
        this.age = age;  
    }     
}  

3. 创建控制器类

EmployeeController.java

package cn.javatiku;  
  
import javax.validation.Valid;  
import org.springframework.stereotype.Controller;  
import org.springframework.ui.Model;  
import org.springframework.validation.BindingResult;  
import org.springframework.web.bind.annotation.ModelAttribute;  
import org.springframework.web.bind.annotation.RequestMapping;  
  
@Controller  
public class EmployeeController {  
      
    @RequestMapping("/hello")  
    public String showForm(Model theModel) {  
          
        theModel.addAttribute("emp", new Employee());  
          
        return "viewpage";  
    }  
      
    @RequestMapping("/helloagain")  
    public String processForm(  
            @Valid @ModelAttribute("emp") Employee emp,  
            BindingResult br) {  
                  
        if (br.hasErrors()) {  
            return "viewpage";  
        }  
        else {  
            return "final";  
        }  
    }  
}  

4. 创建验证注解

Password.java

package cn.javatiku.customvalidation;  
  
import java.lang.annotation.ElementType;  
import java.lang.annotation.Retention;  
import java.lang.annotation.RetentionPolicy;  
import java.lang.annotation.Target;  
  
import javax.validation.Constraint;  
import javax.validation.Payload;  
  
@Constraint(validatedBy = PasswordConstraintValidator.class)  
@Target( { ElementType.METHOD, ElementType.FIELD } )  
@Retention(RetentionPolicy.RUNTIME)  
public @interface Password {  
    //error message  
        public String message() default "must contain jtp";  
    //represents group of constraints     
        public Class<?>[] groups() default {};  
    //represents additional information about annotation  
        public Class<? extends Payload>[] payload() default {};  
}  

5. 创建验证器类

PasswordConstraintValidator.java

package cn.javatiku.customvalidation;  
  
import javax.validation.ConstraintValidator;  
import javax.validation.ConstraintValidatorContext;  
  
public class PasswordConstraintValidator implements ConstraintValidator<Password,String> {  
  
    public boolean isValid(String s, ConstraintValidatorContext cvc) {  
          
        boolean result=s.contains("jtp");  
        return result;  
    }  
}  

6. 在web.xml文件中定义控制器条目

web.xml

<?xml version="1.0" encoding="UTF-8"?>  
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  
  <display-name>SpringMVC</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>  

7. 在xml文件中定义Bean

spring-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>  
<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"  
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
    xsi:schemaLocation="  
        http://www.springframework.org/schema/beans  
        http://www.springframework.org/schema/beans/spring-beans.xsd  
        http://www.springframework.org/schema/context  
        http://www.springframework.org/schema/context/spring-context.xsd  
        http://www.springframework.org/schema/mvc  
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">  
    <!-- Provide support for component scanning -->  
    <context:component-scan base-package="cn.javatiku" />  
    <!--Provide support for conversion, formatting and validation -->  
    <mvc:annotation-driven/>  
    <!-- Define Spring MVC view resolver -->  
     <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">  
        <property name="prefix" value="/WEB-INF/jsp/"></property>  
        <property name="suffix" value=".jsp"></property>       
     </bean>  
</beans>  

8. 创建所请求的页面

index.jsp

<html>  
<body>  
<a href="hello">Click here...</a>  
</body>  
</html>  

9. 创建其他视图组件

viewpage.jsp

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>  
<html>  
<head>  
    <style>  
        .error {color:red}  
    </style>  
</head>  
<body>  
    <form:form action="helloagain" modelAttribute="emp">  
        Username: <form:input path="name" />        
        <br><br>  
          
        Password (*): <form:password path="password" />  
        <form:errors path="password" cssClass="error" />  
        <br><br>  
          
        Age (*): <form:input path="age" />  
        <form:errors path="age" cssClass="error" />  
        <br><br>  
        <input type="submit" value="Submit" />  
    </form:form>  
</body>  
</html> 

final.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>  
<!DOCTYPE html>  
<html>  
<body>  
Username: ${emp.name}<br><br>  
Password: ${emp.password}<br><br>  
Age: ${emp.age}  
<br><br>  
</body>  
</html> 

输出:

在您提供的示例中，我们输入了不包含 "jtp" 序列的密码。

现在，我们输入了包含 "jtp" 序列的密码。