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，我们声明自己的注释。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，我们同时使用预定义的注释和自定义注释来验证用户输入。

1、将依赖项添加到pom.xml文件。

pom.xml

示例

<!-- 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

示例

package com.nhooo;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import com.nhooo.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

示例

 package com.nhooo;
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、创建验证器注释

Password.java

示例

package com.nhooo.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 {};
    //表示关于注解的附加信息
        public Class<? extends Payload>[] payload() default {};
}

5、创建验证器类

PasswordConstraintValidator.java

示例

package com.nhooo.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文件中提供控制器的条目

web.xml

示例

<?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

示例

<?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="com.nhooo" />
    <!--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、创建请求的页面

index.jsp

示例

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

9、创建其他视图组件

viewpage.jsp

示例

<%@ 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

示例

<%@ 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:

Spring MVC自定义验证