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Validación personalizada de Spring MVC

El framework Spring MVC nos permite realizar validaciones personalizadas. En este caso, declaramos nuestras propias anotaciones. Podemos realizar validaciones según nuestra lógica de negocio.

Ejemplo de validación personalizada de Spring MVC

En este ejemplo, utilizamos tanto comentarios predefinidos como comentarios personalizados para validar la entrada del usuario.

1、agregar las dependencias al archivo pom.xml.

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 com.w3codebox;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import com.w3codebox.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 com.w3codebox;
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、create validation annotation

Password.java

package com.w3codebox.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";
    //representa grupo de restricciones   
        public Class<?>[] groups() default {};
    //Representa información adicional sobre la anotación
        public Class<? extends Payload>[] payload() default {};
}

5Crear clase validadora

PasswordConstraintValidator.java

package com.w3codebox.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;
    }
}

6Definir entradas del controlador en el archivo web.xml

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>

7Definir Bean en el archivo xml

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="com.w3codebox" />
    <!--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

<html>
<body>
<a href="hello">Click here...</a>/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">
        Nombre de usuario: <form:input path="name"} />     
        <br><br>
        
        Contraseña (*): <form:password path="password" />
        <form:errors path="password" cssClass="error" />
        <br><br>
        
        Edad (*): <form:input path="age" />
        <form:errors path="age" cssClass="error" />
        <br><br>
        <input type="submit" value="Enviar" />
    </form:form>
</body>
</html>

final.jsp

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

Salida:



Aquí, al ingresar la contraseña, no es necesario ingresar la secuencia "jtp".



Ahora, las contraseñas que ingresamos tienen la secuencia "jtp".