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Validação personalizada do Spring MVC

O framework Spring MVC nos permite executar validações personalizadas. Neste caso, declaramos nossas próprias anotações. Podemos executar validações com base em nossa lógica de negócios.

Exemplo de validação personalizada do Spring MVC

Neste exemplo, usamos tanto comentários pré-definidos quanto comentários personalizados para validar a entrada do usuário。

1、adicionar dependências ao arquivo 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、Criar anotação de validador

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 {
    //mensagem de erro
        public String message() default "must contain jtp";
    //representa grupo de restrições   
        public Class<?>[] groups() default {};
    //Representa informações adicionais sobre a anotação
        public Class<? extends Payload>[] payload() default {};
}

5Criar classe 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 do controlador no arquivo 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 no arquivo 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">
        Nome de Usuário: <form:input path="name"} />     
        <br><br>
        
        Senha (*): <form:password path="password" />
        <form:errors path="password" cssClass="error" />
        <br><br>
        
        Idade (*): <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>
Nome de Usuário: ${emp.name}<br><br>
Senha: ${emp.password}<br><br>
Idade: ${emp.age}
<br><br>
</body>
</html>

Saída:



Aqui, ao digitarmos a senha, não precisamos inserir a sequência "jtp".



Agora, a senha que estamos digitando possui a sequência "jtp".