Spring MVC验证

Spring MVC Form Validation与Bean Validation API

此示例显示如何使用Java注释在没有任何xml的情况下使用Bean Validation API验证Spring MVC中的表单。用户将被建议输入他们的注册数据，验证者将检查其有效性。

首先在项目中添加以下依赖项：

Bean Validation API

Hibernate Validator Engine

dependencies {
    compile group: 'javax.validation', name: 'validation-api', version: '1.1.0.Final'
    compile group: 'org.hibernate', name: 'hibernate-validator', version: '5.2.4.Final'
}

创建模型类

创建模型类User如下：

import org.hibernate.validator.constraints.Email;
import org.springframework.format.annotation.DateTimeFormat;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Past;
import javax.validation.constraints.Size;
import java.util.Date;
public class User {
    @NotNull(message = "Please input your email.")
    @Email(message = "Email format is wrong.")
    private String email;
    @NotNull(message = "{user.password.notNull}")
    @Size(min = 8, max = 16, message = "{user.password.size}")
    private String password;
    @NotNull(message = "{user.age.notNull}")
    @Min(18)
    @Max(100)
    private Integer age;
    @NotNull(message = "{user.birthday.notNull}")
    @DateTimeFormat(pattern = "dd.MM.yyyy")
    @Past(message = "{user.birthday.past}")
    private Date birthday;
    // getters, setters
}

这里使用一些JSR 303注释：@NotNull，@Size，@Min，@Max和@Past以及由hibernate验证器实现提供的一些附加注释：@Email，@DateTimeFormat。

请注意，在其注释中指定了email 字段的错误消息。而在messages.properties文件中指定password，age 和birthday 字段的错误消息，以便演示验证错误消息的外部化。这个文件应放在resources文件夹下：

user.password.notNull = Password field cannot be empty.
user.password.size = Password must be between {min} and {max} characters in length.
user.age.notNull = Please enter your age.
user.birthday.notNull = Please enter your birthday.
user.birthday.past = That's impossible.
typeMismatch=Please use dd.MM.yyyy format

对于messageSource()与bean.setBasename("classpath:messages"); 代码和validator() bean也必须配置以及注释：

@Configuration
@PropertySource("application.properties")
public class AppConfig extends WebMvcConfigurerAdapter {
    @Bean
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource bean = new ReloadableResourceBundleMessageSource();
        bean.setBasename("classpath:messages");
        bean.setDefaultEncoding("UTF-8");
        return bean;
    }
    @Bean
    public LocalValidatorFactoryBean validator() {
        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
        bean.setValidationMessageSource(messageSource());
        return bean;
    }
    @Override
    public Validator getValidator() {
        return validator();
    }
}

另外配置类mu使用@PropertySource（“application.properties”）注释，并且必须将jsp页面的路径添加到此文件，如下所示：

1 2	spring.mvc.view.prefix=/WEB-INF/jsp/ spring.mvc.view.suffix=.jsp

创建FormController类

现在在controller 类中，通过javax.validation包中的@Valid注释注释正在备份表单的模型对象。

Spring MVC将使用@Valid注释来验证模型对象，并将其属性与使用Spring的表单标签的JSP表单的输入绑定。任何约束违反将暴露为BindingResult对象中的错误，因此我们可以在控制器的方法中检查违例。

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import javax.validation.Valid;
import java.util.HashMap;
import java.util.Map;
@Controller
public class FormController {
    private Map<String, User> users = null;
    public FormController() {
        users = new HashMap<String, User>();
    }
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String viewRegister(Map<String, Object> model) {
        User user = new User();
        model.put("user", user);
        return "register";
    }
    @RequestMapping(value = "/register", method = RequestMethod.POST)
    public String doRegister(@Valid User user, BindingResult result, Model model) {
        if (result.hasErrors()) {
            return "register";
        }
        model.addAttribute("user", user);
        users.put(user.getEmail(), user);
        return "registerSuccess";
    }
}

创建JSP输入表单

添加具有以下内容的register.jsp文件：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>User Form Page</title>
<style>
.error {
    color: #ff0000;
    font-weight: bold;
}
</style>
</head>
<body>
    <form:form method="POST" commandName="user" action="register">
        <table>
            <tr>
                <td>Email:</td>
                <td><form:input path="email" placeholder="Email"/></td>
                <td><form:errors path="email" cssClass="error" /></td>
            </tr>
            <tr>
                <td>Password:</td>
                <td><form:password path="password" placeholder="Password"/></td>
                <td><form:errors path="password" cssClass="error" /></td>
            </tr>
            <tr>
                <td>Age:</td>
                <td><form:input path="age" placeholder="Age"/></td>
                <td><form:errors path="age" cssClass="error" /></td>
            </tr>
            <tr>
                <td>Birthday:</td>
                <td><form:input path="birthday" placeholder="dd.MM.yyyy"/></td>
                <td><form:errors path="birthday" cssClass="error" /></td>
            </tr>
            <tr>
                <td colspan="3"><input type="submit" value="Register"></td>
            </tr>
        </table>
    </form:form>
</body>
</html>

通常，当发生任何验证错误时，我们会将输入表单返回给用户。在JSP表单中，我们可以使用Spring的形式错误标记（如）显示验证错误消息。

创建JSP Success页面

将显示registerSuccess.jsp页面，以防用户输入所有数据有效。这里是代码：

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ page session="false" %>
<html>
<head>
    <title>Success</title>
</head>
<body>
<h3>User Registered Successfully.</h3>
<strong>User Email: ${user.email}</strong><br>
<strong>User Age: ${user.age}</strong><br>
<strong>User Birthday: <fmt:formatDate value="${user.birthday}" type="date" pattern="dd.MM.yyyy"/></strong><br>
</body>
</html>

启动应用程序，转到http://localhost:8080/