Spring Boot 2 + Thymeleaf：服务器端表单验证

2019-10-25 06:48:06来源：博客园阅读 ()

表单验证分为前端验证和服务器端验证。
服务器端验证方面，Java提供了主要用于数据验证的JSR 303规范，而Hibernate Validator实现了JSR 303规范。
项目依赖加入spring-boot-starter-thymeleaf时，默认就会加入Hibernate Validator的依赖。

开发环境：IntelliJ IDEA 2019.2.2
Spring Boot版本：2.1.8

新建一个名称为demo的Spring Boot项目。

1、pom.xml

       <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

2、src/main/java/com/example/demo/User.java

package com.example.demo;

import org.hibernate.validator.constraints.Length;

import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;

public class User {
    @NotBlank(message = "用户名不能为空")
    String name;
    @Length(min = 11, max = 11, message = "手机号长度必须11位")
    String phone;
    @Size(min = 6, max = 20, message = "密码长度6-20位")
    String password;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

3、src/main/java/com/example/demo/FormController.java

package com.example.demo;

import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.validation.Valid;
import java.util.List;

@Controller
public class FormController {
    @RequestMapping("/{form}")
    public String form(@PathVariable String form, @ModelAttribute User user){
        return form;
    }

    @PostMapping("/submit")
    public String submit(@Valid User user, BindingResult result){
        if (result.hasErrors()) {
            List<ObjectError> list = result.getAllErrors();
            for (ObjectError error : list) {
                System.out.println(error.getDefaultMessage());
            }
            return "form";
        }
        //业务逻辑处理
        return "form";
    }

}

4、src/main/resources/templates/form.html

前端通过#fields对象输出错误信息有2种方式，1种是在每个字段后面输出，另1种是全部在一起输出。

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>表单的提交处理</title>
    <style>
        .fieldError{color: red}
    </style>
</head>
<body>
    <form method="post" th:action="@{/submit}" th:object="${user}">
       <table>
           <tr>
               <td>用户名：</td>
               <td><input type="text" th:field="*{name}" />
                   <span class="fieldError" th:if="${#fields.hasErrors('*{name}')}" th:errors="*{name}"></span>
               </td>
           </tr>
           <tr>
               <td>手机号：</td>
               <td><input type="text" th:field="*{phone}" />
                   <span class="fieldError" th:if="${#fields.hasErrors('*{phone}')}" th:errors="*{phone}"></span>
               </td>
           </tr>
           <tr>
               <td>密码：</td>
               <td><input type="text" th:field="*{password}" />
                   <span class="fieldError" th:if="${#fields.hasErrors('*{password}')}" th:errors="*{password}"></span>
               </td>
           </tr>
           <tr>
               <td colspan="2">
                   <input type="submit" value="提交" />
                   <div th:each="err : ${#fields.errors('*')}">
                       <span th:text="${err}" class="fieldError"></span>
                   </div>
               </td>
           </tr>
       </table>
    </form>
</body>
</html>

启动服务后，浏览器访问http://localhost:8080/form，点击提交按钮，结果如下：