你需要什么
- 大约 15 分钟
- IntelliJ IDEA或其他编辑器
- JDK 1.8或更高版本
- Maven 3.2+
你会建立什么
您将构建一个简单的Spring MVC应用程序,它接受用户输入并使用标准验证注解检查输入。您还将看到如何在屏幕上显示错误消息,以便用户可以重新输入有效的输入。
构建步骤
1、添加maven
依赖。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- 表单验证模块 -->
<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-el</artifactId>
</dependency>
2、创建一个PersonForm对象
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
public class PersonForm {
@NotNull
@Size(min=2, max=30)
private String name;
@NotNull
@Min(18)
private Integer age;
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String toString() {
return "Person(Name: " + this.name + ", Age: " + this.age + ")";
}
}
@Size(min = 2, max = 30)
只允许长度在2到30个字符之间的名称@NotNull
将不允许空值@Min(18)
将不允许值小于18
3、创建一个Web Controller
import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Controller
public class WebController implements WebMvcConfigurer {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/results").setViewName("results");
}
@GetMapping("/")
public String showForm(PersonForm personForm) {
return "form";
}
@PostMapping("/")
public String checkPersonInfo(@Valid PersonForm personForm, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
return "form";
}
return "redirect:/results";
}
}
checkPersonFormInfo
方法接受两个参数:
personForm
对象用@Valid
标记,以收集您即将构建的表单中填写的属性。bindingResult
对象,因此您可以测试并检索验证错误。
4、构建一个HTML表单
<html >
<meta charset="UTF-8" />
<body>
<form action="#" th:action="@{/}" th:object="${personForm}" method="post">
<table>
<tr>
<td>Name:</td>
<td><input type="text" th:field="*{name}" /></td>
<td th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name Error</td>
</tr>
<tr>
<td>Age:</td>
<td><input type="text" th:field="*{age}" /></td>
<td th:if="${#fields.hasErrors('age')}" th:errors="*{age}">Age Error</td>
</tr>
<tr>
<td><button type="submit">Submit</button></td>
</tr>
</table>
</form>
</body>
</html>