SpringBoot實戰(九)之Validator
阿新 • • 發佈：2018-08-04
.com path del emp () www 代碼行數 syn 圖片
表單驗證，是最為常見的，今天演示的是利用hibernate-validtor進行校驗，有的時候，雖然前端方面通過jQuery或者require.js校驗框架進行校驗，可以減輕服務器的壓力和改善用戶體驗，但是比如第三方請求接口方面也需要校驗，在Controller裏面套著一大堆if-elseif-else等等，兩層嵌套還好，三層或者三層以上就不好了，日子久了繼續嵌套，就會導致後面變得難以維護。我有一個朋友在一家國企，據他所說，他遇到的最爛代碼是if-else if裏面套者十幾層，而且一個類的代碼居然上千行，正常合理情況，當達到上千行代碼就要考慮抽象繼承或者多態，再設計模式了。設計模式，我不懂，只是了解，這裏就不提了，後續博文會講到設計模式的。
這裏說Validator的意義在於，通過註解減少if-else等重復判斷代碼，從而使Java代碼行數減少，因為加載類中的代碼是需要時間的。代碼行數減少，意味著加載時間減少，從而提高代碼效率。
演示示例如下:
一、導入maven依賴
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.springframework</groupId>
<artifactId>gs-validating-form-input</artifactId>
<version>0.1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.8.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.4.1.Final</version>
</dependency>
<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>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-el</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
二、編寫實體
package hello; 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 + ")"; } }
三、編寫Controller
package hello; import java.util.List; import javax.validation.Valid; import org.springframework.format.FormatterRegistry; import org.springframework.http.converter.HttpMessageConverter; import org.springframework.stereotype.Controller; import org.springframework.validation.BindingResult; import org.springframework.validation.MessageCodesResolver; import org.springframework.validation.Validator; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.method.support.HandlerMethodArgumentResolver; import org.springframework.web.method.support.HandlerMethodReturnValueHandler; import org.springframework.web.servlet.HandlerExceptionResolver; import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer; import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer; import org.springframework.web.servlet.config.annotation.CorsRegistry; import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer; import org.springframework.web.servlet.config.annotation.InterceptorRegistry; import org.springframework.web.servlet.config.annotation.PathMatchConfigurer; import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry; import org.springframework.web.servlet.config.annotation.ViewControllerRegistry; import org.springframework.web.servlet.config.annotation.ViewResolverRegistry; 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 "/results"; } @Override public void addArgumentResolvers(List<HandlerMethodArgumentResolver> arg0) { // TODO Auto-generated method stub } @Override public void addCorsMappings(CorsRegistry arg0) { // TODO Auto-generated method stub } @Override public void addFormatters(FormatterRegistry arg0) { // TODO Auto-generated method stub } @Override public void addInterceptors(InterceptorRegistry arg0) { // TODO Auto-generated method stub } @Override public void addResourceHandlers(ResourceHandlerRegistry arg0) { // TODO Auto-generated method stub } @Override public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> arg0) { // TODO Auto-generated method stub } @Override public void configureAsyncSupport(AsyncSupportConfigurer arg0) { // TODO Auto-generated method stub } @Override public void configureContentNegotiation(ContentNegotiationConfigurer arg0) { // TODO Auto-generated method stub } @Override public void configureDefaultServletHandling(DefaultServletHandlerConfigurer arg0) { // TODO Auto-generated method stub } @Override public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> arg0) { // TODO Auto-generated method stub } @Override public void configureMessageConverters(List<HttpMessageConverter<?>> arg0) { // TODO Auto-generated method stub } @Override public void configurePathMatch(PathMatchConfigurer arg0) { // TODO Auto-generated method stub } @Override public void configureViewResolvers(ViewResolverRegistry arg0) { // TODO Auto-generated method stub } @Override public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> arg0) { // TODO Auto-generated method stub } @Override public void extendMessageConverters(List<HttpMessageConverter<?>> arg0) { // TODO Auto-generated method stub } @Override public MessageCodesResolver getMessageCodesResolver() { // TODO Auto-generated method stub return null; } @Override public Validator getValidator() { // TODO Auto-generated method stub return null; } }
四、編寫html代碼
form.html
<html xmlns:th="http://www.thymeleaf.org"> <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>
result.html
<html xmlns:th="http://www.thymeleaf.org"> <body> Congratulations! You are old enough to sign up for this site. </body> </html>
五、編寫配置文件
application.properties
server.port=8080
spring.thymeleaf.cache=false
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.check-template-location=true
spring.thymeleaf.suffix=.html
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.content-type=text/html
spring.thymeleaf.mode=HTML5
六、編寫啟動類
package hello; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication public class Application { public static void main(String[] args) throws Exception { SpringApplication.run(Application.class, args); } }
最後運行main方法，在瀏覽器輸入localhost:8080/
會出現對應的表單頁面，輸入不合法會出現提示，表示驗證成功
SpringBoot實戰(九)之Validator