Spring 自定义 404 错误页面教程展示了如何在 Spring Web 应用中创建自定义 404 错误页面。
Spring 是用于创建企业应用的流行 Java 应用框架。
404 代码
HTTP 404 或 404 未找到是计算机网络通信中的超文本传输协议（HTTP）标准响应代码，用于指示客户端能够与给定服务器进行通信，但是服务器找不到所请求的资源。
Spring 自定义 404 错误页面示例
以下应用使用创建自定义 404 错误页面。 默认情况下，当找不到资源时，将显示 Tomcat 的 404 错误页面。
src├───main│ ├───java│ │ └───com│ │ └───zetcode│ │ ├───config│ │ │ MyWebInitializer.java│ │ │ WebConfig.java│ │ └───controller│ │ ControllerAdvisor.java│ │ MyController.java│ └───resources│ │ logback.xml│ └───templates│ │ index.html│ └───error│ 404.html└───test └───java
这是项目结构。
pom.xml
<?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>com.zetcode</groupId> <artifactId>custom404page</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.2.3</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>5.1.3.RELEASE</version> </dependency> <dependency> <groupId>org.thymeleaf</groupId> <artifactId>thymeleaf-spring5</artifactId> <version>3.0.11.RELEASE</version> </dependency> <dependency> <groupId>org.thymeleaf</groupId> <artifactId>thymeleaf</artifactId> <version>3.0.11.RELEASE</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>3.2.2</version> </plugin> </plugins> </build></project>
在pom.xml文件中，我们具有以下依存关系：logback-classic，javax.servlet-api，spring-webmvc和thymeleaf-spring5以及thymeleaf。
resources/logback.xml
<?xml version="1.0" encoding="UTF-8"?><configuration> <logger name="org.springframework" level="ERROR"/> <logger name="com.zetcode" level="INFO"/> <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n </Pattern> </encoder> </appender> <root> <level value="INFO" /> <appender-ref ref="consoleAppender" /> </root></configuration>这是logback.xml配置文件。
com/zetcode/config/MyWebInitializer.java
package com.zetcode.config;import org.springframework.context.annotation.Configuration;import org.springframework.web.context.WebApplicationContext;import org.springframework.web.servlet.DispatcherServlet;import org.springframework.web.servlet.FrameworkServlet;import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;@Configurationpublic class MyWebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class<?>[] getRootConfigClasses() { return null; } @Override protected Class<?>[] getServletConfigClasses() { return new Class[]{WebConfig.class}; } @Override protected String[] getServletMappings() { return new String[]{"/"}; } @Override protected FrameworkServlet createDispatcherServlet(WebApplicationContext servletAppContext) { var dispatcher = (DispatcherServlet) super.createDispatcherServlet(servletAppContext); dispatcher.setThrowExceptionIfNoHandlerFound(true); return dispatcher; }}MyWebInitializer初始化 Spring Web 应用。 它包含一个配置类：WebConfig。
@Overrideprotected FrameworkServlet createDispatcherServlet(WebApplicationContext servletAppContext) { var dispatcher = (DispatcherServlet) super.createDispatcherServlet(servletAppContext); dispatcher.setThrowExceptionIfNoHandlerFound(true); return dispatcher;}使用setThrowExceptionIfNoHandlerFound()，我们将 Spring 配置为在找不到资源时抛出NoHandlerFoundException。 如果我们在此行中添加注释，则会显示 Web 服务器的 404 错误页面。
com/zetcode/config/WebConfig.java
package com.zetcode.config;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.ViewResolver;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;import org.thymeleaf.spring5.SpringTemplateEngine;import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver;import org.thymeleaf.spring5.view.ThymeleafViewResolver;@Configuration@EnableWebMvc@ComponentScan(basePackages = {"com.zetcode"})public class WebConfig implements WebMvcConfigurer { @Autowired private ApplicationContext applicationContext; @Bean public SpringResourceTemplateResolver templateResolver() { var templateResolver = new SpringResourceTemplateResolver(); templateResolver.setApplicationContext(applicationContext); templateResolver.setPrefix("classpath:/templates/"); templateResolver.setSuffix(".html"); return templateResolver; } @Bean public SpringTemplateEngine templateEngine() { var templateEngine = new SpringTemplateEngine(); templateEngine.setTemplateResolver(templateResolver()); templateEngine.setEnableSpringELCompiler(true); return templateEngine; } @Bean public ViewResolver viewResolver() { var resolver = new ThymeleafViewResolver(); var registry = new ViewResolverRegistry(null, applicationContext); resolver.setTemplateEngine(templateEngine()); registry.viewResolver(resolver); return resolver; }}WebConfig配置 Thymeleaf 模板引擎。 Thymeleaf 模板文件位于类路径的templates子目录中。
com/zetcode/controller/MyController.java
package com.zetcode.controller;import org.springframework.http.MediaType;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.GetMapping;import java.time.LocalDateTime;@Controllerpublic class MyController { @GetMapping(value = "/", produces = MediaType.TEXT_HTML_VALUE) public String home(Model model) { model.addAttribute("now", LocalDateTime.now()); return "index"; }} MyController包含主页的一种路由。
com/zetcode/controller/ControllerAdvisor.java
package com.zetcode.controller;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.NoHandlerFoundException;@ControllerAdvicepublic class ControllerAdvisor { @ExceptionHandler(NoHandlerFoundException.class) public ModelAndView handle(Exception ex) { var mv = new ModelAndView(); mv.addObject("message", ex.getMessage()); mv.setViewName("error/404"); return mv; }}ControllerAdvisor包含NoHandlerFoundException的处理程序。 它显示404.html错误页面，位于resources/templates/error/404.html中。
resources/templates/error/404.html
<!doctype html><html xmlns:th="http://www.thymeleaf.org"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Resource not found</title></head><body><h2>404 - resource not found</h2><p> <span th:text="${message}" th:remove="tag"></span></p></body></html>404.html是我们的自定义 404 错误页面。
resources/templates/index.html
<!DOCTYPE html><html xmlns:th="http://www.thymeleaf.org"><head> <meta charset="UTF-8"> <title>Home page</title></head><body><p> This is home page.</p><p> Today is <span th:text="${now}"></span></p></body></html>这是主页。
在本教程中，我们在 Spring 应用中创建了一个自定义 404 错误页面。
