自定義Spring Boot內置tomcat的404頁面

spring boot 的相關404頁面配置都是針對項目路徑下的（若是配置了 context-path）

在context-path不爲空的狀況下，若是訪問路徑不帶context-path，這時候會顯示空白頁面或者是tomcat默認404頁面

這時候如何自定義內置tomcat的404頁面呢？

查看tomcat錯誤頁面的實現源碼org.apache.catalina.valves.ErrorReportValue：

report方法中先查找是否註冊了錯誤頁面，默認狀況未註冊任何錯誤頁面，而後經過sendErrorPage方法發送錯誤頁面

private boolean sendErrorPage(String location, Response response) { File file = new File(location); if (!file.isAbsolute()) { file = new File(getContainer().getCatalinaBase(), location); } if (!file.isFile() || !file.canRead()) { getContainer().getLogger().warn( sm.getString("errorReportValve.errorPageNotFound", location)); return false; } // Hard coded for now. Consider making this optional. At Valve level or // page level?
        response.setContentType("text/html"); response.setCharacterEncoding("UTF-8"); try (OutputStream os = response.getOutputStream(); InputStream is = new FileInputStream(file);){ IOTools.flow(is, os); } catch (IOException e) { getContainer().getLogger().warn( sm.getString("errorReportValve.errorPageIOException", location), e); return false; } return true; }

因爲spring boot 默認打成的jar包運行tomcat，因此必需要把404頁面放到外部，這裏先將404.html放到resource目錄下，而後啓動過程當中將頁面複製到tomcat臨時目錄，將404路徑指向該頁面就能夠了。html

這裏有兩種實現辦法：java

一、經過AOP修改默認註冊的ErrorReportValueweb

import java.io.File; import java.io.IOException; import javax.servlet.Servlet; import org.apache.catalina.startup.Tomcat; import org.apache.catalina.valves.ErrorReportValve; import org.apache.coyote.UpgradeProtocol; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.web.embedded.TomcatWebServerFactoryCustomizer; import org.springframework.boot.web.embedded.tomcat.ConfigurableTomcatWebServerFactory; import org.springframework.core.io.ClassPathResource; import org.springframework.stereotype.Component; import org.springframework.util.FileCopyUtils; import com.bc.core.util.FileUtil; @Aspect @ConditionalOnClass({ Servlet.class, Tomcat.class,  UpgradeProtocol.class,  TomcatWebServerFactoryCustomizer.class }) @Component public class TomcatCustomizerAspect { @Pointcut("execution(public void  org.springframework.boot.autoconfigure.web.embedded.TomcatWebServerFactoryCustomizer.customize(*))") public void customize() { } @After(value = "customize()") public void doAfter(JoinPoint joinPoint) throws Throwable { if (!(joinPoint.getArgs()[0] instanceof ConfigurableTomcatWebServerFactory)) { return; } ConfigurableTomcatWebServerFactory factory =  (ConfigurableTomcatWebServerFactory)  joinPoint.getArgs()[0]; addTomcat404CodePage(factory); } private static void addTomcat404CodePage(ConfigurableTomcatWebServerFactory factory) { factory.addContextCustomizers((context) -> { String path =  context.getCatalinaBase().getPath() + "/404.html"; ClassPathResource cr = new  ClassPathResource("404.html"); if (cr.exists()) { File file404 = new File(path); if (!file404.exists()) { try { FileCopyUtils.copy(cr.getInputStream(), FileUtil.openOutputStream(file404)); } catch (IOException e) { e.printStackTrace(); } } } ErrorReportValve valve = new ErrorReportValve(); valve.setProperty("errorCode.404", path); valve.setShowServerInfo(false); valve.setShowReport(false); valve.setAsyncSupported(true); context.getParent().getPipeline().addValve(valve); }); } }

二、經過自定義BeanPostProcessor添加自定義的ErrorReportValvespring

import java.io.File; import java.io.IOException; import javax.servlet.Servlet; import org.apache.catalina.startup.Tomcat; import org.apache.catalina.valves.ErrorReportValve; import org.apache.coyote.UpgradeProtocol; import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.web.embedded.TomcatWebServerFactoryCustomizer; import org.springframework.boot.web.embedded.tomcat.ConfigurableTomcatWebServerFactory; import org.springframework.core.io.ClassPathResource; import org.springframework.stereotype.Component; import org.springframework.util.FileCopyUtils; import com.bc.core.util.FileUtil; import lombok.extern.slf4j.Slf4j; @ConditionalOnClass({ Servlet.class, Tomcat.class,  UpgradeProtocol.class,  TomcatWebServerFactoryCustomizer.class }) @Component @Slf4j public class TomcatCustomizerBeanPostProcessor implements BeanPostProcessor { @Override public Object postProcessAfterInitialization(Object  bean, String beanName) throws BeansException { if (bean instanceof ConfigurableTomcatWebServerFactory) { ConfigurableTomcatWebServerFactory configurableTomcatWebServerFactory = (ConfigurableTomcatWebServerFactory) bean; addTomcat404CodePage(configurableTomcatWebServerFactory); } return  BeanPostProcessor.super.postProcessAfterInitialization(bean, beanName); } private static void addTomcat404CodePage(ConfigurableTomcatWebServerFactory factory) { factory.addContextCustomizers((context) -> { String tomcatTempPath = context.getCatalinaBase().getPath(); log.info("tomcat目錄：{}", tomcatTempPath); String path = tomcatTempPath + "/404.html"; ClassPathResource cr = new  ClassPathResource("404.html"); if (cr.exists()) { File file404 = new File(path); if (!file404.exists()) { try { FileCopyUtils.copy(cr.getInputStream(), FileUtil.openOutputStream(file404)); } catch (IOException e) { e.printStackTrace(); } } } ErrorReportValve valve = new ErrorReportValve(); valve.setProperty("errorCode.404", path); valve.setShowServerInfo(false); valve.setShowReport(false); valve.setAsyncSupported(true); context.getParent().getPipeline().addValve(valve); }); } }

上面兩種辦法，都就能夠達到，若是項目訪問帶項目名，訪問任意錯誤路徑（非項目路徑下的路徑），指向自定義的404頁面apache