站長資訊網spring boot 的相關404頁面配置都是針對項目路徑下的（如果配置了 context-path）
在context-path不為空的情況下，如果訪問路徑不帶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方法中先查找是否注冊了錯誤頁面，默認情況未注冊任何錯誤頁面，然后通過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;
}
由于spring boot 默認打成的jar包運行tomcat，所以必須要把404頁面放到外部，這里先將404.html放到resource目錄下，然后啟動過程中將頁面復制到tomcat臨時目錄，將404路徑指向該頁面就可以了。
這里有兩種實現辦法：
1、通過AOP修改默認注冊的ErrorReportValue
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);
});
}
}
2、通過自定義BeanPostProcessor添加自定義的ErrorReportValve
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，都就可以達到，如果項目訪問帶項目名，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
