java - 未找到 Google 云日志记录处理程序

Question

当我将记录器指向 Google 云日志记录处理程序时，我的 Google 应用引擎本地开发服务器返回 classdef 未找到异常，如何修复此问题？

INFO: Dev App Server is now running
Can't load log handler "com.google.cloud.logging.LoggingHandler"
java.lang.ClassNotFoundException: com.google.cloud.logging.LoggingHandler
java.lang.ClassNotFoundException: com.google.cloud.logging.LoggingHandler
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.util.logging.LogManager$5.run(LogManager.java:965)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.util.logging.LogManager.loadLoggerHandlers(LogManager.java:958)
    at java.util.logging.LogManager.addLogger(LogManager.java:1165)
    at java.util.logging.LogManager.demandLogger(LogManager.java:556)
    at java.util.logging.Logger.demandLogger(Logger.java:455)
    at java.util.logging.Logger.getLogger(Logger.java:502)
    at coffee.weneed.chat.CoffeeChat.<clinit>(CoffeeChat.java:37)
    at coffee.weneed.chat.kik.KikServlet.doGet(KikServlet.java:18)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at ...

我的日志记录属性:

.level = INFO
io.grpc.netty.level=INFO
sun.net.level=INFO

coffee.weneed.chat.CoffeeChat.handlers=com.google.cloud.logging.LoggingHandler,java.util.logging.ConsoleHandler
com.google.cloud.logging.LoggingHandler.log=coffee_chat
com.google.cloud.logging.LoggingHandler.level=INFO

com.google.cloud.logging.LoggingHandler.flushLevel=SEVERE
com.google.cloud.logging.LoggingHandler.formatter=java.util.logging.SimpleFormatter
java.util.logging.SimpleFormatter.format=%3$s: %5$s%6$s

和我的系统属性:

    <system-properties>
    <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>
  </system-properties>

我已将云登录包含到maven deps中，云maven插件已安装。我只是不太明白为什么它不会加载该类。

Answer 1

You have to use code to install a custom handler in GAE 。这被描述为 feature request for GAE 。这也是 JDK 的一个已知问题:JDK-6878454: LogManager class loading inconsistent with Java EE best practices .

问题是 LogManager 使用系统类加载器来定位处理程序，但您的代码位于 Web 应用程序类加载器中，该类加载器将是子类加载器。子类加载器可以在父类中找到类，但反之则不行。这是导致 java.lang.ClassNotFoundException 的原因。

您可以关注this example setting up a custom handler setup in GAE 。这使用 ServletContextListener 来访问正确的类加载器。