[GitHub] [skywalking] HendSame commented on issue #3661: "java -ext.dirs" is not supported

[GitBox <gi...@apache.org>]

HendSame commented on issue #3661:
URL: https://github.com/apache/skywalking/issues/3661#issuecomment-768278507


   I have a question: 
   Do you have to load the depency libs by "ExtClassLoader"?  @jackiepon31 
   
   "-Xbootclasspath/a:"  can  not  solve this problem？By the way ,we can use the BootstrapClassLoader to load the them.
   We  can run the oldWay.jar  such as: 
   
   ```
   java -javaagent:/{skywalking-agent-dir}/skywalking-agent-abm.jar
   -Xbootclasspath/a:/{your}.jar
   -Dskywalking.agent.service_name=serverName
   -Dskywalking.collector.backend_service=127.0.0.1:11800
   
   Maybe  multiple  jar  in one directory:
   
   java -javaagent:/{skywalking-agent-dir}/skywalking-agent-abm.jar
   -Xbootclasspath/a:/{jar-directory}
   -Dskywalking.agent.service_name=serverName
   -Dskywalking.collector.backend_service=127.0.0.1:11800
   ```
   
   If don't want to do that like the above 
   Just like @jackiepon31  said：
   “I suggest to add SkyWalking-agent.jar or its dirs to classpath to make the load mechanism compatible with old packaing way instead of spring-boot fat jar.” by using the  BootstrapClassLoader to load the them, rather than the ExtClassLoader ,is OK? @wu-sheng .Because ExtClassLoader can't seem to do it。
    We can use "instrumentation.appendToBootstrapClassLoaderSearch(jarFile)":
   ```
   File basePath = ProbePackagePath.getPath();
               File classPathDictionary = new File(basePath, "classpath");
               if (classPathDictionary.exists() && classPathDictionary.isDirectory()) {
                   String[] jarFileNames = classPathDictionary.list((dir, name) -> name.endsWith(".jar"));
                   for (String fileName : jarFileNames) {
                       JarFile jarFile = new JarFile(classPathDictionary + "/" + fileName);
                       instrumentation.appendToBootstrapClassLoaderSearch(jarFile);
                   }
               }
   ```
   "classpath" is a dictionary that has the jars which need  to load to  classpath;
   ```
   skywalking
         -- classpath
              -- 1.jar
              -- 2.jar
         -- skywalking-agent-abm.jar
   ```
   


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