fix：针对hive进行了一些优化

plugin.xml

@@ -12,6 +12,7 @@
       [2019-05-20]优化逻辑。<br/>
       [2019-05-30]实现一个可用的ClassLoader。<br/>
       [2019-05-31]修改Mysql的key为Hive。<br/>
+      [2019-05-31]考虑一下并发问题，针对hive修改了一下加载机制。<br/>
     ]]></change-notes>
     <main-package>com.fr.plugin.dialect.classloader</main-package>
     <extra-core>

src/main/java/com/fr/plugin/dialect/classloader/ClassLoaderHandler.java

@@ -20,6 +20,7 @@ import java.util.List;
 
 @EnableMetrics
 public class ClassLoaderHandler extends AbstractDataSourceDriverLoader {
+    private ClassLoader driverClassLoader;
     //插件获取jar的路径，和lib同级的driverlib目录
     public static final String DRIVER_LIB_DIR = "driverlib";
 
@@ -41,11 +42,14 @@ public class ClassLoaderHandler extends AbstractDataSourceDriverLoader {
 
     @Focus(id = "com.fr.plugin.dialect.classloader.ClassLoaderHandler", text = "", source = Original.PLUGIN)
     public ClassLoader getClassLoader() {
-        FineLoggerFactory.getLogger().info("====== Loading Mysql ClassLoader ... ======");
-        URL[] urls = getJarURLS();
-        ClassLoader cl = new DriverClassLoader(urls);
-        Thread.currentThread().setContextClassLoader(cl);
-        return cl;
+        FineLoggerFactory.getLogger().info("====== Loading Hive ClassLoader ... ======");
+        synchronized (this) {
+            if (this.driverClassLoader == null) {
+                URL[] urls = getJarURLS();
+                this.driverClassLoader = new DriverClassLoader(urls);
+            }
+            return driverClassLoader;
+        }
     }
 
 

src/main/java/com/fr/plugin/dialect/classloader/DriverClassLoader.java

@@ -33,8 +33,8 @@ public class DriverClassLoader extends URLClassLoader {
                 FineLoggerFactory.getLogger().debug("Did not find class{}, in the paths {}, try to get from common lib", name, this.getUrlStrings());
                 c = super.loadClass(name);
             }
-
             return c;
+
         }
 
     }