簡單解決復雜的Oracle IAS問題

筆者做了一個小的系統輔助功能，可以周期性訪問某個URL、執行某個SQL語句or 執行某個系統命令 。

執行SQL語句和系統命令比較簡單，這裡不再詳述，主要說一下訪問某個URL。

實際上JDK自身已有工具類用於創建HTTP請求，類名是：java.net.HttpURLConnection，但考慮到基礎類通常比 較粗糙，很多情況要自己考慮和處理，就轉頭去Google了下，發現果然有開源的工具包可以使用，幾個工具包中以HttpClient較為常用，而且是apache的東東，於是決定采用HttpClient。

從apache上 down了包commons-httpclient-3.1.jar和commons-codec-1.3.jar兩個包，後者是HttpClient依賴的包。

幫助寫的很好，即便是像我這樣英文很爛，也能很快上手。

public　boolean　 visitURL(String　url)　{

//　Commons　HttpClient　3.1
HttpClient　client　=　new　HttpClient();
HttpMethod　method　=　new　GetMethod(url);

//　Provide　custom　retry　handler　is　necessary
method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,　new　 DefaultHttpMethodRetryHandler(3,　false));

boolean　rs　=　false;

try　{

//　Execute　the　method.
int　statusCode　=　client.executeMethod(method);

if　(statusCode　!=　HttpStatus.SC_OK)　{
logger.error("Method　failed:　"　+　method.getStatusLine());
}
else　{
rs　=　true;
}

}　catch　(HttpException　e)　{
logger.error("Fatal　protocol　violation:　"　+　e.getMessage());
}　catch　(IOException　e)　{
logger.error("Fatal　transport　error:　"　+　e.getMessage());
}　finally　{
//　Release　the　connection.
method.releaseConnection();
}

return　rs;
}

本機Tomcat下run一下，工作正常，隨即丟到服務器（Oracle IAS環境）上測試，程序 應該出乎意料的報了個錯。

09/03/16　19:03:43　java.lang.NoClassDefFoundError
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpMethodBase.writeRequestLine (HttpMethodBase.java:2015)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpMethodBase.writeRequest (HttpMethodBase.java:1864)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpMethodBase.execute (HttpMethodBase.java:975)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry (HttpMethodDirector.java:368)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpMethodDirector.executeMethod (HttpMethodDirector.java:164)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpClient.executeMethod (HttpClient.java:437)
09/03/16　19:03:43　at　org.apache.commons.httpclient.HttpClient.executeMethod (HttpClient.java:324)
09/03/16　19:03:43　at　com.zbht.util.TimerTaskManager.runURLTask (TimerTaskManager.java:237)
09/03/16　19:03:43　at　_system._timer__task._test._jspService(_test.java:182)
09/03/16　19:03:43　at　com.orionserver.http.OrionHttpJspPage.service (OrionHttpJspPage.java:59)
09/03/16　19:03:43　at　oracle.jsp.runtimev2.JspPageTable.service(JspPageTable.java:462)
09/03/16　19:03:43　at　oracle.jsp.runtimev2.JspServlet.internalService (JspServlet.java:594)
09/03/16　19:03:43　at　oracle.jsp.runtimev2.JspServlet.service(JspServlet.java:518)
09/03/16　19:03:43　at　javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
09/03/16　19:03:43　at　com.evermind.server.http.ServletRequestDispatcher.invoke (ServletRequestDispatcher.java:713)
09/03/16　19:03:43　at　com.evermind.server.http.ServletRequestDispatcher.forwardInternal (ServletRequestDispatcher.java:370)
09/03/16　19:03:43　at　com.evermind.server.http.HttpRequestHandler.doProcessRequest (HttpRequestHandler.java:871)
09/03/16　19:03:43　at　com.evermind.server.http.HttpRequestHandler.processRequest (HttpRequestHandler.java:453)
09/03/16　19:03:43　at　com.evermind.server.http.AJPRequestHandler.run (AJPRequestHandler.java:302)
09/03/16　19:03:43　at　com.evermind.server.http.AJPRequestHandler.run (AJPRequestHandler.java:190)
09/03/16　19:03:43　at　oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run (ServerSocketReadHandler.java:260)
09/03/16　19:03:43　at　com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run (ReleasableResourcePooledExecutor.java:303)
09/03/16　19:03:43　at　java.lang.Thread.run(Thread.java:595)