无法为MS Microsoft SQL加载jdbc数据库驱动程序

Question

我按照this page上报告的说明尝试在Servlet和MS SQL SERVER 2012之间建立连接

这是我的代码：

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    PrintWriter out = response.getWriter();
    try {
        Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
    } catch (ClassNotFoundException e) {
        out.println("Can't load database driver");
        e.printStackTrace();
        return;
    }

但是，当我运行servlet时，我收到以下错误消息：

java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1333)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1167)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at demo.Connect.doGet(Connect.java:42)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

我的第一个怀疑是我弄乱了JDBC驱动程序的类路径，但我进行了三重检查，看起来没问题，实际上我可以看到库中的sqljdbc.jar（见图）：

我也尝试了sqljdbc4.jar版本，但结果是一样的。

是否有人能够找出问题所在以及如何解决问题？

Answer 1

你是对的：CLASSPATH是关键。

对于“普通”Java / JDBC应用程序，使用Microsoft安装程序中sqljdbc4.jar的位置，Windows CLASSPATH通常应为：

CLASSPATH =.;C:\Program Files\Microsoft JDBC Driver 4.0 for SQL Server\sqljdbc_4.0\enu\sqljdbc.jar

对于部署为.war文件的servlet，sqljdbc4.jar应该在WEB-INF/lib。

问：您是否检查了实际的.war文件（和/或已部署的war）以确保sqljdbc4.jar实际位于WEB-INF / lib中？