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我刚刚从 netbeans 切换到 springsource 工具套件，但遇到了一个问题：

我已经下载了 mysql-connector-java-5.1.20-bin.jar 将文件添加到库中，但我仍然收到此警告：

java.lang.ClassNotFoundException: com.mysql.jdbc
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:186)
    at database.Database.checkConnection(Database.java:20)
    at database.UserDatabase.getUser(UserDatabase.java:114)
    at register.processRequest(register.java:30)
    at register.doGet(register.java:74)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.invoke(HttpRequestOperationCollectionValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
java.lang.NullPointerException
    at register.processRequest(register.java:31)
    at register.doGet(register.java:74)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.invoke(HttpRequestOperationCollectionValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
jun 06, 2012 7:59:12 PM org.apache.catalina.core.StandardContext reload
INFO: Reloading Context with name [/Burgerdemocratie] has started
jun 06, 2012 7:59:12 PM org.apache.catalina.core.ApplicationContext log
INFO: Destroying Spring FrameworkServlet 'appServlet'

这是我认为很标准的连接代码：

public class Database {

    protected static Connection connection = null;
    public static boolean checkConnection() throws Exception {
        if (connection == null || connection.isClosed()) {
            String driver = "com.mysql.jdbc.Driver";
            String url = "jdbc:mysql://localhost:3306/2012gwtgr2";
            String login = "gwx2";
            String pass = "VCxxxR";
            try {
                Class.forName(driver).newInstance();
                connection = DriverManager.getConnection(url, login, pass);

            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        if (connection == null || connection.isClosed()) {
            return false;
        } else {
            return true;
        }
    }

}

有人能帮助我吗？

亲切的问候，

4

2 回答 2

3

如果您有一个 Web 项目，那么它应该放在 WebContent/WEB-INF/lib 文件夹下，并将它也添加到您的库中。这应该可以解决问题。

于 2012-06-06T20:10:13.940 回答
-1

如果您有一个 Web 项目，那么它应该放在 WebContent/WEB-INF/lib 文件夹下，并将它也添加到您的库中。这应该可以解决问题。

尝试这个！

于 2012-06-07T06:31:41.810 回答