Question

我正在使用Intellij进行servlet项目并使用maven

 <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>6.0.6</version>
 </dependency>

据我所知，在tomcat webserver上部署war时，这应该处理所有类路径相关的问题。

但我得到了

08-Apr-2017 13：40：37.047 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory部署Web 应用程序目录/ Applications / tomcat / webapps / manager 08-Apr-2017 13：40：37.092 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory部署 Web应用程序目录/ Applications / tomcat / webapps / manager has 完成44 ms java.lang.ClassNotFoundException： com.mysql.jdbc.Driver at org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1285）在 org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1119） at java.lang.Class.forName0（Native Method）at java.lang.Class.forName（Class.java:264）at com.saurabh.testdb.TestDBServlet.doGet（TestDBServlet.java:34）at at javax.servlet.http.HttpServlet.service（HttpServlet.java:635）at at javax.servlet.http.HttpServlet.service（HttpServlet.java:742）at at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:230）在 org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:165）在 org.apache.tomcat.websocket.server.WsFilter.doFilter（WsFilter.java:52）在 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain.java:192）在 org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:165）在 org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:198）在 org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:96）在 org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:478）在 org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:140）在 org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:80）在 org.apache.catalina.valves.AbstractAccessLogValve.invoke（AbstractAccessLogValve.java:624）在 org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:87）在 org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:341）在 org.apache.coyote.http11.Http11Processor.service（Http11Processor.java:783）在 org.apache.coyote.AbstractProcessorLight.process（AbstractProcessorLight.java:66）在 org.apache.coyote.AbstractProtocol $ ConnectionHandler.process（AbstractProtocol.java:798）在 org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1441）在 org.apache.tomcat.util.net.SocketProcessorBase.run（SocketProcessorBase.java:49）在 java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1142）在 java.util.concurrent.ThreadPoolExecutor中的$ Worker.run（ThreadPoolExecutor.java:617）在 org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）在java.lang.Thread.run（Thread.java:745）

这是我加载驱动程序的代码

package com.saurabh.testdb;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;

@WebServlet("/TestDBServlet")
public class TestDBServlet extends HttpServlet {

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    //set up connection variable
    String jdbcUrl = "jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false";
    String user = "springstudent";
    String pass = "sringstudent";
    String driver = "com.mysql.jdbc.Driver";

    try {

        PrintWriter out = resp.getWriter();

        out.println("Connecting to database: " + jdbcUrl);

        Class.forName(driver);

        Connection myConn = DriverManager.getConnection(jdbcUrl, user, pass);

        out.println("Connection successful!!!");

        myConn.close();

    } catch (Exception exc) {
        exc.printStackTrace();
    }
    }
}

Answer 1

您必须手动将jdbc_connector添加到tomcat服务器，您应该将jar包含到此文件夹$TOMCAT_HOME/lib

Answer 2

刚刚复制了你的bug。好像在新版本中驱动程序的名称已更改。当您下载maven依赖项时，最好采用最新的Stable版本 - 这样您就可以从社区获得更好，更快的支持。 `com.mysql.cj.jdbc.Driver” 这就是我得到的错误信息：

加载类com.mysql.jdbc.Driver'. This is deprecated. The new driver class is com.mysql.cj.jdbc.Driver'。驱动程序通过SPI自动注册，通常不需要手动加载驱动程序类。 com.mysql.cj.jdbc.exceptions.CommunicationsException：通信链接失败

java.lang.ClassNotFoundException：com.mysql.jdbc.Driver甚至在Intellij

2 个答案: