菜鸟找了一天一夜任然无法解决的问题

悬赏园豆：100 [已解决问题] 解决于 2017-11-06 09:40

向大神们求助

最近在学习Servlet做了一个简单的登录页面顺便练习了一下DBCP连接池 html 页面跳转到Servlet时控制台报 Cannot create JDBC driver of class '' for connect URL 'jdbc:mysql://localhost:3306/bookstore' 错误

org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'jdbc:mysql://localhost:3306/bookstore'
    at org.apache.commons.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452)
    at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
    at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
    at org.apache.commons.dbutils.AbstractQueryRunner.prepareConnection(AbstractQueryRunner.java:156)
    at org.apache.commons.dbutils.QueryRunner.query(QueryRunner.java:285)
    at com.study.servlet.LoginServlet.doGet(LoginServlet.java:43)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
    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:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    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:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
    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)
Caused by: java.sql.SQLException: No suitable driver
    at java.sql.DriverManager.getDriver(Unknown Source)
    at org.apache.commons.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1437)
    ... 29 more

1首先我先看了项目的 Libraries ，包导入了

2.以为是jar包版本问题又试了驱动 5.08 和5.1.39 版本的还是出现这个问题

3.为了验证代码问题我又把主要的三行代码放在了main方法中运行，居然没出错，还查出了sql结果集：main方法代码如下：

public static void main(String[] args) {
        DataSource dataSource=DBCPUtils.getDataSource();
        System.out.println(dataSource);
        QueryRunner qr=new QueryRunner(dataSource);
        //查询是否有改用户
        String userName="张三";
        String password="123456";
        String sql="select * from user where userName=? and password=?";
        Object [] params={userName,password};
        try {
             Object[] list = qr.query(sql, new ArrayHandler() , params);
             if (list!=null) {
                 //服务器行为
                 System.out.println("存在");
            }else {
                System.out.println("不存在");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

4我放弃了用DBCP 又试了C3P0连接池没有报错，SQL 语句正常执行

具体代码——以下

Servlet方法：

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //连接数据库，执行SQL语句
        //这里使用DBUtils操作数据库
        DataSource dataSource=DBCPUtils.getDataSource();
        System.out.println(dataSource);
        QueryRunner qr=new QueryRunner(dataSource);
        
        //创建输出流
        PrintWriter out=response.getWriter();
        request.setCharacterEncoding("utf-8");
        String userName=request.getParameter("userName");
        String password=request.getParameter("password");

        //查询是否有该用户
        String sql="select * from user where userName=? and password=?";
//        Object [] params={userName,password};
        try {
             User u = qr.query(sql,new BeanHandler<User>(User.class),userName,password);
             
         if (u!=null) {
                 //服务器行为
                request.getRequestDispatcher("/WEB13/html/Ok.html");
            }else {
                response.sendRedirect("/WEB13/html/No.html");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        
        
    }

DBCPUtils代码：

public class DBCPUtils {
    private static DataSource dataSource;
    private static Connection conn;
    static{
        
        try {
            InputStream is = DBCPUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties props=new Properties();
            props.load(is);
            dataSource=BasicDataSourceFactory.createDataSource(props);

        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }
    
    public static DataSource getDataSource(){
        return dataSource;
    }
    public static Connection getConnection(){
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        
    }
}

db.properties (src路径下)

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/bookstore
username=root
password=root

问了别人给我推荐了一个博客 http://blog.sina.com.cn/s/blog_e1235f680101fl9w.html

试了还是不行

DBCP连接池获取jdbc驱动

逆水行舟！ | 初学一级 | 园豆：54
提问于：2017-11-04 10:37

< >

最佳答案

BasicDataSourceFactory查找的配置文件中的数据库驱动字段应该是driverClassName

public class BasicDataSourceFactory implements ObjectFactory {

private final static String PROP_DRIVERCLASSNAME = "driverClassName";

收获园豆：100

faramita2016 | 菜鸟二级 |园豆：304 | 2017-11-05 11:15

大神看了你的建议我把db.properties 中的driver 改成了driverClassName 运行成功没有报错

我有个疑问就是配置文件的字段没有改动前把下面的三句代码放到main方法测试为什么没有出现org.apache.commons.dbcp.SQLNestedException 异常还能查出结果集

1 DataSource dataSource=DBCPUtils.getDataSource();
2 QueryRunner qr=new QueryRunner(dataSource);
3 Object[] list = qr.query(sql, new ArrayHandler() , params);

逆水行舟！ | 园豆：54 (初学一级) | 2017-11-06 09:33

@欢呀:

// Create a JDBC driver instance
Driver driver = null;
try {
if (driverFromCCL == null) {
driver = DriverManager.getDriver(url);
} else {
// Usage of DriverManager is not possible, as it does not
// respect the ContextClassLoader
driver = (Driver) driverFromCCL.newInstance();
if (!driver.acceptsURL(url)) {
throw new SQLException("No suitable driver", "08001");
}
}
}

这段代码的意思是可以根据连接串url找驱动，url中指定了mysql

faramita2016 | 园豆：304 (菜鸟二级) | 2017-11-07 09:09

@faramita2016: 谢谢。看了你发的代码，我果断看了BasicDataSource源代码，感觉受益匪浅。

逆水行舟！ | 园豆：54 (初学一级) | 2017-11-07 19:11

@欢呀: 客气，我也新手

faramita2016 | 园豆：304 (菜鸟二级) | 2017-11-08 16:43

清除回答草稿

您需要登录以后才能回答，未注册用户请先注册。

欢迎，请先 登录 或者 注册 。

菜鸟找了一天一夜任然无法解决的问题

欢迎，请先登录或者注册。