Question

这是我的DAO：

package be.pxl.ticket.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Date;

import be.pxl.ticket.bean.TicketBean;

public class TicketDAO {
    private String url;
    private String user;
    private String password;

public TicketDAO(String url, String user, String password) {
    this.url = url;
    this.user = user;
    this.password = password;
}

public void setDriver(String driver)
         throws ClassNotFoundException {
      // Laad de driver
       Class.forName(driver);
   }

public TicketBean getTicketById(int id) {
    if (id > 0) {
        try (Connection con = getConnection();
                PreparedStatement stmt = con.prepareStatement(
                        "SELECT id, state, location, description, title, timeCreated, submitBy, assignedTo from tickettable WHERE id=?")) {
            stmt.setInt(1, id);
            try (ResultSet rs = stmt.executeQuery()) {
                if (rs.next()) {
                    TicketBean ticket = new TicketBean();
                    ticket.setId(id);
                    ticket.setState(rs.getString("state"));
                    ticket.setLocation(rs.getString("location"));
                    ticket.setDescription(rs.getString("description"));
                    ticket.setTitle(rs.getString("title"));
                    ticket.setTimeCreated(rs.getDate("timeCreated"));
                    ticket.setSubmitBy(rs.getString("submitBy"));
                    ticket.setAssignedTo(rs.getString("assignedTo"));
                    return ticket;
                } else {
                    return null;// als ticket niet wordt gevonden
                }
            } catch (SQLException e) {
                e.printStackTrace();
                System.out.println("Failed to get Ticket");
                return null;
            }
        } catch (SQLException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
            System.out.println("Failed to get Ticket 2");
            return null;
        }
    } else {
        System.out.println("Id must be greater than 0");
        return null;
    }
}

private Connection getConnection() throws SQLException {
       return DriverManager.getConnection(url, user, password);
}

public void setUrl(String url) {
    this.url = url;
}

public void setUser(String user) {
    this.user = user;
}

public void setPassword(String password) {
    this.password = password;
}

}

这是我的servlet：

package be.pxl.ticket.servlet;

import java.io.IOException;

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 be.pxl.ticket.bean.TicketBean;
import be.pxl.ticket.dao.TicketDAO;
import be.pxl.ticket.service.ITicketService;
import be.pxl.ticket.service.TicketService;

@WebServlet("/Ticket")
public class TicketServlet extends HttpServlet {
    private ITicketService service;

    public void init() throws ServletException{
        super.init();
        service = new TicketService();
        service.setTicketDAO(new TicketDAO("mysql.jdbc://localhost/ticketdb1","root",""));
    }

    public void doGet(HttpServletRequest req, HttpServletResponse res) {
        int id = Integer.parseInt(req.getParameter("id"));
        TicketBean ticket = service.getTicketById(id);
        System.out.println(id);
        req.setAttribute("tb", ticket);
        try {
            req.getRequestDispatcher("TicketView.jsp").forward(req, res);//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        } catch (ServletException e) {
            System.out.println("servlet-exception :0");
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("something wrong with IO");
            e.printStackTrace();
        }

        System.out.println("triggered doGet");
    }

    public void doPost(HttpServletRequest req, HttpServletResponse res) {
        System.out.println("triggered doPost");
    }

}

这是我的服务：

package be.pxl.ticket.service;

import java.sql.SQLException;

import be.pxl.ticket.bean.TicketBean;
import be.pxl.ticket.dao.TicketDAO;

public class TicketService implements ITicketService {
    private TicketDAO ticketDAO;

    @Override
    public TicketBean getTicketById(int id){
        // TODO Auto-generated method stub
            return ticketDAO.getTicketById(id);

    }

    public TicketDAO getTicketDAO() {
        return ticketDAO;
    }

    public void setTicketDAO(TicketDAO ticketDAO) {
        this.ticketDAO = ticketDAO;
    }

}

错误消息是：

java.sql.SQLException: No suitable driver found for mysql.jdbc://localhost/ticketdb1
Failed to get Ticket 2
1
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at be.pxl.ticket.dao.TicketDAO.getConnection(TicketDAO.java:68)
    at be.pxl.ticket.dao.TicketDAO.getTicketById(TicketDAO.java:31)
    at be.pxl.ticket.service.TicketService.getTicketById(TicketService.java:14)
    at be.pxl.ticket.servlet.TicketServlet.doGet(TicketServlet.java:28)
    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:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    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:141)
    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:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1502)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1458)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
triggered doGet

我不知道这里有什么问题。我的库和mysql.jar

中有jstl.jar

它与驱动程序说了些什么，但它的设置如此

Answer 1

连接服务器时检查线路

service.setTicketDAO(new TicketDAO("mysql.jdbc://localhost/ticketdb1","root",""));

应该是

service.setTicketDAO(new TicketDAO("jdbc:mysql://localhost:3306/ticketdb1","root",""));

检查数据库网址，我更改了它。

这里3306是默认的mysql端口号更改，如果你的情况不同。

此外，您还必须使用

加载mysql连接器的驱动程序

Class.forName("com.mysql.jdbc.Driver");

并且需要包含mysql-connector.jar文件。

希望它能提供帮助。

Answer 2

以下是您的网址问题

service.setTicketDAO(new TicketDAO("mysql.jdbc://localhost/ticketdb1","root",""))

试试这个jdbc:mysql://localhost/dbname而不是jdbc.mysql://localhost/dbname

编辑：1

尝试将driver jar放在服务器lib文件夹中。 ($CATALINA_HOME/lib)

我认为甚至在实例化应用程序之前就需要设置连接池。

Answer 3

JDBC JAR属于Tomcat / lib文件夹。从这些docs：

这意味着只有监听器可见的库，例如那些在$ CATALINA_BASE / lib中将扫描数据库驱动程序。

您的数据库网址也是错误的。再看一下docs。您的网址是：

mysql.jdbc://localhost/ticketdb1

应该是：

jdbc:mysql://localhost/ticketdb1

您没有为您的应用程序使用root访问权限，是吗？这是懒惰和危险的。为您的应用创建新用户并授予适当的权限。

此类连接到在我的机器上运行的MySQL。它提供了一些有用的消息，你会发现它们很有帮助。记下JAR版本和驱动程序类名称。

package database;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
 * Database utilities
 * Created by Michael
 * Creation date 5/3/2016.
 * @link https://stackoverflow.com/questions/36999860/mysql-driver-problems/37000276#comment61553720_37000276
 */
public class DatabaseUtils {

    public static final String DEFAULT_DRIVER = "com.mysql.cj.jdbc.Driver";
    public static final String DEFAULT_URL = "jdbc:mysql://localhost/world";
    public static final String DEFAULT_USERNAME = "root";
    public static final String DEFAULT_PASSWORD = "xxx";

    public static void main(String[] args) {
        Connection connection = null;
        try (connection = createConnection(DEFAULT_DRIVER, DEFAULT_URL, DEFAULT_USERNAME, DEFAULT_PASSWORD)) {
            DatabaseMetaData meta = connection.getMetaData();
            System.out.println(String.format("Connected to %s version %s", meta.getDatabaseProductName(), meta.getDatabaseProductVersion()));
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
    }

    public static Connection createConnection(String driverClass, String url, String username, String password) throws ClassNotFoundException, SQLException {
        Class.forName(driverClass);
        return DriverManager.getConnection(url, username, password);
    }

    public static void close(Connection connection) {
        try {
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

我在我的pom.xml中使用JDK 8和这种依赖：

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>6.0.2</version>
    </dependency>

这是我得到的输出：

Tue May 03 05:48:30 EDT 2016 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
Connected to MySQL version 5.7.11-log

Mysql驱动问题

3 个答案:

编辑：1