Java Mysql：ClassNotFoundException ->找不到驱动程序

Question

可能的重复：
ClassNotFoundException com.mysql.jdbc.Driver

-connector -java-5.1.16-bin.jar 到我的 Eclipse 库中，此代码基于我在网上找到的教程，因为我以前没有在 Java 中使用过 MySQL。不幸的是，我没有看到我在哪里使用实际的 mysql-connector-java-5.1.16-bin.jar 并且控制台打印 Could not find driver. 意思是 抛出 ClassNotFoundException。您是否看到了我没有看到的（可能是显而易见的）问题？

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.sql.Timestamp;

public class MysqlConnector {

    private static MysqlConnector instance = null;
    private static Connection conn = null;

    private static String dbHost = "localhost";
    private static String dbPort = "3306";
    private static String database = "sample";
    private static String dbUser = "root";
    private static String dbPassword = "";

    public MysqlConnector() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://" + dbHost + ":"
                    + dbPort + "/" + database + "?" + "user=" + dbUser + "&"
                    + "password=" + dbPassword);
        } catch (ClassNotFoundException e) {
            System.out.println("Could not find driver."); //TODO LOGGER
        } catch (SQLException e) {
            System.out.println("Could not connect to database."); //TODO LOGGER
        }
    }

    public static MysqlConnector getInstance()
    {
        if(instance == null)
            instance = new MysqlConnector();
        return instance;
    }

    public boolean validateApiKey(String apikey)
    {
        if(conn != null)
        {
            Statement query;
            try {
                query = conn.createStatement();

                String sql = "SELECT startdate, expiration, active " + "FROM apikeys "
                        + "WHERE apikey = '" + apikey +"'";
                ResultSet result = query.executeQuery(sql);

                if(result.getFetchSize()>0 && result.getInt("active")==1){
                    Date now = new Date();
                    Date startdate = result.getDate("startdate");
                    Date expirationdate = result.getDate("expiration");
                    if(now.before(expirationdate) && now.after(startdate)){
                        return true;
                    } else {
                        return false;
                    }
                } else {
                    return true;
                }
            } catch (SQLException e) {
                e.printStackTrace();
                return false;
            }
        }
        return false;
    }

}

Answer 1

右键单击您的项目>构建路径>添加库并添加 jar 文件。

还要确保它位于您的运行时路径上。 右键单击主类>运行为>运行配置>类路径

Answer 2

我唯一看到的是，您需要在项目中添加 MySQL Connector 的库，而不仅仅是在 Eclipse 库中。

Answer 3

你怎么运行这个？

时，您会从该 jar 实例化一个类

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

当您执行http://download.oracle.com/javase/1.4.2/docs/api/java/lang/Class.html#forName%28java.lang.String%29