运行时错误:java.lang.ClassNotFoundException:com.mysql.jdbc.Driver

Question

我是mysql和jdbc的新手,我收到了这个标题中的错误.我一整天都在搜索,找不到适合我的解决方案.

我试过的:卸载/重新安装mysql,将mysql-connector-java-5.1.25-bin.jar和ojdbc7.jar粘贴到我试图运行的.class文件的相同位置,在不同的目录中重建程序,可能还有其他几件事.

我使用notepad ++进行编码,并使用windows命令提示符进行编译和运行.它编译得很好,但我试着运行

C:\ Projects\bin> java -cp.ClientBase

输出是:

java.lang.ClassnNotFoundException:com.mysql.jdbc.Driver

at java.net.URLClassloader $ 1.run(URLClassLoader.java:336)
at java.net.URLClassLoader $ 1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader .findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:432)
at sun.misc.Launcher $ AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass( ClassLoader.java:356)
在java.lang.Class.forName0(本机方法)
java.lang.Class.forName(Class.java:188)
在ClientBase.main(ClientBase.java:21)
再见.

// import packages
import java.sql.*;

// create class ClientBase
public class ClientBase{
            // JDBC driver name and database URL
            static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";                
            static final String DB_URL = "jdbc:mysql://localhost/CLIENTBASE";          



 // Database credentials
    static final String USER = "root";
    static final String PASS = "";

// Begin method main
public static void main(String[] args) {
    Connection conn = null;
    Statement stmt = null;

    try{
        // register JDBC driver
        Class.forName("com.mysql.jdbc.Driver");

        // Open connection
        System.out.println("Connecting to database...");
        conn = DriverManager.getConnection(DB_URL, USER, PASS);

        // Execute a query
        System.out.println("Creating statement...");
        stmt = conn.createStatement();
        String sql;
        sql = "SELECT id, name, address, address 2, city, phone, state, zip, fax FROM CLIENTBASE";
        ResultSet rs = stmt.executeQuery(sql);

        // Extract data from result set
        while(rs.next()){
            // Retrieve by column name
            int id = rs.getInt("id");
            String name = rs.getString("name");
            String address = rs.getString("address");
            String address2 = rs.getString("address2");
            String city = rs.getString("city");
            String phone = rs.getString("phone");
            String state = rs.getString("state");
            String zip = rs.getString("zip");
            String fax = rs.getString("fax");

            // Display values
            System.out.print("ID: " + id);
            System.out.print(" Name: " + name);
            System.out.println("Address:" + address);
            System.out.println(address2);
            System.out.print("City:" + city);
            System.out.print(" State: " + state);
            System.out.println(" Zip: " + zip);
            System.out.print("Phone: " + phone);
            System.out.println(" Fax: " + fax);
        } // end while

        // clean up
        rs.close();
        stmt.close();
        conn.close();
    }catch(SQLException se){
        // Handle errors for JDBC
        se.printStackTrace();
    }catch(Exception e){
        // Handle errors for Class.forName
        e.printStackTrace();
    }finally{
        // finally block used to close resources
        try{
            if(stmt!=null)
                stmt.close();
        }catch(SQLException se){
            se.printStackTrace();
        } // end finally
    } // end try
System.out.println("Goodbye.");
} // End method main
} // end class ClientBase

我还应该说,我将在这个代码的在线教程.它并不是他们如何拥有它,因为我决定制作一些与他们不同的东西,但它通常是相同的.我不认为这是一个代码问题,但错误是什么.

任何帮助,将不胜感激!我要疯了!

Answer 1

您需要将一个连接器库添加到Runtime类路径:

java -cp .;mysql-connector-java-5.1.25-bin.jar ClientBase

我的示例使用Windows类路径分隔符";",在其他系统上它可能不同(":"在Linux/Mac上).它还假设,它mysql-connector-java-5.1.25-bin.jar位于同一文件夹中.如果不是这样,那么将路径放到库而不是普通名称.

ClientBase 这里代表Java类文件名

c:\>javac Test.java
c:\>java -cp .;F:\CK\JavaTest\JDBCTutorial\mysql-connector-java-5.1.18-bin Test