java数据库，出现java.lang.ClassNotFoundException 问题

Question

package S;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;

public class JDBCS {
String url = "jdbc:mysql://localhost:3307/ty10";
String name = "root";
String password = "mysql";
Connection conn = null;
PreparedStatement pps=null;
ResultSet rs = null;

JDBCS() {
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection(url,name,password);
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

void update(String sql,String[] val){

    try {

        pps = conn.prepareStatement(sql);

        for (int i = 0; val!=null && i < val.length; i++) {
            pps.setString(i+1, val[i]);
        }

        pps.executeUpdate();

    }catch (SQLException e) {
        e.printStackTrace();
    }
}

ArrayList> queryToList(String sql ,String[] val){

rs=query(sql,val);

ArrayList<HashMap<String ,String>> list = new ArrayList<HashMap<String,String>>();

try {
    ResultSetMetaData mt = rs.getMetaData();//结果集结构对象（有啥字段，类型，长度。。。）

    while(rs.next()){
        HashMap<String ,String> map = new HashMap<String ,String>();

        for (int i = 0; i < mt.getColumnCount(); i++) {//取所有字段

            String name = mt.getColumnName( i+1 );//获取列名
            map.put(name, rs.getString(name));

        }

        list.add(map);
    }
} catch (SQLException e) {
    e.printStackTrace();
}


return list ;

}

ResultSet query(String sql ,String[] val){

try {

    pps = conn.prepareStatement(sql);

    for (int i = 0; val!=null && i < val.length; i++) {
        pps.setString(i+1, val[i]);
    }

    rs = pps.executeQuery();
    return rs ;
}catch (SQLException e) {
    e.printStackTrace();
}
return null;

}
void close(){

try {
    rs.close();
} catch (SQLException e2) {
    e2.printStackTrace();
}

try {
    pps.close();
} catch (SQLException e1) {
    e1.printStackTrace();
}

try {
    conn.close();
} catch (SQLException e) {
    e.printStackTrace();
}

}
}
运行后错误提示
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at S.JDBCS.(JDBCS.java:22)
at S.student2.main(student2.java:9)
Exception in thread "main" java.lang.NullPointerException
at S.JDBCS.query(JDBCS.java:81)
at S.student2.main(student2.java:10)

Answer 1

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
很清楚，你的jdbc驱动类没有