运行项目时出现以下错误
我确保我的mysql用户名和密码正确，为什么会出现以下错误？
求大神指教！！！
警告: DbConnectionManager.getConnection() 获得数据库链接失败.
链接类型:com.mysql.jdbc.Driver
链接位置:jdbc:mysql://localhost:3306/db_librarySys?user=root&password=123456
源码：
package com.core;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
public class ConnDB {
public Connection conn = null;
public Statement stmt = null;
public ResultSet rs = null;
private static String propFileName = "/com/connDB.properties"; //指定资源文件保存的位置
private static Properties prop = new Properties();
private static String dbClassName ="com.mysql.jdbc.Driver";
private static String dbUrl =
"jdbc:mysql://localhost:3306/db_librarySys?user=root&password=123456";
public ConnDB(){
try {
InputStream in=getClass().getResourceAsStream(propFileName);
prop.load(in); //通过输入流对象加载Properties文件
dbClassName = prop.getProperty("DB_CLASS_NAME"); //获取数据库驱动
dbUrl = prop.getProperty("DB_URL",
"jdbc:mysql://localhost:3306/db_librarySys?user=root&password=123456");
}
catch (Exception e) {
e.printStackTrace(); //输出异常信息
}
}
public static Connection getConnection() {
Connection conn = null;
try {
Class.forName(dbClassName).newInstance();
conn = DriverManager.getConnection(dbUrl);
}
catch (Exception ee) {
ee.printStackTrace();
}
if (conn == null) {
System.err.println(
"警告: DbConnectionManager.getConnection() 获得数据库链接失败.\r\n\r\n链接类型:" +
dbClassName + "\r\n链接位置:" + dbUrl);
}
return conn;
}
/*
* 功能：执行查询语句
*/
public ResultSet executeQuery(String sql) {
try {
conn = getConnection();
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
rs = stmt.executeQuery(sql);
} catch (SQLException ex) {
System.err.println(ex.getMessage());
}
return rs;
}
/*
* 功能:执行更新操作
*/
public int executeUpdate(String sql) {
int result = 0;
try {
conn = getConnection(); //调用getConnection()方法构造Connection对象的一个实例conn
stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
result = stmt.executeUpdate(sql); //执行更新操作
} catch (SQLException ex) {
result = 0;
}
return result;
}
/*
* 功能:关闭数据库的连接
*/
public void close() {
try {
if (rs != null) {
rs.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (Exception e) {
e.printStackTrace(System.err);
}
}
}
