代码有什么问题在调试的时候有很多错误。我正在编写一个单例类的代码来连接数据库mysql。
以下是我的代码
package com.glomindz.mercuri.util;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
public class MySingleTon {
String url = "jdbc:mysql://localhost:3306/";
String dbName = "test";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "";
private static MySingleTon myObj;
private Connection Con ;
private MySingleTon() {
System.out.println("Hello");
Con= createConnection();
}
@SuppressWarnings("rawtypes")
public Connection createConnection() {
Connection connection = null;
try {
// Load the JDBC driver
Class driver_class = Class.forName(driver);
Driver driver = (Driver) driver_class.newInstance();
DriverManager.registerDriver(driver);
connection = DriverManager.getConnection(url + dbName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
}
return connection;
}
/**
* Create a static method to get instance.
*/
public static MySingleTon getInstance() {
if (myObj == null) {
myObj = new MySingleTon();
}
return myObj;
}
public static void main(String a[]) {
MySingleTon st = MySingleTon.getInstance();
}
}
我是java的新手。请帮帮忙。
发布于 2013-07-05 18:56:53
如果在IDE中出现错误(编译时错误),则需要将mysql连接器jar文件添加到库中,并将其添加到项目的引用库中。
如果您在运行它时出现此错误,则可能是因为您没有将mysql-connector JAR文件包含到lib服务器的lib文件夹中。
将mysql-connector-java-5.1.25-bin.jar
添加到类路径和lib服务器的lib目录中。Tomcat库路径以Tomcat 6.0\lib
为例给出
发布于 2015-03-11 21:28:22
对于Gradle-based项目,您需要依赖于MySQL Java Connector
dependencies {
compile 'mysql:mysql-connector-java:6.0.+'
}
发布于 2013-07-05 16:51:57
检查类路径download from here中的jar(mysql-connector-java-bin)
https://stackoverflow.com/questions/17484764
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