driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/数据库名
username=root
password=123456
JDBCUtil.java
/**
* JDBC工具类
* @Author: fangju
* @Date: 2019/6/15
*/
public class JDBCUtil {
private static String driver;
private static String url;
private static String username;
private static String password;
//静态代码块,在程序编译的时候执行
static {
try {
//创建Properties对象
Properties p = new Properties();
//获取文件输入流
InputStream in = new FileInputStream("db.properties");
//加载输入流
p.load(in);
//获取数据库连接驱动名字
driver = p.getProperty("driverClassName",null);
//获取数据库连接地址
url = p.getProperty("url",null);
//获取数据库连接用户名
username = p.getProperty("username",null);
//获取数据库连接密码
password = p.getProperty("password",null);
if(driver != null && url != null
&& username != null && password != null){
//加载驱动
Class.forName(driver);
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取连接对象
* @return Connection连接对象
*/
public static Connection getConnection(){
Connection conn = null;
try {
conn = DriverManager.getConnection(url,username,password);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
/**
* 关闭连接(Connection连接对象必须在最后关闭)
* @param conn Connection连接对象
* @param st 编译执行对象
* @param rs 结果集
*/
public static void close(Connection conn, Statement st, ResultSet rs){
try {
if(rs != null){
rs.close();
}
if(st != null){
st.close();
}
if(conn != null){
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}