DBConnection公共类的使用-------java操作数据库（3）

1.编写数据库连接属性jdbc-mysql.properties

username=root
password=123
url=jdbc:mysql://localhost:3306/makefriends
driverClassName=com.mysql.jdbc.Driver

2.编写DBConnection数据库公共操作类

package com.yun.utility;

import java.io.IOException;
import java.io.InputStream;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class DBConnection {
private static String user;
private static String password;
private static String url;
static {
try {
ClassLoader classLoader = DBConnection.class.getClassLoader();
// 数据库的配置文件路径
InputStream is = classLoader.getResourceAsStream("config/prop/jdbc-mysql.properties");
Properties props = new Properties();
props.load(is);
url = props.getProperty("url");
user = props.getProperty("username");
password = props.getProperty("password");
Class.forName(props.getProperty("driverClassName"));
} catch (ClassNotFoundException e) {
throw new RuntimeException("ClassNotFound");
} catch (IOException e) {
throw new RuntimeException("IO");
}
}

public static Connection getConnection() throws Exception {
return (Connection) DriverManager.getConnection(url, user, password);
}

public static Statement getStatement() throws SQLException{
return (Statement) DriverManager.getConnection(url, user, password).createStatement();
}

public static void close(ResultSet rs, Statement stat, Connection conn) throws Exception {
if (rs != null) {
rs.close();
}
if (stat != null) {
stat.close();
}
if (conn != null) {
conn.close();
}
}

public static void close(Statement stat, Connection conn) throws Exception {
if (stat != null) {
stat.close();
}
if (conn != null) {
conn.close();
}
}

}

3.编写测试类

package com.yun.test;

import java.sql.ResultSet;
import java.sql.SQLException;

import com.mysql.jdbc.Statement;
import com.yun.utility.DBConnection;

public class testDBConnection {
public static void main(String[] args) throws SQLException  {
Statement statement= DBConnection.getStatement();
String sql="select * from yunuser";
ResultSet rs=statement.executeQuery(sql);
while(rs.next())
{
System.out.println(rs.getString(2));
}
}

}