Java数据库连接技术(JDBC)

一.准备创建数据库

1.创建数据库
drop database if exists jt_db;
create database jt_db charset utf8;
    use jt_db;
    create table account(
    id int primary key auto_increment,
    name varchar(50),
    money double
);
insert into account values(null, 'jack', 1000);
insert into account values(null, 'tom', 800);
insert into account values(null, 'mini', 900);

通过select * from account; 语句在cmd窗口查询

二.测试
1.创建一个可以获取连接并且可以释放资源的类

public class JdbcUtil {
	public static Connection getCon() {
		Connection conn=null;
		try {
			//1.注册驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接
			 conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/jt_db?characterEncoding=utf-8", 
					"root", "root");
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
	}
	
	public static Connection getCon(String db,String user,String password) {
		
		Connection conn=null;
		try {
			//1.注册驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接
			 conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/"+db+"?characterEncoding=utf-8", 
					 user, password);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
		
	}
	
	public static void close(ResultSet re,Statement statement,Connection conn) {
		if(re!=null) {
			try {
				re.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				re=null;
			}
		}
		if(statement!=null) {
			try {
				statement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				statement=null;
			}
		}
		if(conn!=null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				conn=null;
			}
		}
	}
}

3.通过JDBC技术查询

public class TestJdbc {

	public static void main(String[] args) {
		Connection conn=null;
		Statement statement=null;
		ResultSet re=null;
		try {
			//1.注册驱动并且获取连接
			 conn = JdbcUtil.getCon();
			//2.mysql语句
			String sql="select * from account";
			//3.获取传输器
			statement = conn.createStatement();
			//4.通过传输器发送mysql语句
			 re = statement.executeQuery(sql);
			//5.打印结果
			while(re.next()) {
				int id=re.getInt("id");
				String name=re.getString("name");
				String money=re.getString("money");
				System.out.println(id+" : "+name+" : "+money);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			//6.释放资源
			JdbcUtil.close(re, statement, conn);
		}
		

	}

}