获取数据库连接

-------------------------------oracle--------------------------------
驱动：oracle.jdbc.driver.OracleDriver

url：jdbc:oracle:thin:@host:port:dbname 例：jdbc:oracle:thin:@192.168.1.110:1521:dbOracle

port：端口号，默认是1521

---------------------------sql server---------------------------------
驱动：com.microsoft.jdbc.sqlserver.SQLServerDriver

url：jdbc:microsoft:sqlserver://host:port;databasename=dbname 例：jdbc:sqlserver://192.168.1.111:1433;databasename=dbSql

port：端口号，默认是1433

-------------------------------mysql--------------------------------
驱动：org.gjt.mm.mysql.Driver或com.mysql.jdbc.Driver

url：jdbc:mysql://host:port/dbname   例：jdbc:mysql://192.168.1.112:3306/dbMysql

port：端口号，默认3306

    @Test
    public void testOracle(){
        String driverurl = "jdbc:oracle:thin:@192.168.1.110:1521:dbOracle";
        String user = "user";
        String password = "password";
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            conn = DriverManager.getConnection(driverurl, user, password);
            String sql = "select * from tab_user";
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
            while(rs.next()){
                System.out.print(rs.getInt("userid"));
                System.out.print(" ;"+rs.getString("username"));
                System.out.println();
            }
        } catch (ClassNotFoundException e) {
            System.out.println("未找到类");
            e.printStackTrace();
        } catch (SQLException e) {
            System.out.println("获取连接失败");
            e.printStackTrace();
        }finally{
            try {
                if(rs != null) rs.close();
                if(stmt != null) stmt.close();
                if(conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }