jdbc 新认识

Posted 2020-08-14 liouwei4083

以前一直用jdbc，没有深入看看，原来jdbc是java自己的接口规范，db厂商按照接口进行开发对应的驱动，jdbc可以获取db中的元信息，执行sql，获取结果，操作db等等。示例如下。

public static void main(String[] args) {
        try {
            Class.forName("oracle.jdbc.OracleDriver");
            Connection con = DriverManager.getConnection("jdbc:Oracle:thin:DEVH3IMAGE/[email protected]//localhost:1521/orcl");
            
            //获取数据库元信息
            DatabaseMetaData data = con.getMetaData();
            System.out.println("数据库db名称："+data.getDatabaseProductName());
            System.out.println("数据库db版本"+data.getDatabaseProductVersion());
            System.out.println("链接驱动名称："+data.getDriverName());
            System.out.println("db链接url信息："+data.getURL());
            
            //获取db所有表名称
            ResultSet tableset =  data.getTables("orcl", "DEVH3IMAGE", null, new String[]{"TABLE"});
            System.out.println("db中所有表名");
            while (tableset.next()) {
                System.out.print(tableset.getString("TABLE_NAME") + "\t");
            }
            System.out.println();
            ResultSet colset =  data.getColumns("orcl", "DEVH3IMAGE", "T_YX_01",null);
            System.out.println("表T_YX_01中的所有列名");
            while (colset.next()) {
                System.out.print(colset.getString("COLUMN_NAME") + "\t");
            }
            System.out.println();
            //同样的 可以获取到db中所有的索引 存储过程 等等信息
            
            System.out.println("=====================================");
            
            //设置只读
//            con.setReadOnly(true);
            System.out.println("con is read only ? == "+con.isReadOnly());
            //默认是自动提交事务
            System.out.println("con is auto commit?==="+con.getAutoCommit());
            System.out.println("=====================================");
            
            //普通查询
            Statement st = con.createStatement();
            ResultSet set = st.executeQuery("select * from t_yx_01");
            st.close();
            
            //带参数查询
            PreparedStatement pst = con.prepareStatement("select * from t_yx_01 where id = ?");
            pst.setString(1, "1930128");
            ResultSet prSet = pst.executeQuery();
            ResultSetMetaData rdata =  prSet.getMetaData();
            while (prSet.next()) {
                for (int i = 1; i <= rdata.getColumnCount(); i++) {
                    System.out.print(rdata.getColumnName(i) +":"+ prSet.getString(rdata.getColumnName(i)));
                    System.out.print("\t");
                }
                System.out.println();
            }
            pst.close();
            
            System.out.println("=====================================");
            con.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            //sqlexception中有sql自己的异常信息
            System.out.println(e.getErrorCode());
            System.out.println(e.getMessage());
            System.out.println(e.getSQLState());
            e.printStackTrace();
        }