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  • jdbc初步（转）

    1. Jdbc的六个编程步骤

    1. 注册一个驱动

    注册驱动程序有三种方式：

    方式一：Class.forName(“oracle.jdbc.driver.OracleDriver”);

    JAVA 规范中明确规定：所有的驱动程序必须在静态初始化代码块中将驱动

    注册到驱动程序管理器中。

    方式二：Driver drv = new oracle.jdbc.driver.OracleDriver();

    DriverManager.registerDriver(drv);

    方式三：编译时在虚拟机中加载驱动

    javac –Djdbc.drivers = oracle.jdbc.driver.OracleDriver xxx.java

    java –D jdbc.drivers=驱动全名 类名

    使用系统属性名，加载驱动 -D 表示为系统属性赋值

    附 : mysql 的 Driver 的全名 com.mysql.jdbc.Driver

    SQLServer 的 Driver 的全名 com.microsoft.jdbc.sqlserver.SQLServerDriver

    2. 取得一个连接

    Conn = DriverManager.getConnection(jdbcURL,userName,password);

    3. 获得一个Statement声明对象

    Statement st = conn.createStatement();

    PreparedStatement ps = conn.prepareStatement(sql);

    CallableStatemetn cs = conn.prepareCall(sql);

    4. 通过Statement对象执行Sql语句

    sta.execute(String sql); 如果返回一个结果集则返回true,否则返回false。

    sta.executeQuery(String sql);返回一个查询结果集。

    sta.executeUpdate(String sql);返回值为 int 型，表示影响记录的条数。

    将 sql 语句通过连接发送到数据库中执行，以实现对数据库的操作。

    5. 若有结果集ResultSet则处理结果集

    ResultSetMetaDate rsmd = rs.getMetaData();

    int columnCount = rsmd.getColumnCount();

    While(rs.next()){

    for(int i = 1; i <= columnCount; i++)

    {

    if(i != 1) System.out.print(",");

    String name = rsmd.getColumnName(i); //取得第i列的列名称

    String value = rs.getString(i); //取得第i列的值

    System.out.print(name + "=" + value);

    }

    }

    6. 关闭资源

    2. 第一个Jdbc程序

    [java] view plaincopyprint?
    1. public class AccountDaoBad
    2. {
    3. public void select()
    4. {
    5. Connection con = null;
    6. Statement st = null;
    7. ResultSet rs = null;
    9. try
    10. {
    11. Class.forName("oracle.jdbc.driver.OracleDriver");
    12. /** static init block in OracleDriver*/
    13. String jdbcURL = “jdbc:oracle:thin:@192.168.0.5:1521:tarena”;
    14. con = DriverManager.getConnection(jdbcURL, "sd0703", "sd0703");
    15. st = con.createStatement();
    16. System.out.println(st.getFetchSize());
    17. String sql = "select id,no,owner,pwd,cdate,balance from sd0703_account";
    18. rs = st.executeQuery(sql);
    19. while(rs.next())
    20. {
    21. System.out.print("id=" + rs.getInt(1));
    22. System.out.print(",no=" + rs.getString(2));
    23. System.out.print(",owner=" + rs.getString(3));
    24. System.out.print(",pwd=" + rs.getString(4));
    25. System.out.print(",cdate=" + rs.getDate(5));
    26. System.out.println(",balance=" + rs.getDouble(6));
    27. }
    28. }catch(SQLException e)
    29. {
    30. e.printStackTrace();
    31. throw new RuntimeException(e.getMessage());
    33. }catch(ClassNotFoundException e)
    34. {
    35. e.printStackTrace();
    36. throw new RuntimeException(e.getMessege());
    38. }finally
    39. {
    40. try{ con.close();}catch(Exception e) {e.printStatckTrace();}
    41. }
    42. }
    public class AccountDaoBad
{
    public void select()
    {
        Connection con = null;
        Statement st = null;
        ResultSet rs = null;
        
        try
        {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            /** static init block in OracleDriver*/
String jdbcURL = “jdbc:oracle:thin:@192.168.0.5:1521:tarena”;
            con = DriverManager.getConnection(jdbcURL, "sd0703", "sd0703");
            st = con.createStatement();
            System.out.println(st.getFetchSize());
            String sql = "select id,no,owner,pwd,cdate,balance from sd0703_account";
            rs = st.executeQuery(sql);
            while(rs.next())
            {
                System.out.print("id=" + rs.getInt(1));
                System.out.print(",no=" + rs.getString(2));
                System.out.print(",owner=" + rs.getString(3));
                System.out.print(",pwd=" + rs.getString(4));
                System.out.print(",cdate=" + rs.getDate(5));
                System.out.println(",balance=" + rs.getDouble(6));
            }
        }catch(SQLException e)
        {
            e.printStackTrace();
            throw new RuntimeException(e.getMessage());
            
        }catch(ClassNotFoundException e)
        {
            e.printStackTrace();
            throw new RuntimeException(e.getMessege());
            
        }finally
        { 
            try{ con.close();}catch(Exception e) {e.printStatckTrace();}
        }        
    }



    3. 常用类

    1. Connection, Statement, ResultSet,

    4. 2.0新特性

    (1)事务管理与图片的存储

    [java] view plaincopyprint?
    1. public class ImageLibraryService
    2. {
    3. public void addImage(long id, String imageName, String path) throws SQLException
    4. {
    5. Connection con = null;
    6. PreparedStatement ps = null;
    7. ResultSet rs = null;
    8. try
    9. {
    10. con = ConnectionFactory.getConnection();
    11. con.setAutoCommit(false);
    12. String sql = "insert into ImageLibrary(id, name, image)";
    13. sql += " VALUES(?, ?, empty_blob())";
    14. ps = con.prepareStatement(sql);
    15. ps.setLong(1, id);
    16. ps.setString(2, imageName);
    17. ps.executeUpdate();
    18. ps.close();
    19. ps = con.prepareStatement("select image from ImageLibrary WHERE id = ? for update ");
    20. ps.setLong(1, id);
    21. rs = ps.executeQuery();
    22. if (rs.next())
    23. {
    24. Blob image = rs.getBlob(1);
    25. OutputStream out = image.setBinaryStream(0);
    26. BufferedOutputStream bufferedOut = new BufferedOutputStream(out);
    27. BufferedInputStream bufferedIn = new BufferedInputStream(new FileInputStream(path));
    28. int c;
    29. while ((c = bufferedIn.read()) != -1)
    30. {
    31. bufferedOut.write(c);
    32. }
    33. bufferedIn.close();
    34. bufferedOut.close();
    35. }
    36. con.commit();
    37. } catch (Exception e)
    38. {
    39. e.printStackTrace();
    40. try
    41. {
    42. con.rollback();
    43. } catch (SQLException se) { }
    44. throw new SQLException(e.getMessage());
    45. } finally
    46. {
    47. JdbcUtil.close(rs, ps, con);
    48. }
    49. }
    50. //以下代码没有进行细致的异常捕获
    51. public void restoreImage(long id, String filename) throws Exception
    52. {
    53. Connection con = ConnectionFactory.getConnection();
    54. Statement st = con.createStatement();
    55. String sql = "SELECT image From ImageLibrary Where id = " + id;
    56. ResultSet rs = st.executeQuery(sql);
    57. while (rs.next())
    58. {
    59. Blob image = rs.getBlob("image");
    60. BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(filename));
    61. BufferedInputStream in = new BufferedInputStream(image.getBinaryStream());
    62. int c;
    63. while ((c = in.read()) != -1) out.write(c);
    64. in.close();
    65. out.close();
    66. }
    67. }
    68. } 
    public class ImageLibraryService
{
    public void addImage(long id, String imageName, String path) throws SQLException
    {
        Connection con = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try
        {
            con = ConnectionFactory.getConnection();
            con.setAutoCommit(false);
            String sql = "insert into ImageLibrary(id, name, image)";
            sql += " VALUES(?, ?, empty_blob())";
            ps = con.prepareStatement(sql);
            ps.setLong(1, id);
            ps.setString(2, imageName);
            ps.executeUpdate();
            ps.close();
            ps = con.prepareStatement("select image from ImageLibrary WHERE id = ? for update ");
            ps.setLong(1, id);
            rs = ps.executeQuery();
            if (rs.next())
            {
                Blob image = rs.getBlob(1);
                OutputStream out = image.setBinaryStream(0);
                BufferedOutputStream bufferedOut = new BufferedOutputStream(out);
                BufferedInputStream bufferedIn = new BufferedInputStream(new FileInputStream(path));
                int c;
                while ((c = bufferedIn.read()) != -1)
                {
                    bufferedOut.write(c);
                }
                bufferedIn.close();
                bufferedOut.close();
            }
            con.commit();
        } catch (Exception e)
        {
            e.printStackTrace();
            try
            {
                con.rollback();
            } catch (SQLException se)  {    }
            throw new SQLException(e.getMessage());
        } finally
        {
            JdbcUtil.close(rs, ps, con);
        }
    }
//以下代码没有进行细致的异常捕获
    public void restoreImage(long id, String filename) throws  Exception
    {
        Connection con = ConnectionFactory.getConnection();
        Statement  st = con.createStatement();
String sql = "SELECT image  From ImageLibrary Where id = " + id;
        ResultSet rs = st.executeQuery(sql);
        while (rs.next())
        {
           Blob image = rs.getBlob("image");
           BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(filename));
            BufferedInputStream in = new BufferedInputStream(image.getBinaryStream());
           int c;
           while ((c = in.read()) != -1)   out.write(c);
           in.close();
           out.close();
        }
    }
}



    (2)结果集游标的上下游动

    [java] view plaincopyprint?
    1. con = ConnectionFactory.getConnection();
    2. st = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
    3. String sql = "select id,no,owner,pwd,cdate,balance from sd0703_account";
    4. rs = st.executeQuery(sql);
    5. rs.afterLast(); //将光标移动到此 ResultSet 对象的末尾，正好位于最后一行之后。
    6. while(rs.previous())
    7. {
    8. System.out.print("id=" + rs.getInt(1));
    9. System.out.print(",no=" + rs.getString(2));
    10. System.out.print(",owner=" + rs.getString(3));
    11. System.out.print(",pwd=" + rs.getString(4));
    12. System.out.print(",cdate=" + rs.getDate(5));
    13. System.out.println(",balance=" + rs.getDouble(6));
    14. } 
    con = ConnectionFactory.getConnection();
st = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
String sql = "select id,no,owner,pwd,cdate,balance from sd0703_account";
rs = st.executeQuery(sql);
rs.afterLast(); //将光标移动到此 ResultSet 对象的末尾，正好位于最后一行之后。       
while(rs.previous())
{
     System.out.print("id=" + rs.getInt(1));
     System.out.print(",no=" + rs.getString(2));
     System.out.print(",owner=" + rs.getString(3));
     System.out.print(",pwd=" + rs.getString(4));
     System.out.print(",cdate=" + rs.getDate(5));
     System.out.println(",balance=" + rs.getDouble(6));
}



    注：ResultSet静态常量字段(参见javax.sql.ResultSet)

    ResultSet.TYPE_SCROLL_INSENSITIVE

    该常量指示可滚动但通常不受 ResultSet 底层数据更改影响的 ResultSet 对象的类型。

    ResultSet.CONCUR_READ_ONLY

    该常量指示不可以更新的 ResultSet 对象的并发模式。

    http://www.cnblogs.com/smileallen/archive/2013/02/16/3391573.html
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  • 原文地址：https://www.cnblogs.com/softidea/p/4396931.html
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