Jdbc总结

CallableStatement

public static void main(String[] args) {

    Connection conn = DBConn.connOracle();

    CallableStatement cs = conn.prepareCall("{call p(?,?,?,?)}");

    cs.registerOutParameter(3, Types.INTEGER);

    cs.registerOutParameter(4, Types.INTEGER);

    cs.setInt(1, 20);

    cs.setInt(2, 30);

    cs.setInt(4, 40);

    cs.execute();

    System.out.println(cs.getInt(3));

    System.out.println(cs.getInt(4));

    cs.close();

    conn.close();

}

获取游标参数

public static void main(String[] args) throws Exception{

    Connection conn = DBUtil.getConn();

    //PreparedStatement--->Statement

    CallableStatement cs = conn.prepareCall("{call p_curosr (?)}");

    cs.registerOutParameter(1, OracleTypes.CURSOR);

    cs.execute();

    ResultSet rs = ((OracleCallableStatement)cs).getCursor(1);

    while(rs.next()){

       System.out.println(rs.getInt(1)+"====="+rs.getString(2));

    }  

}

Batch

public static void main(String[] args) {

       Connection conn = DBConn.connOracle();

       /*

       Statement stmt = conn.createStatement();

       stmt.addBatch("insert into dept2 values(51,'500','haha')");

       stmt.addBatch("insert into dept2 values(52,'500','haha')");

       stmt.addBatch("insert into dept2 values(53,'500','haha')");

       stmt.executeBatch();

       stmt.close();

       */

       PreparedStatement ps = conn.prepareStatement("insert into dept2 values(?,?)");

       ps.setInt(1, 61);

       ps.setString(2, "haha");

       ps.addBatch();

      

       ps.setInt(1, 62);

       ps.setString(2, "hehe");

       ps.addBatch();   

      

       ps.executeBatch();

       ps.close();

       conn.close();

    }

读取数据库配置文件

public class DBUtil {

    private static Properties properties = null; 

    static{

       //InputStream is = DBUtil.class.getResourceAsStream("db.properties");

       //InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream("db.properties");

       //若是位于包下面的资源，则能够：

       InputStream is = Thread.currentThread().getContextClassLoader().getResourceAsStream("com/kingdom/db.properties");

       properties = new Properties();

       try {

           properties.load(is);

           Class.forName(properties.getProperty("driver"));

           String url = properties.getProperty("url");

           String user = properties.getProperty("user");

           String pwd = properties.getProperty("pwd");

       } catch (IOException e) {

           e.printStackTrace();

       } catch (ClassNotFoundException e) {

           e.printStackTrace();

       }     

    }

}

最小化链接池

public class DBConnPool {

    private static List<Connection> pool;

    private static final int POOL_MAX_SIZE = 100;

    private static final int POOL_MIN_SIZE = 50;

    private static String url;

    private static String user;

    private static String pwd;

   

    static {

       InputStream is = DBConnPool.class.getClassLoader().getResourceAsStream("db.properties");

       Properties prop = new Properties();

       try {

           prop.load(is);

           Class.forName(prop.getProperty("jdbcDriver"));

           url = prop.getProperty("url");

           user = prop.getProperty("user");

           pwd = prop.getProperty("pwd");

           is.close();

       } catch (IOException e) {

           e.printStackTrace();

       } catch (ClassNotFoundException e) {

           e.printStackTrace();

       }

       initPool();

    }

   

    /**

     * 获取数据库链接池，若是当前池中有可用链接，则将池中最后一个返回(并从池中remove该链接，表示

     * 正在使用，用完后再放回池中)，若是没，则新建一个返回。

     */

    public synchronized static Connection getConnection(){

       Connection conn = null;

       if (pool==null) {

           pool = new ArrayList<Connection>();

       }

       if (pool.isEmpty()) {

           conn = createConnection();

       } else {

           int lastIndex = pool.size()-1;

           conn = pool.get(lastIndex);

           pool.remove(lastIndex);

       }

       return conn;

    }

   

    /**

     * 将使用完毕的链接放回链接池中，判断当前池中的链接数是否已经超过最大值，若是超过，则关闭该链接，

     * 若是不超，则放回池中以备下次使用。

     */

    public synchronized static void closeConnection(Connection conn){

       if (pool.size()>POOL_MAX_SIZE) {

           try {

              conn.close();

           } catch (SQLException e) {

              e.printStackTrace();

           }

       } else {

           pool.add(conn);

       }

    }

 

    /**

     * 获得链接

     */

    private static Connection createConnection() {

       Connection conn = null;

       try {

           conn = DriverManager.getConnection(url,user,pwd);

       } catch (SQLException e) {

           e.printStackTrace();

       }

       return conn;

    }

   

    /**

     * 初始化链接池

     */

    private static void initPool() {

       if (pool==null) {

           pool = new ArrayList<Connection>();

       }

       while (pool.size()<POOL_MIN_SIZE) {

           pool.add(createConnection());

           System.out.println(pool.size());

       }

    }  

}