健壮的代码之JDBC示范

/** 注意：良好的编程习惯是尽量的写try-catch-finally
    * 而不是一味的throws Exception
    * 否则如果在一个大的方法体上写throws Exception，内部出现Exception时
    * 有可能导致程序停滞直到耗尽内存。
    */

import java.sql.*;


public class TestJDBC {


   public static void main(String[] args) {
      ResultSet rs = null;
      Statement stmt = null;
      Connection conn = null;
      try {//良好的编程习惯是尽量写try-catch-finally
         Class.forName("oracle.jdbc.driver.OracleDriver");
         //new oracle.jdbc.driver.OracleDriver();
         conn = DriverManager.getConnection("jdbc:oracle:thin:@192.168.0.1:1521:SXT", "scott", "tiger");
         stmt = conn.createStatement();
         rs = stmt.executeQuery("select * from dept");
         while(rs.next()) {
         System.out.println(rs.getString("deptno"));
         System.out.println(rs.getInt("deptno"));
         }
      } catch (ClassNotFoundException e) {
            e.printStackTrace();
      } catch (SQLException e) {
            e.printStackTrace();
      } finally {
           try {
                if(rs != null) {//在JDBC关闭过程中仍然有关闭异常需要捕捉
                    rs.close(); //首先判断某对象已被成功初始化，即!=null，然后关闭
                    rs = null;  //关闭后还需要将其设置回初始化的null值
                }
                if(stmt != null) {
                    stmt.close();
                    stmt = null;
                }
                if(conn != null) {
                    conn.close();
                    conn = null;
                }
            } catch (SQLException e) {
                    e.printStackTrace();
            }
       }
    }
}