[J2EE] 有关 PreparedStatement

 1 import java.sql.Connection;
 2 import java.sql.DriverManager;
 3 import java.sql.PreparedStatement;
 4 import java.sql.SQLException;
 5 
 6 import oracle.jdbc.OracleConnection;
 7 
 8 
 9 public class Test
10 {
11      static Connection con = null;
12     public static void main(String args[]) throws ClassNotFoundException, SQLException 
13     {
14         con = ((oracle.jdbc.OracleConnection)getConnection());
15         PreparedStatement ps0 = getPS(con);
16         ps0.close();
17         PreparedStatement ps1 = getPS(con);
18         ps1.close();
19         System.out.println(ps0==ps1);//如果是true，说明cache发生了作用
20         
21         
22         con.close();
23         con = null;
24         con = ((oracle.jdbc.OracleConnection)getConnection());
25         PreparedStatement ps2 = getPS(con);
26         ps2.close();
27         con.close();
28         System.out.println(ps1==ps2);//如果是false，说明connection关闭后，会重新缓存
29     
30     }
31     
32     //获取PS实例
33     public static PreparedStatement getPS(Connection con)throws ClassNotFoundException, SQLException{
34           
35            String sql = "select * from cms_turbine t where t.mapping like ?";
36            PreparedStatement ps1 = con.prepareStatement(sql);
37            ps1.setString(1, "hello");
38           return ps1;
39     }
40     
41     //建立连接
42     public static Connection getConnection(){
43         if(con == null){
44         try{
45             Class.forName("oracle.jdbc.driver.OracleDriver");
46             con = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1523:XXX",xx,xx);
47 
48 //下面两句是为了开启cache
49             ((oracle.jdbc.OracleConnection)con).setImplicitCachingEnabled(true);
50             ((oracle.jdbc.OracleConnection)con).setStatementCacheSize(10);
51        }catch(Exception e){
52            e.printStackTrace();
53        }
54         }
55         return con;
56     }
57 }