Java, JDBC connection to the database by loading the configuration file properties

　　Normally, when we connect to the database via JDBC, the database will not write configuration death, because then there is a database change, it is necessary to repackage deployed to the server or replace the associated .class files, so very inflexible. Therefore, we would typically load the database configuration by reading configuration file way, only this time to change the configuration file can be friends, very convenient.

　　

　　Directly on the code, here is the java file:

. 1  public  class SyncDataFn {
 2      
. 3      Private  static String Driver;
 . 4      Private  static String URL;
 . 5      Private  static String username;
 . 6      Private  static String password;
 . 7      
. 8      static {
 . 9          the try {
 10              // 1. Get the current class by class loader 
11              . classLoader = SyncDataFn ClassLoader class .getClassLoader ();
 12 is              // 2. methods of obtaining a class loader input stream 
13             = ClassLoader.getResourceAsStream in the InputStream ( "../ config / jdbc-interface.properties" );
 14              // 3. Create a properties object 
15              the Properties The props = new new the Properties ();
 16              // 4. Load the input stream 
. 17              The props. Load (in);
 18 is              // 5. the acquired for the relevant parameters 
. 19              Driver = props.getProperty ( "driverClassName" );
 20 is              URL = props.getProperty ( "URL" );
 21 is              username = props.getProperty ( "username" ) ;
 22 is              password = props.getProperty ( "password" );
 23 is         } catch (IOException e) {
24             e.printStackTrace();
25         }
26  
27     }
28     
29     public int jxJson() throws Exception {
30         // 创建Statement用于执行SQL语句
31         Statement stmt = null;
32         String strSQL = "";
33         Connection connection = null;
34         
35         try {
36             Class.forName(driver);
37             connection = DriverManager.getConnection(url, username, password);
38         } catch (ClassNotFoundException e) {
39             e.printStackTrace();
40         } catch (SQLException e) {
41             e.printStackTrace();
42         }
43     }
44 }

　　

　　Here is the properties file:

1 driverClassName=oracle.jdbc.OracleDriver
2 url=jdbc:oracle:thin:@172.16.35.35:1521:ecard
3 username=ecard
4 password=ecard

　　

　　There is a pit call classLoader.getResourceAsStream () Gets properties file path when the page get less than the beginning of how, later asked the degree of your mother know that his path is based on the start of .class.

　　Summary: If you want to get the configuration file, you have to generate the final .class file for the start point, not the path .java file as a starting point, as is the use of real .class file.