Java Annotation(Java 注解)

 1 /**
 2  * 
 3  */
 4 package com.b510.hongten.annotation;
 5 
 6 import java.lang.annotation.Documented;
 7 import java.lang.annotation.ElementType;
 8 import java.lang.annotation.Retention;
 9 import java.lang.annotation.RetentionPolicy;
10 import java.lang.annotation.Target;
11 
12 /**
13  * JDBC annotation
14  * 
15  * @author Hongten
16  * @date 2013-4-10
17  */
18 @Documented
19 @Retention(RetentionPolicy.RUNTIME)
20 @Target(ElementType.TYPE)
21 public @interface JDBCAnnotation {
22 
23     String driver() default "com.mysql.jdbc.Driver";
24 
25     String dbName() default "";
26 
27     String encoding() default "UTF-8";
28 
29     String port() default "3306";
30 
31     String host() default "localhost";
32 
33     String userName() default "root";
34 
35     String password() default "";
36 
37 }

  1 /**
  2  * 
  3  */
  4 package com.b510.hongten.jdbc;
  5 
  6 import com.b510.hongten.annotation.JDBCAnnotation;
  7 
  8 /**
  9  * @author Hongten
 10  * @date 2013-4-12
 11  */
 12 @JDBCAnnotation(dbName = "db_lucene", port = "3306", host = "192.168.0.119", userName = "root", password = "root")
 13 public class JDBCUtil {
 14 
 15     private static String driver;
 16     private static String dbName;
 17     private static String encoding;
 18     private static String port;
 19     private static String host;
 20     private static String passwrod;
 21     private static String userName;
 22     private static String url;
 23 
 24     public void checkInterceptor(Class<?> cl) throws Exception {
 25         boolean flag = cl.isAnnotationPresent(JDBCAnnotation.class);
 26         if (flag) {
 27             JDBCAnnotation jdbcAnnotation = cl.getAnnotation(JDBCAnnotation.class);
 28             driver = jdbcAnnotation.driver();
 29             dbName = jdbcAnnotation.dbName();
 30             encoding = jdbcAnnotation.encoding();
 31             port = jdbcAnnotation.port();
 32             host = jdbcAnnotation.host();
 33             userName = jdbcAnnotation.userName();
 34             passwrod = jdbcAnnotation.password();
 35             url = "jdbc:mysql://" + host + ":" + port + "/" + dbName + "?characterEncoding=" + encoding;
 36             System.out.println("JDBCUtil加载注释完成...");
 37         }
 38     }
 39 
 40     public JDBCUtil() {
 41         try {
 42             checkInterceptor(JDBCUtil.class);
 43         } catch (Exception e) {
 44             e.printStackTrace();
 45         }
 46     }
 47 
 48     public static String getDriver() {
 49         return driver;
 50     }
 51 
 52     public static void setDriver(String driver) {
 53         JDBCUtil.driver = driver;
 54     }
 55 
 56     public static String getDbName() {
 57         return dbName;
 58     }
 59 
 60     public static void setDbName(String dbName) {
 61         JDBCUtil.dbName = dbName;
 62     }
 63 
 64     public static String getEncoding() {
 65         return encoding;
 66     }
 67 
 68     public static void setEncoding(String encoding) {
 69         JDBCUtil.encoding = encoding;
 70     }
 71 
 72     public static String getPort() {
 73         return port;
 74     }
 75 
 76     public static void setPort(String port) {
 77         JDBCUtil.port = port;
 78     }
 79 
 80     public static String getHost() {
 81         return host;
 82     }
 83 
 84     public static void setHost(String host) {
 85         JDBCUtil.host = host;
 86     }
 87 
 88     public static String getPasswrod() {
 89         return passwrod;
 90     }
 91 
 92     public static void setPasswrod(String passwrod) {
 93         JDBCUtil.passwrod = passwrod;
 94     }
 95 
 96     public static String getUserName() {
 97         return userName;
 98     }
 99 
100     public static void setUserName(String userName) {
101         JDBCUtil.userName = userName;
102     }
103 
104     public static String getUrl() {
105         return url;
106     }
107 
108     public static void setUrl(String url) {
109         JDBCUtil.url = url;
110     }
111     
112     
113 }

 1 /**
 2  * 
 3  */
 4 package com.b510.hongten.jdbc;
 5 
 6 import java.sql.Connection;
 7 import java.sql.DriverManager;
 8 import java.sql.PreparedStatement;
 9 import java.sql.ResultSet;
10 import java.sql.SQLException;
11 
12 /**
13  * 
14  * @author Hongten</br>
15  * @date 2012-7-16
16  * 
17  */
18 public class JDBCTest {
19     @SuppressWarnings("static-access")
20     public static void main(String[] args) {
21         JDBCUtil jdbcUtil = new JDBCUtil();
22         String sql = "select * from mymails";
23         try {
24             Class.forName(jdbcUtil.getDriver());
25             Connection conn = DriverManager.getConnection(jdbcUtil.getUrl(), jdbcUtil.getUserName(), jdbcUtil.getPasswrod());
26             PreparedStatement ps = conn.prepareStatement(sql);
27             ResultSet rs = ps.executeQuery();
28             while (rs.next()) {
29                 System.out.println("id : " + rs.getInt(1) + " name : " + rs.getString(2) + " mail : " + rs.getString(3));
30             }
31             // 关闭记录集
32             if (rs != null) {
33                 try {
34                     rs.close();
35                 } catch (SQLException e) {
36                     e.printStackTrace();
37                 }
38             }
39 
40             // 关闭声明
41             if (ps != null) {
42                 try {
43                     ps.close();
44                 } catch (SQLException e) {
45                     e.printStackTrace();
46                 }
47             }
48 
49             // 关闭链接对象
50             if (conn != null) {
51                 try {
52                     conn.close();
53                 } catch (SQLException e) {
54                     e.printStackTrace();
55                 }
56             }
57         } catch (Exception e) {
58             e.printStackTrace();
59         }
60     }
61 
62 }