数据库链接JDBC

 1 //代码演示：
 2 //我们封装一个工具类来提高代码的扩展性
 3 public class JDBCUtils {
 4           private static final String url="jdbc:mysql://localhost:3306/test";
 5           private static final String username="root";
 6           private static final String password = "root";
 7           /**
 8            * 注册驱动
 9            */
10           static {
11               try {
12                    Class.forName("com.mysql.jdbc.Driver");
13               } catch (ClassNotFoundException e) {
14                    // TODO Auto-generated catch block
15                    e.printStackTrace();
16               }
17           }
18           /**
19            * 获取链接
20            * @return
21            */
22           public static Connection getConnention() {
23               Connection connection=null;
24               try {
25                    connection = DriverManager.getConnection(url,username,password);
26               } catch (SQLException e) {
27                    // TODO Auto-generated catch block
28                    e.printStackTrace();
29               }
30               return connection;
31           }
32           /**
33            * 通过可变参关闭连接
34            * @param objects
35            */
36           public static void colse(Object ...objects) {
37               try {
38                    if (objects!=null && objects.length>0) {
39                         for(int i = 0;i<objects.length;i++) {
40                              if(objects[i] instanceof Statement) {
41                                   ((Statement)objects[i]).close();
42                              }else if(objects[i] instanceof Connection) {
43                                   ((Connection)objects[i]).close();
44                              }
45                         }
46                    }
47               } catch (Exception e) {
48                    e.printStackTrace();
49               }
50           }
51 }

 1 // 对工具类的使用
 2 public class JDBCDemo {
 3      public static void main(String[] args) {
 4           //获取链接
 5           Connection connection = JDBCUtils.getConnention();
 6           //获取执行者
 7           ResultSet resultSet=null;
 8           PreparedStatement pStatement=null;
 9  
10           //定义将要执行的sql语句
11           String sql = "select * from products where cno=?";
12           //存放结果集对象
13           List<Product> list = new ArrayList<Product>();
14           try {
15               //获取语句执行者对象
16               pStatement = connection.prepareStatement(sql);
17               //设置参数
18               pStatement.setInt(1, 1);
19               //执行查询操作
20               resultSet = pStatement.executeQuery();
21               //遍历结果集
22               while (resultSet.next()) {
23                    Product product = new Product();
24                    product.setId(resultSet.getInt("pid"));
25                    product.setName(resultSet.getString("pname"));
26                    product.setPrice(resultSet.getInt("price"));
27                    product.setNum(resultSet.getInt("pnum"));
28                    product.setCno(resultSet.getInt("cno"));
29                    product.setTimestamp(resultSet.getTimestamp("pdate"));
30                    list.add(product);
31               }
32           } catch (SQLException e) {
33               // TODO Auto-generated catch block
34               e.printStackTrace();
35           }finally {
36               //关闭连接
37               JDBCUtils.colse(pStatement,connection);
38           }
39           for (Product product : list) {
40               System.out.println(product);
41           }
42      }
43 }