jdbc数据库链接之抽取工具类

来源：互联网发布：金融大数据对股市预测编辑：程序博客网时间：2024/05/26 07:30

jdbc工具类抽取分为两部分

1.创建连接

2.关闭所有链接。

案例如下：

public class DBUtils {
    private static String driverClass;
    private static String url;
    private static String username;
    private static String password;
    static{
       ResourceBundle rb=ResourceBundle.getBundle("dbinfo");
       driverClass=rb.getString("driverClass");
       url=rb.getString("url");
       username=rb.getString("username");
       password=rb.getString("password");
       System.out.println(driverClass+"======="+url+"=============="+username+"-------------"+password);
       try {
           Class.forName(driverClass);
       } catch (ClassNotFoundException e) {
           e.printStackTrace();
       }
    }
    //创建连接
    public static Connection getConnection() throws SQLException{
       return DriverManager.getConnection(url,username,password);
    }
    //关闭资源
    public static void closeAll(ResultSet rs,Statement stmt,Connection conn){
       if(rs!=null){
           try {
               rs.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
           rs=null;
       }
       if(stmt!=null){
           try {
               stmt.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
           stmt=null;
       }
       if(conn!=null){
           try {
               conn.close();
           } catch (SQLException e) {
               e.printStackTrace();
           }
           conn=null;
       }
    }
}

3.dbinfo.properties文件（注意文件中不包含分号）

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/shop
username=root
password=123

4.junit测试：

public class TestCurd {
   @Test
    public void testSelect(){
           Connection conn=null;
           Statement stmt=null;
           ResultSet rs=null;
           try {
           conn=DBUtils.getConnection();
           stmt=conn.createStatement();
           rs=stmt.executeQuery("select * from users");
           List<User> list=new ArrayList<User>();
           while(rs.next()){
               User u=new User();
               u.setId(rs.getInt(1));
               u.setName(rs.getString(2));
               u.setPassword(rs.getString(3));
               u.setBirthday(rs.getString(5));
               u.setEmail(rs.getString(4));
               list.add(u);
           }
           for(User user:list){
               System.out.println(user);
           }
           } catch (SQLException e) {
           e.printStackTrace();
       }finally{
           DBUtils.closeAll(rs, stmt, conn);
       }
    }
}

4.1 插入操作：

案例代码如下：

public void testInsert() {
       Connection conn = null;
       PreparedStatement stmt = null;
       try {
           conn = DBUtils.getConnection();
           stmt=conn.prepareStatement("insert into users(id,username,password,email,birthday)values(?,?,?,?,?)");
            stmt.setInt(1, 20);
            stmt.setString(2, "zxg");
            stmt.setString(3, "123");
            stmt.setString(4, "1009@qq.com");
            stmt.setString(5, "1993-05-25");
            int i=stmt.executeUpdate();
            if(i>0){
               System.out.println("success");
            }
       } catch (SQLException e) {
           e.printStackTrace();
       }finally{
           DBUtils.closeAll(null, stmt, conn);
       }
   }

简单的CRUD操作，可以只替换或修改测试部分的代码和sql语句即可；

阅读全文

1 0