MVC

Jdbcutil类中代码：
public class JdbcUtils extends HttpServlet {
private static final long serialVersionUID = 1L;
private static String url;
private static String username;
private static String password;
//让驱动只加载一次
static{
try {
Class.forName(“com.mysql.jdbc.Driver”);
System.out.println(“驱动加载成功”);
} catch (ClassNotFoundException e) {
System.out.println(“驱动加载失败”);
e.printStackTrace();
}
}
public JdbcUtils() {
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}

//init方法中的内容会在启动这个servlet时就执行，因为在配置文件中添加了1
@Override
public void init(ServletConfig config) throws ServletException {
//从配置文件中取得传给getConnection()的三个参数，
url=config.getInitParameter(“url”);
username=config.getInitParameter(“username”);
password=config.getInitParameter(“password”);
//System.out.println(getConn());
System.out.println(“我诞生了，哈哈哈哈哈”);
}

public static Connection getConn(){    Connection conn=null;    try {        conn=DriverManager.getConnection(url, username, password);    } catch (SQLException e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    return conn;}public static void close(Connection conn,Statement stmt,ResultSet set){    if(set!=null){        try {            set.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    if(stmt!=null){        try {            stmt.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    if(conn!=null){        try {            conn.close();        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}

}
配置文件web.xml部分代码：

JdbcUtil
/jdbc


JdbcUtil
com.xmt.utils.JdbcUtils

url
jdbc:mysql://localhost:3306/mytest


username
root


password
ROOT

1

StudentServlet
/stuServlet

StudentServlet
com.xmt.contral.StudentServlet

studentDao类中代码：
public class StudentDao {

public List<Student> getStudentList(String sql){    Connection conn=JdbcUtils.getConn();    List<Student> list=new ArrayList<Student>();    Statement stmt=null;    ResultSet set=null;    try {        //得到操作数据库的对象stmt        stmt=conn.createStatement();        set=stmt.executeQuery(sql);        while(set.next()){            Student student=new Student();            student.setSname(set.getString("Sname"));            student.setSage(set.getInt("Sage"));            student.setSsex(set.getString("Ssex"));            student.setSphone(set.getString("Sphone"));            list.add(student);        }    } catch (SQLException e) {        e.printStackTrace();    }finally{        JdbcUtils.close(conn, stmt, set);    }    return list;}

}
StudentService 中代码：
public class StudentService {
public List StudentList(){
String sql=”select * from student”;
StudentDao sd=new StudentDao();
List list=sd.getStudentList(sql);
return list;

}

}
StudentServlet中代码：
public class StudentServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public StudentServlet() {    super();    // TODO Auto-generated constructor stub}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    StudentService stuService=new StudentService();    List<Student> list=stuService.StudentList();    //将集合存进request中    request.setAttribute("StuList", list);    //实现跳转，并且可以携带数据    request.getRequestDispatcher("index.jsp").forward(request, response);}

}
以上代码基本可以实现从数据库中读取所有数据了，它完成了servlet与数据库间的交互，接下来只要把获取到的数据设置到页面上对应的位置即可。
在index.jsp文件中写Java代码要讲Java代码放在<% java%>中间。
如：<%
for(int i=0;i