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 getStudentList(String sql){ Connection conn=JdbcUtils.getConn(); List list=new ArrayList(); 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 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