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@WebServlet("/HelloServlet")
public class HelloServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//request.getSession().setAttribute("hello","Hello Servlet!");
//response.sendRedirect(request.getContextPath()+"/01/02jstl.jsp");
/*客户端跳转需要在服务端Seesion存值,不建议*/
request.setAttribute("hello","Hello Servlet!");
//web中WEB-INF下的路径在客户端无法访问,在服务端可以访问,安全性!
RequestDispatcher rd=request.getRequestDispatcher("/WEB-INF/01/02jstl.jsp");
rd.forward(request,response);
/*服务端跳转,Dispatcher可以自动添加上下文路径,forward*/
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}
/////////////////////////多业务支持
@WebServlet("/user02.do")
public class UserServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public UserServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/*
* 动态获取访问的是哪一个操作
* 1.if else会随着方法的增多而增多,不易管理（反射）
* */
request.setCharacterEncoding("UTF-8");//post传送需在服务端设置编码格式
String method=request.getParameter("method");
if("list".equals(method)){
list(request,response);
}else if("register".equals(method)){
register(request,response);
}else if("add".equals(method)){
add(request,response);
}
}
protected void list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<User> users=(List<User>) request.getSession()
.getServletContext().getAttribute("storeUsers");
request.setAttribute("users", users);
request.getRequestDispatcher("/WEB-INF/user02/list.jsp").forward(request, response);
}
protected void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/WEB-INF/user02/register.jsp").forward(request, response);
}
protected void add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username=request.getParameter("username");
String nickname=request.getParameter("nickname");
int age=Integer.parseInt(request.getParameter("age"));
/*
* 此处将用户存储到application中
* */
List<User> users=(List<User>) request.getSession()
.getServletContext().getAttribute("storeUsers");
if(users==null){
users=new ArrayList<User>();
}
User u=new User(username,nickname,age);
System.out.println(u);
users.add(u);
request.getSession()
.getServletContext().setAttribute("storeUsers",users);
response.sendRedirect("user02.do?method=list");
}
}
//////////////////////////////////////////////////MVC 初步
public class BaseServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
try {
String method=request.getParameter("method");
Method m=this.getClass().getMethod(method,HttpServletRequest.class,HttpServletResponse.class);
String rel=(String) m.invoke(this,request,response);
String redirStr="redirect:";
if(rel.startsWith(redirStr)){//判断是服务端跳转还是客户端跳转
response.sendRedirect(rel.substring(redirStr.length()));
}else{
request.getRequestDispatcher("/WEB-INF/"+rel).forward(request, response);
}
} catch (SecurityException e) {
e.printStackTrace();
}catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
}
@WebServlet("/user03.do")
public class UserServlet extends BaseServlet {
private static final long serialVersionUID = 1L;
public UserServlet() {
super();
}
/*这是第3版,基于反射,父类BaseServlet继承HttpServlet实现service方法进行方法调用
* 所有本类作为子类不需要实现doPost()和doGet(),只需要自己的逻辑方法
* 不足之处:每个执行方法最后跳转代码都相同,应该想办法解决:参考list()和BaseServlet.class
* */
@SuppressWarnings("unchecked")
public String list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<User> users=(List<User>) request.getSession()
.getServletContext().getAttribute("storeUsers");
request.setAttribute("users", users);
//request.getRequestDispatcher("/WEB-INF/user03/list.jsp").forward(request, response);
return "user03/list.jsp";
}
public String register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//request.getRequestDispatcher("/WEB-INF/user03/register.jsp").forward(request, response);
return "user03/register.jsp";
}
public String delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("子类增加方法测试:delete");
return "user03/register.jsp";
}
public String update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("子类增加方法测试:update");
return "user03/update.jsp";
}
@SuppressWarnings("unchecked")
public String add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username=request.getParameter("username");
String nickname=request.getParameter("nickname");
int age=Integer.parseInt(request.getParameter("age"));
/*
* 此处将用户存储到application中
* */
List<User> users=(List<User>) request.getSession()
.getServletContext().getAttribute("storeUsers");
if(users==null){
users=new ArrayList<User>();
}
User u=new User(username,nickname,age);
System.out.println(u);
users.add(u);
request.getSession()
.getServletContext().setAttribute("storeUsers",users);
//response.sendRedirect("user03.do?method=list");
return "redirect:user03.do?method=list";
}
}
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原文地址：http://my.oschina.net/686991/blog/504615
