初学servlet 看了韩顺平的视频， 写了简单用户登录的代码，继承了Httpservlet ，发现不能进行页面跳转，各位大神看看，小弟没分，真心求助
Login.java
public class Login extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
try{
res.setContentType("text/html;charset=gbk");
PrintWriter pw=res.getWriter();
pw.println("<html>");
pw.println("<body>");
pw.println("<h1>登陆界面</h1>");
pw.println("<form action=lo method=post>");
pw.println("用户名:<input type=text name=username</br>");
pw.println("密码:<input type=password name=passwd></br>");
pw.println("<input type=submit value=login>");
pw.println("</form>");
pw.println("</body>");
pw.println("</html>");
}
catch(Exception e){
e.getStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}
LoginCl.java
public class LoginCl extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
try{
String w=req.getParameter("username");
String s=req.getParameter("passwd");
if(w.equals("sp")&&s.equals("123")){
res.sendRedirect("wel");
}
else
{
res.sendRedirect("login");
}
}
catch(Exception e){
e.getStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doPost(req,res);
}
}
Wel.java
public class Wel extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
try{
PrintWriter pw=res.getWriter();
pw.println("hello,welcom");
}
catch(Exception e){
e.getStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doGet(req,res);
}
}
Web.xml
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>com.hehang.Login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>logincl</servlet-name>
<servlet-class>com.hehang.LoginCl</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>logincl</servlet-name>
<url-pattern>/lo</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>wel</servlet-name>
<servlet-class>com.hehang.Wel</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>wel</servlet-name>
<url-pattern>/wel</url-pattern>
</servlet-mapping>
[解决办法]
pw.println("<form action=lo method=post>");
你这个请求的方法是post
public void doPost(HttpServletRequest req,HttpServletResponse res){
this.doPost(req,res);
}
但是你处理的时候是在doGet里面做的，而doPost()方法里面又没调用doGet，所以进去就一片空白了
把 this.doPost(req,res)改为this.doGet(req,res);
[解决办法]
正解
[解决办法]
你要保证doGet中写的逻辑不会导致页面空白，redirect到哪个servlet了，在那个servlet里同样调试下