Question

PrintNamesServlet.java

此servlet打印输入的用户名

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name = "PrintNamesServlet")
public class PrintNamesServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("Ram Dhakal");
    }
}

CounterServlet.java

计算页面中的点击次数或访问次数

import javax.servlet.ServletException; import
> javax.servlet.annotation.WebServlet; import
> javax.servlet.http.HttpServlet; import
> javax.servlet.http.HttpServletRequest; import
> javax.servlet.http.HttpServletResponse; import java.io.IOException;
> import java.io.PrintWriter;
> 
> @WebServlet(name = "CounterServlet") public class CounterServlet
> extends HttpServlet {
>     int totalHits;
>     public void init() throws ServletException{
>         totalHits = 0;
>          }
>          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             PrintWriter out = response.getWriter();
>         out.print("Total visit count: " + totalHits++);
>     }  public void destroy(){
>            }
>            }

的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <servlet>
        <servlet-name>PrintNamesServlet</servlet-name>
        <servlet-class>PrintNamesServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>PrintNamesServlet</servlet-name>
        <url-pattern>/PrintNamesServlet</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>CounterServlet</servlet-name>
        <servlet-class>CounterServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>CounterServlet</servlet-name>
        <url-pattern>/CounterServlet</url-pattern>
    </servlet-mapping>
</web-app>

我收到错误：找不到网址的网页：http://localhost:8080/ 因为，我试图第一次运行servlet，我没有得到我的代码有什么问题。我在网址中输入了http://localhost:8080/PrintNamesServlet。

Answer 1

使用注释@WebServlet(name = "PrintNamesServlet") the时，不使用web.xml`映射。

您必须删除这些注释或向其添加urlMapping属性。

Answer 2

您使用过Servlet 3.0规范让我们来看看它

在Servlet 3.0中，可以使用@WebServlet

指定servlet元数据

@WebServlet(name="mytest", 
 urlPatterns={"/myurl"}) 
public class TestServlet extends javax.servlet.http.HttpServlet { 
 .... 
}

通过这种方式，可以使用注释中指定的url模式访问servlet。

   @@WebServlet(name="mytest",urlPatterns={"/myurl"})

根据该servlet使用

加入

  http://localhost:8080/myurl

在您的情况下，您只需要指定名称，您也必须指定urlPatterns，这样您就可以正确地调用servlet。

  @WebServlet(name = "CounterServlet",urlPatterns={"/CounterServlet"}) public class CounterServlet extends HttpServlet {}

您不需要使用web.xml文件。

servlet中的Http错误404

2 个答案: