[Java Servlet] The road of Senri is also the third step from the first step

Current progress

• Transition source jsp (login.jsp)
• Transition destination jsp (mypage.jsp)
• Servlet class (Login)

It still doesn't work with this alone From now on, we will link the transition source jsp with the Jakarta Servlet to be started.

[When creating a project in the first step](https://qiita.com/hatopo/items/3cd12bda5d995703c293#%E3%83%97%E3%83%AD%E3%82%B8%E3%82%A7% E3% 82% AF% E3% 83% 88% E4% BD% 9C% E3% 82% 8A% E3% 81% BE% E3% 81% 97% E3% 82% 87% E3% 81% 86), By checking [Generate web.xml deployment descriptor], I think that the following files are created under WEB-INF.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>ServletApp</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

Probably the above code is also written automatically, but for the time being, explanation

• \ <display-name > ・ ・ ・ Project name This time ServletApp
• \ <welcome-file > ・ ・ ・ When ～ / project name / is specified instead of ～ / project name / jsp file name likehttp: // localhost: 8080 / ServletApp / Specify the file you want to transition to
  I haven't created default or index right now, so let's specify login.jsp for the time being.

Now, let's add various things under <welcome-file-list>

<servlet>
	<servlet-name>login</servlet-name>
	<servlet-class>login.LoginServlet</servlet-class>
</servlet>

In <servlet-class>, specify the relative path of the file you want to call starting from the project folder (ServletApp). You can call ～ /ServletApp/login/LoginServlet.java by writing as above. Give <servlet-name> a temporary name for this class (use it just below)

<servlet-mapping>
	<servlet-name>login</servlet-name>
	<url-pattern>/mypage</url-pattern>
</servlet-mapping>

In <url-pattern>, specify the action path of the form tag of the calling jsp. The jsp side is / ServletApp / mypage, but since this is the starting point of the project folder, it will be / mypage. For <servlet-name>, specify the name of the <servlet> you want to call.

This makes it possible to make screen transitions. The above is a series of flow

Let's run

Click the green icon on the server If the server does not appear, open the view with [Window]-[View View]-[Others] on the menu bar and select [Server] to open it. ↑ Like this Let's specify http: // localhost: 8080 / ServletApp / login.jsp to display the screen. (If you specified login.jsp in <welcome-file> earlier, you can also display it in http: // localhost: 8080 / ServletApp /, so please try it.

It's too simple, but I was able to see the screen Try typing hatopo and pressing the login button ... You have successfully passed the parameters!

Continue to [Java Servlet] Senri no Michi from one step to the fourth step