[JAVA] Create a tomcat project using Eclipse

	static String result = "";

// ↑ Add up to here ~~~

7. Change doGet () in SampleServlet.java to the following implementation. When the WEB server is accessed from the WEB browser, the HTML file of the WEB page is read and this is set in the response body so that it responds.

   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   	// TODO Auto-generated method stub
   

//super.doGet (req, resp); // Comment out

// ↓ Add from here // Perform character encoding to prevent garbled Japanese characters resp.setContentType("text/html; charset=UTF-8");

// Create a web screen to be displayed on the client's web browser PrintWriter out = resp.getWriter(); out.println(""); out.println(head); out.println(""); out.println(msg); out.println(form); out.println(""); out.println(""); out.close(); // ↑ Add up to here } ~~~

8. Change doPost () in SampleServlet.java to the following implementation. When data is sent from the form of the web browser to the web server, the request parameter (data sent from the client) is acquired and set in the response body to respond.

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
   	// TODO Auto-generated method stub
   

//super.doPost (req, resp); // Comment out

// ↓ Add from here req.setCharacterEncoding ("UTF-8"); // Character encoding (Japanese character garbled measures) resp.setContentType ("text / html; charset = UTF-8"); // Character encoding (measures against garbled Japanese characters)

	try{

// Get the written text if the "write" button is pressed if(req.getParameter("send").equalsIgnoreCase("write")){ result += "

// Create a web screen to be displayed on the client's web browser PrintWriter out = resp.getWriter(); out.println(""); out.println(head); out.println(""); out.println(msg); out.println(form); out.println(result); out.println(""); out.println(""); out.close(); // ↑ Add up to here } ~~~

web.xml creation

Create web.xml. web.xml is a file that configures the Servlet container.

1. Select the tree node "WEB-INF" on "Package Explorer", right-click and click the pop-up menu "New"> "Other" to launch the "New" dialog.

2. Click XML> XML file to launch the New XML file dialog.

3. Enter "web.xml" in the "File name" field and press the "Finish" button to add the tree node "web.xml" on the "Package Explorer".

4. Select the tree node "web.xml" on the "Package Explorer", right-click and click the pop-up menu "Open With"> "Generic Text Editor".

   <?xml version="1.0" encoding="UTF-8"?>
   

5. Add the following code to web.xml.

   <?xml version="1.0" encoding="UTF-8"?>
   
   

<!-↓ Add from here-> sample sample.SampleServlet

	<servlet-mapping>
		<servlet-name>sample</servlet-name>					<!-- Servlet name -->
		<url-pattern>/servlet</url-pattern>					<!-- URL pattern -->
	</servlet-mapping>
</web-app>

<!-↑ Add up to here-> ~~~

Build

For builds, enable automatic builds so that they build automatically.

1. Select the top node of the tree on "Package Explorer", right-click and click the pop-up menu "Reflesh" to automatically update the file structure of the tree on "Package Explorer" to the current state. ..

2. Check "Project"> "Build Automatically" in the main menu to enable automatic build. (If the build is not executed, click "Project"> "Clean" in the main menu.)

Run

Run it when you have a build. First, use Eclipse to start a web server on Windows and access it from a web browser.

1. Click the icon "Restart Tomcat" on the main menu.

2. When you start a web browser and access the following URL, the GET method is sent from the client to the server, and the following web page is displayed. http://localhost:8080/sample/servlet

3. Enter the text and press the "write" button, the client will send the POST method to the server and the following web page will be displayed.

Export project

Make a backup of your project before deleting it.

1. Stop Tomcat.

2. Select the top node of the tree on "Package Explorer", right-click and click the pop-up menu "Export" to launch the "Export" dialog.

3. Select General> File System and press the Next button.

4. Check the check box of the project.

5. Enter the export destination path in the "To directory" field and press the "Finish" button.

Project import

If you want to restart the project, import the backed up project.

1. Create a project according to the "Create project" item.

2. Select the top node of the tree on "Package Explorer", right-click and click the pop-up menu "Import" to launch the "Import" dialog.

3. Select General> File System and press the Next button.

4. Check the check box of the project.

5. Enter the import destination path in the "Into folder" field and press the "Finish" button.

6. When asked "Overwrite'.classpath' in folder {project name}?", Select "Not to all".

WAR file creation

Create a WAR file (a collection of files necessary for the operation of the WEB application) to deploy (make it available).

1. Click Project> Properties on the main menu to launch the Properties dialog.

2. Select the tree node "Tomcat", open the "WAR Export Settings" tab and press the "Browse" button to launch the "Open" dialog.

3. Enter the WAR file name to be saved in the "File name" field and click the "Open" button.

4. When the path of the WAR file to be saved is reflected in the "WAR file to export" field, click the "Apply and close" button.

5. Select the top node of the tree on "Package Explorer", right-click and execute "Tomcat project"> "Create WAR file according to project settings".

6. A WAR file will be generated in the path set in the "WAR file to export" field.

Deployment environment

From here, prepare for deployment. Here, we will deploy to Ubuntu.

• Ubuntu 20.04 LTS
• OpenJDK 11
• Tomcat 9

Deployment environment construction ①: OpenJDK 11 installation

First, install Java.

1. Install OpenJDK 11.

   $ sudo apt-get install openjdk-11-jdk
   

2. Check the Java version you have installed.

$ java --version openjdk 11.0.8 2020-07-14 OpenJDK Runtime Environment (build 11.0.8+10-post-Ubuntu-0ubuntu120.04) OpenJDK 64-Bit Server VM (build 11.0.8+10-post-Ubuntu-0ubuntu120.04, mixed mode, sharing) ~~~

Deployment environment construction ②: TOMCAT installation

Then install TOMCAT.

1. Access the following site and click "Tomcat 9" in the "Download" item on the left. http://tomcat.apache.org/download-80.cgi

2. Click "tar.gz" under "Core" in "Binary Distributions". ⇒ "apache-tomcat-9.0.37.zip" will be downloaded. https://tomcat.apache.org/download-90.cgi

3. When the download is complete, unzip it to any directory. Here, unzip to / opt.

   $ sudo tar zxvf apache-tomcat-9.0.37.tar.gz -C /opt
   

4. Make sure it is unzipped to / opt.

   $ ls /opt/apache-tomcat-9.0.37/
   BUILDING.txt  CONTRIBUTING.md  LICENSE  NOTICE  README.md  RELEASE-NOTES  RUNNING.txt  bin  conf  lib  logs  temp  webapps  work
   

Deploy

When the deployment environment is ready, deploy it.

1. The default setting of tomcat is root user because no user other than root user has execute permission.

   $ sudo su
   

2. Copy the created WAR file to the folder under webapps of TOMCAT.

   # mv sample.war /opt/apache-tomcat-9.0.37/webapps
   

3. Start TOMCAT.

   # cd /opt/apache-tomcat-9.0.37/bin
   # sh startup.sh
   

4. When you start a web browser and access the following URL, the client sends a GET method to the server and the following web page is displayed. http: // {IP address of the deployed PC}: 8080 / sample / servlet

5. Enter the text and press the "write" button, the client will send the POST method to the server and a web page like the one below will be displayed.

6. Exit TOMCAT.

   # sh shutdown.sh