I made a bulletin board using Docker 1
What is this
A memo when implementing Chapter 3 of this book on a Docker container for studying Docker and Web application creation.
file organization
$ tree .
.
├── Dockerfile
└── testbbs
└── WEB-INF
├── classes
├── src
│ ├── Message.java
│ ├── PostBBS.java
│ └── ShowBBS.java
└── web.xml
4 directories, 5 files
Dockerfile
Dockerfile
FROM tomcat:8.5.54-jdk11-adoptopenjdk-hotspot
WORKDIR /usr/local/tomcat/webapps/
RUN mkdir -p ./testbbs
COPY ./testbbs ./testbbs/
RUN javac -classpath $CATALINA_HOME/lib/servlet-api.jar -d ./testbbs/WEB-INF/classes ./testbbs/WEB-INF/src/*.java
Java file
Same as the reference book.
Message.java
import java.util.*;
public class Message {
public static ArrayList<Message> messageList = new ArrayList<Message>();
String title;
String handle;
String message;
Date date;
Message (String title, String handle, String message) {
this.title = title;
this.handle = handle;
this.message = message;
this.date = new Date();
}
}
PostBBS.java
import java.io.*;
import javax.servlet.http.*;
public class PostBBS extends HttpServlet {
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws UnsupportedEncodingException, IOException {
request.setCharacterEncoding("UTF-8");
Message newMessage = new Message(request.getParameter("title"),
request.getParameter("handle"),
request.getParameter("message"));
Message.messageList.add(0, newMessage);
response.sendRedirect("/testbbs/ShowBBS");
}
}
ShowBBS.java
import java.io.*;
import javax.servlet.http.*;
public class ShowBBS extends HttpServlet {
private String espaceHTML (String src) {
return src.replace ("&", "&").replace("<", "<")
.replace (">", ">").replace ("\"", """)
.replace ("'", "'");
}
@Override
public void doGet (HttpServletRequest request, HttpServletResponse response)
throws IOException {
response.setContentType("text/html; charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Test bulletin board</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Test bulletin board</h1>");
out.println("<form action='/testbbs/PostBBS' method='post'>");
out.println("title:<input type='text' name='title' size='60'>");
out.println("<br />");
out.println("Handle name:<input type='text' name='handle'>");
out.println("<br />");
out.println("<textarea name='message' rows='4' cols='60'></textarea>");
out.println("<br />");
out.println("<input type='submit' />");
out.println("</form>");
out.println("<hr />");
for (Message message: Message.messageList) {
out.println("<p> 『" + espaceHTML(message.title) + "』 ");
out.println(espaceHTML(message.handle) + "Mr. ");
out.println(espaceHTML(message.date.toString()) + "</p>");
out.println("<p>");
out.println(espaceHTML(message.message).replace("\r\n", "<br />"));
out.println("</p><hr />");
}
out.println("</body>");
out.println("</html>");
}
}
web.xml file
This is the same as a book.
web.xml
<web-app xmlns="http://xmlns.jcp.org/xml/nx/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"
metadata-complete="true">
<servlet>
<servlet-name>ShowBBS</servlet-name>
<servlet-class>ShowBBS</servlet-class>
</servlet>
<servlet>
<servlet-name>PostBBS</servlet-name>
<servlet-class>PostBBS</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ShowBBS</servlet-name>
<url-pattern>/ShowBBS</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>PostBBS</servlet-name>
<url-pattern>/PostBBS</url-pattern>
</servlet-mapping>
</web-app>
Build and run
$ docker build -t henacat .
Sending build context to Docker daemon 11.78kB
Step 1/6 : FROM tomcat:8.5.54-jdk11-adoptopenjdk-hotspot
---> 66317f378ae0
Step 2/6 : RUN apt-get update && apt-get install -y wget
---> Using cache
---> 871dd39a71cc
Step 3/6 : WORKDIR /usr/local/tomcat/webapps/
---> Using cache
---> 19d29e246ff6
Step 4/6 : RUN mkdir -p ./testbbs
---> Using cache
---> c2765cdc59e3
Step 5/6 : COPY ./testbbs ./testbbs/
---> Using cache
---> dbd09272e03b
Step 6/6 : RUN javac -classpath $CATALINA_HOME/lib/servlet-api.jar -d ./testbbs/WEB-INF/classes ./testbbs/WEB-INF/src/*.java
---> Using cache
---> 41e02fb5b101
Successfully built 41e02fb5b101
Successfully tagged henacat:latest
$ docker run -d -p 8080:8080 -it henacat
$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
249799090cb1 henacat "catalina.sh run" About a minute ago Up About a minute 0.0.0.0:8080->8080/tcp elegant_ishizaka
When you access http: // localhost: 8080/testbbs/ShowBBS, the bulletin board is displayed properly.
I was addicted to
The first Docker image I used was tomcat: 10.0.0-jdk11-adoptopenjdk-hotspot, but it didn't compile. Apparently I can't find the package for the Servlet. I wondered if I made a mistake in the classpath and tried various changes, but the compile error did not go away, and when I went to the document thinking that it was a problem with tomcat, it seems that the package name changed from tomcat-10. In tomcat-8, it was javax.servlet.http, but in tomcat-10, it is jakarta.servlet.http, so the package cannot be found and an error is thrown. When. That's why I solved it safely by using the same tomcat-8 Docker image as the book.
References
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