feat: 강의 등록/조회/수정/삭제 기능 추가

.gitignore

@@ -42,3 +42,6 @@ bin/
 
 ### Mac OS ###
 .DS_Store\ntomcat.8080/
+
+## tomcat
+**/tomcat.8080

src/main/java/com/diy/app/LectureServlet.java

@@ -0,0 +1,125 @@
+package com.diy.app;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+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.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.IntStream;
+
+@WebServlet("/lectures")
+public class LectureServlet  extends HttpServlet {
+
+    private final ObjectMapper objectMapper = new ObjectMapper();
+    private final List<Lecture> lectures = new ArrayList<>();
+    private Long idx = 1L;
+
+    @Override
+    public void init() throws ServletException {
+        System.out.println("[INIT] servlet initialized");
+
+        IntStream.rangeClosed(1, 5)
+                .forEach(i -> lectures.add(new Lecture(idx++, "TEST"+i, BigDecimal.valueOf(i*10000))));
+
+        super.init();
+    }
+
+    /**
+     * 강의 목록 조회
+      */
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        System.out.println("[GET] lecture list");
+
+        req.setAttribute("lectures", lectures);
+
+        req.getRequestDispatcher("/lecture-list.jsp").forward(req, resp);
+    }
+
+    /**
+     * 강의 등록
+     */
+    @Override
+    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+        System.out.println("[POST] lecture register");
+
+        Map<String, Object> payload = objectMapper.readValue(req.getReader(), Map.class);
+        Lecture lecture = new Lecture(
+                idx++,
+                payload.get("name").toString(),
+                new BigDecimal(payload.get("price").toString())
+        );
+        lectures.add(lecture);
+
+        resp.sendRedirect("/lectures");
+    }
+
+    /**
+     * 강의 수정
+     */
+    @Override
+    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+        System.out.println("[PUT] lecture modify");
+
+        // req: id, name, price
+        Map<String, Object> payload = objectMapper.readValue(req.getReader(), Map.class);
+        Long id = Long.valueOf(payload.get("id").toString());
+
+        for (int i = 0; i < lectures.size(); i++) {
+            var orgLecture = lectures.get(i);
+            if (id.equals(orgLecture.getId())) {
+                lectures.set(i, new Lecture(
+                        orgLecture.getId(),
+                        payload.get("name").toString(),
+                        new BigDecimal(payload.get("price").toString())
+                ));
+                break;
+            }
+        }
+    }
+
+    /**
+     * 강의 삭제
+     */
+    @Override
+    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        System.out.println("[DELETE] lecture delete");
+
+        // req: id
+        Map<String, Object> payload = objectMapper.readValue(req.getReader(), Map.class);
+        Long id = Long.valueOf(payload.get("id").toString());
+
+        lectures.removeIf(lecture -> id.equals(lecture.getId()));
+    }
+
+    public static class Lecture {
+        private final Long id;
+        private final String name;
+        private final BigDecimal price;
+
+        private Lecture(Long id, String name, BigDecimal price) {
+            this.id = id;
+            this.name = name;
+            this.price = price;
+        }
+
+        public Long getId() {
+            return id;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public BigDecimal getPrice() {
+            return price;
+        }
+    }
+}

src/main/java/com/diy/app/Main.java

@@ -1,6 +1,78 @@
 package com.diy.app;
 
+import com.diy.framework.web.server.TomcatWebServer;
+
 public class Main {
     public static void main(String[] args) {
+
+        final TomcatWebServer tomcatWebServer = new TomcatWebServer();
+        tomcatWebServer.start();
+
+
+        // version 3
+        /*
+        final Tomcat tomcat = new Tomcat();
+        tomcat.setPort(8080);
+
+        try {
+            tomcat.start();
+            final Thread awaitThread = new Thread(() -> tomcat.getServer().await());
+            awaitThread.start();
+
+            System.out.println("서버 실행");
+        } catch (LifecycleException e) {
+            throw new RuntimeException(e);
+        }
+
+         */
+
+        // version 2
+        /*
+        final Tomcat tomcat = new Tomcat();
+        tomcat.setPort(8080);
+
+        new Thread(() -> {
+            try {
+                tomcat.start();
+                // while true 대신 await
+                //  thread 를 blocking-> 서버가 다른 스택에서 멈춰서 다른 로직 수행 불가
+                //  -> 별도 스레드 실행하면 해결되지만, 톰캣 실행 흐름이 다른 스레드로 넘어가 스레드 간 컨텍스트 공유가 어려움
+                //  => 톰캣 실행은 메인 스레드에서 하고, await 로 스레드가 종료되지 않게 하는 메서드를 다른 스레드로 넘겨주면 됨 (v3)
+                tomcat.getServer().await();
+            } catch (
+    LifecycleException e) {
+                throw new RuntimeException();
+            }
+        }).start();
+        System.out.println("Hello, World!");
+
+         */
+
+        // version 1
+        /*
+        // 웹 요청을 직접 받는 대신 => Spring Boot 의 Embedded Tomcat 사용 (v2)
+        try (final ServerSocket serverSocket = new ServerSocket(8080)) {
+            // 서버가 요청을 계속 받을 수 있도록 하기 위해 추가
+            while (true) {
+                try (final Socket clientSocket = serverSocket.accept()) {
+                    final BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
+                    final PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
+
+                    // HTTP 요청 읽기
+                    final String request = in.readLine();
+                    System.out.println("요청: " + request);
+
+                    // HTTP 응답 전송
+                    out.println("HTTP/1.1 200 OK");
+                    out.println("Content-Type: text/html; charset=UTF-8");
+                    out.println();
+                    out.println("<html><body><h1>Hello, World!</h1></body></html>");
+                }
+            }
+        } catch (final IOException e) {
+            System.err.println("error = " + e.getMessage());
+        }
+
+         */
     }
 }

src/main/java/com/diy/framework/web/server/TomcatWebServer.java

@@ -38,7 +38,7 @@ private void setServerContext() {
         final String resourcesPath = Paths.get("src", "main", "resources").toString();
         final String absoluteResourcesPath = new File(resourcesPath).getAbsolutePath();
 
-        final Context context = this.tomcat.addWebapp("/", absoluteResourcesPath);
+        final Context context = this.tomcat.addWebapp("", absoluteResourcesPath);
 
         context.setRequestCharacterEncoding("UTF-8");
         context.setResponseCharacterEncoding("UTF-8");

src/main/resources/lecture-list.jsp

@@ -11,8 +11,8 @@
 <a href="/lecture-registration.jsp">등록</a>
 <c:forEach var="lecture" items="${lectures}">
     <li>id: ${lecture.id}</li>
-    <li>pw: ${lecture.name}</li>
-    <li>pw: ${lecture.price}</li>
+    <li>name: ${lecture.name}</li>
+    <li>price: ${lecture.price}</li>
     <br>
 </c:forEach>
 </body>

src/main/resources/lecture-registration.jsp

@@ -8,7 +8,7 @@
     <title>강의 등록</title>
 </head>
 <body>
-<form id="registrationForm">
+<form id="registrationForm" action="/lectures" method="post">
     <label for="name">이름:</label>
     <input type="text" id="name" name="name" required>
     <label for="price">가격:</label>