#35 springboot: servlet container initializer

springboot/server/src/main/java/hello/container/AppInit.java

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+package hello.container;
+
+import jakarta.servlet.ServletContext;
+
+public interface AppInit {
+    void onStartup(ServletContext servletContext);
+}

springboot/server/src/main/java/hello/container/AppInitV1Servlet.java

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+package hello.container;
+
+import hello.servlet.HelloServlet;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletRegistration;
+
+public class AppInitV1Servlet implements AppInit {
+    @Override
+    public void onStartup(ServletContext servletContext) {
+        System.out.println("AppInitV1Servlet.onStartup");
+
+        // 서블릿 코드 등록
+        ServletRegistration.Dynamic helloServlet =
+                servletContext.addServlet("helloServlet", new HelloServlet());
+
+        helloServlet.addMapping("/hello-servlet");
+    }
+}

springboot/server/src/main/java/hello/container/MyContainerInitV1.java

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+package hello.container;
+
+import jakarta.servlet.ServletContainerInitializer;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletException;
+
+import java.util.Set;
+
+public class MyContainerInitV1 implements ServletContainerInitializer {
+    @Override
+    public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException {
+        System.out.println("MyContainer.onStartup");
+        System.out.println("c = " + c);
+        System.out.println("ctx = " + ctx);
+    }
+}

springboot/server/src/main/java/hello/container/MyContainerInitV2.java

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+package hello.container;
+
+import jakarta.servlet.ServletContainerInitializer;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.annotation.HandlesTypes;
+
+import java.util.Set;
+
+@HandlesTypes(AppInit.class)
+public class MyContainerInitV2 implements ServletContainerInitializer {
+    @Override
+    public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException {
+        System.out.println("MyContainerInitV2.onStartup");
+        System.out.println("c = " + c);
+
+
+        for (Class<?> appInitClass : c) {
+            try {
+                AppInit appInit = (AppInit) appInitClass.getDeclaredConstructor().newInstance();
+                appInit.onStartup(ctx);
+            } catch (Exception e) {
+                throw new RuntimeException();
+            }
+        }
+    }
+}

springboot/server/src/main/java/hello/servlet/HelloServlet.java

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+package hello.servlet;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+import java.io.IOException;
+
+public class HelloServlet extends HttpServlet {
+    @Override
+    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        System.out.println("HelloServlet.service");
+        resp.getWriter().println("hello servlet!");
+    }
+}

springboot/server/src/main/resources/META-INF/services/jakarta.servlet.ServletContainerInitializer

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+hello.container.MyContainerInitV1
+hello.container.MyContainerInitV2