mvc: Example for SimpleController interface, SimpleHandlerAdapter.

mvc/src/main/java/com/dongho/config/mvc/adapter/SimpleHandlerAdapter.java

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+package com.dongho.config.mvc.adapter;
+
+import com.dongho.config.mvc.annotation.RequiredParams;
+import com.dongho.config.mvc.annotation.ViewName;
+import com.dongho.config.mvc.controller.SimpleController;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.stereotype.Component;
+import org.springframework.util.ReflectionUtils;
+import org.springframework.web.servlet.HandlerAdapter;
+import org.springframework.web.servlet.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+import java.util.Map;
+
+@Component
+public class SimpleHandlerAdapter implements HandlerAdapter {
+
+    @Override
+    public boolean supports(Object handler) {
+        return handler instanceof SimpleController;
+    }
+
+    @Override
+    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
+        Method m = ReflectionUtils.findMethod(handler.getClass(), "control", Map.class, Map.class);
+        ViewName viewName = AnnotationUtils.getAnnotation(m, ViewName.class);
+        RequiredParams requiredParams = AnnotationUtils.getAnnotation(m, RequiredParams.class);
+
+        Map<String, String> params = new HashMap<>();
+        for (String param : requiredParams.value()) {
+            String value = request.getParameter(param);
+
+            if (value == null) {
+                throw new IllegalStateException();
+            }
+
+            params.put(param, value);
+        }
+
+        Map<String, Object> model = new HashMap<>();
+        SimpleController.class.cast(handler).control(params, model);
+
+        return new ModelAndView(viewName.value(), model);
+    }
+
+    @Override
+    public long getLastModified(HttpServletRequest httpServletRequest, Object o) {
+        return -1;
+    }
+
+}

mvc/src/main/java/com/dongho/config/mvc/annotation/RequiredParams.java

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+package com.dongho.config.mvc.annotation;
+
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Inherited
+public @interface RequiredParams {
+
+    String[] value();
+
+}

mvc/src/main/java/com/dongho/config/mvc/annotation/ViewName.java

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+package com.dongho.config.mvc.annotation;
+
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Inherited
+public @interface ViewName {
+
+    String value();
+
+}

mvc/src/main/java/com/dongho/config/mvc/controller/SimpleController.java

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+package com.dongho.config.mvc.controller;
+
+import java.util.Map;
+
+public interface SimpleController {
+
+    void control(Map<String, String> params, Map<String, Object> model);
+
+}

mvc/src/main/java/com/dongho/web/HelloSimpleController.java

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+package com.dongho.web;
+
+import com.dongho.config.mvc.annotation.RequiredParams;
+import com.dongho.config.mvc.annotation.ViewName;
+import com.dongho.config.mvc.controller.SimpleController;
+import org.springframework.stereotype.Component;
+
+import java.util.Map;
+
+@Component("/simple-hello")
+public class HelloSimpleController implements SimpleController {
+
+    @ViewName("/simple-hello")
+    @RequiredParams({"name"})
+    @Override
+    public void control(Map<String, String> params, Map<String, Object> model) {
+        model.put("message", "Hello " + params.get("name"));
+    }
+
+}