annotation dispatch

Author: vison.cao

pom.xml

@@ -50,6 +50,11 @@
             <artifactId>tomcat-websocket</artifactId>
             <version>${tomcat.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.reflections</groupId>
+            <artifactId>reflections</artifactId>
+            <version>0.9.12</version>
+        </dependency>
     </dependencies>
 
     <build>

readme.md

@@ -0,0 +1 @@
+

src/main/java/com/vison/webmvc/Test.java

@@ -0,0 +1,36 @@
+package com.vison.webmvc;
+
+import java.lang.reflect.Method;
+
+/**
+ *
+ * @author vison.cao <visonforcoding@gmail.com>
+ */
+public class Test {
+    
+    public static void main(String[] args) throws Exception {
+        Class stdClass = Student.class;
+        Method method = stdClass.getMethod("getScore", String.class);
+        Object obj = stdClass.getDeclaredConstructor().newInstance();
+        System.out.print(method.invoke(obj, "888"));
+    }
+    
+}
+
+class Student extends Person {
+    
+    public int getScore(String type) {
+        return 99;
+    }
+    
+    private int getGrade(int year) {
+        return 1;
+    }
+}
+
+class Person {
+    
+    public String getName() {
+        return "Person";
+    }
+}

src/main/java/com/vison/webmvc/controller/UserController.java

@@ -0,0 +1,21 @@
+package com.vison.webmvc.controller;
+
+import com.vison.webmvc.framework.GetMapping;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ *
+ * @author vison.cao <visonforcoding@gmail.com>
+ */
+public class UserController {
+
+    public UserController() {
+    }
+
+    @GetMapping(path = "/user/profile")
+    public String profile(HttpServletRequest request, HttpServletResponse response) {
+        return "i am user profile";
+    }
+
+}

src/main/java/com/vison/webmvc/framework/DispatchServlet.java

@@ -1,14 +1,22 @@
 package com.vison.webmvc.framework;
 
 import java.io.IOException;
-import java.io.PrintWriter;
-import java.util.HashMap;
-import java.util.Map;
+import java.lang.reflect.Method;
+import java.lang.reflect.Parameter;
+import java.util.Set;
 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 javax.servlet.http.HttpSession;
+import org.reflections.Reflections;
+import org.reflections.scanners.MethodAnnotationsScanner;
+import org.reflections.util.ClasspathHelper;
+import org.reflections.util.ConfigurationBuilder;
+import org.reflections.util.FilterBuilder;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.LogManager;
 
 /**
  *
@@ -17,9 +25,7 @@
 @WebServlet(name = "DispatchServlet", urlPatterns = {"/"})
 public class DispatchServlet extends HttpServlet {
 
-    private Map<String, GetDispatcher> getMappings = new HashMap<>();
-    private Map<String, PostDispatcher> postMappings = new HashMap<>();
-    private ViewEngine viewEngine;
+    private static final Logger log = LogManager.getLogger(DispatchServlet.class.getName());
 
     @Override
     public void init() throws ServletException {
@@ -31,10 +37,81 @@ protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws Se
         resp.setContentType("text/html");
         resp.setCharacterEncoding("UTF-8");
         String path = req.getRequestURI().substring(req.getContextPath().length());
-        log(path);
-        resp.getWriter().write(path);
+        Object res = dispatch(path, req, resp);
+        String responseBody = this.handInvokeRes(res);
+        resp.getWriter().write(responseBody);
         resp.getWriter().flush();
-        // 根据路径查找GetDispatcher:
-        // 调用Controller方法获得返回值:
+    }
+
+    private Object dispatch(String path, HttpServletRequest request, HttpServletResponse response) {
+        Method method = this.getMaps(path);
+        log.info(method);
+        Object res = null;
+        if (method != null);
+        {
+            Parameter[] parameters = method.getParameters();
+            Object[] arguments = new Object[parameters.length];
+            for (int i = 0; i < parameters.length; i++) {
+                Parameter parameter = parameters[i];
+                log.info(parameter.getType());
+                Class<?> parameterClass = parameter.getType();
+                String parameterName = parameter.getName();
+                if (parameterClass == HttpServletRequest.class) {
+                    arguments[i] = request;
+                } else if (parameterClass == HttpServletResponse.class) {
+                    arguments[i] = response;
+                } else if (parameterClass == HttpSession.class) {
+                    arguments[i] = request.getSession();
+                } else if (parameterClass == int.class) {
+                    arguments[i] = Integer.valueOf(getOrDefault(request, parameterName, "0"));
+                } else if (parameterClass == long.class) {
+                    arguments[i] = Long.valueOf(getOrDefault(request, parameterName, "0"));
+                } else if (parameterClass == boolean.class) {
+                    arguments[i] = Boolean.valueOf(getOrDefault(request, parameterName, "false"));
+                } else if (parameterClass == String.class) {
+                    arguments[i] = getOrDefault(request, parameterName, "");
+                } else {
+                    throw new RuntimeException("Missing handler for type: " + parameterClass);
+                }
+            }
+            Object obj;
+            try {
+                obj = method.getDeclaringClass().getDeclaredConstructor().newInstance();
+                res = method.invoke(obj, arguments);
+            } catch (Exception e) {
+                log.error("方法invoke失败", e);
+            }
+        }
+        return res;
+    }
+
+    private String getOrDefault(HttpServletRequest request, String name, String defaultValue) {
+        String s = request.getParameter(name);
+        return s == null ? defaultValue : s;
+    }
+
+    private String handInvokeRes(Object obj) {
+        if (obj instanceof String) {
+            return (String) obj;
+        }
+        return "";
+    }
+
+    private Method getMaps(String path) {
+        String packageName = "com.vison.webmvc.controller";
+        ConfigurationBuilder config = new ConfigurationBuilder();
+        config.filterInputsBy(new FilterBuilder().includePackage(packageName));
+        config.addUrls(ClasspathHelper.forPackage(packageName));
+        config.setScanners(new MethodAnnotationsScanner());
+        Reflections f = new Reflections(config);
+        Set<Method> resources = f.getMethodsAnnotatedWith(GetMapping.class);
+
+        for (Method method : resources) {
+            GetMapping annotation = method.getAnnotation(GetMapping.class);
+            if (path.equals(annotation.path())) {
+                return method;
+            }
+        }
+        return null;
     }
 }

src/main/java/com/vison/webmvc/framework/GetDispatcher.java

@@ -0,0 +1,17 @@
+package com.vison.webmvc.framework;
+
+import java.lang.annotation.*;
+
+/**
+ *
+ * @author vison.cao <visonforcoding@gmail.com>
+ */
+@Target({ElementType.METHOD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+public @interface GetMapping {
+
+    String path() default "";
+
+}