servlet-url-map

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class AServlet extends HttpServlet {
	private Map<String, String> urlHandlerMethods = new ConcurrentHashMap<String, String>();

	private String baseUrl = "";

    private Object methodInvoke(Object object, String methodName,Class<?>... parameterTypes) {
        try {
            Class<? extends Object> classInfo = object.getClass();
            Method method = classInfo.getMethod(methodName,parameterTypes);
            Object result = method.invoke(object);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "error";
    }


	@Override
	public void init() throws ServletException {
        String baseUrlTmp = this.getInitParameter("baseUrl");
        if(baseUrlTmp != null){
            this.baseUrl = baseUrlTmp;
        }
        ServletContext servletContext = this.getServletContext();
        String contextPath = servletContext.getContextPath();
        String servletInfo = this.getServletInfo();
         ServletConfig config = getServletConfig();
        Class<? extends EleDocServlet> aClass = this.getClass();
        Method[] declaredMethods = aClass.getDeclaredMethods();
        for (Method method : declaredMethods) {
            UrlMapping methodUrlMapping = method.getDeclaredAnnotation(UrlMapping.class);
            if (methodUrlMapping != null) {
                String methodUrl = this.baseUrl + methodUrlMapping.value();
                urlHandlerMethods.put(methodUrl, method.getName());
            }
        }
	}

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String requestURI = request.getRequestURI();
        String methodName = urlHandlerMethods.get(requestURI);
		if (methodName == null) {
            response.getWriter().println("404_not_found");
			return;
		}

        Object result = methodInvoke(this, methodName, request.getClass(), response.getClass());
        response.getWriter().println(result);
	}

	@UrlMapping("/index")
	public String test(HttpServletRequest request, HttpServletResponse response){
        return "ok";
    }

}

@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@interface UrlMapping {
    String value() default "";
}