請求轉發器

用于處理用戶發送給的請求。

我們需要一個Servlet來處理所有的請求
這是HttpServlet的處理請求的service函數源碼

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String method = req.getMethod();long errMsg;if(method.equals("GET")) {errMsg = this.getLastModified(req);if(errMsg == -1L) {this.doGet(req, resp);} else {long ifModifiedSince = req.getDateHeader("If-Modified-Since");if(ifModifiedSince < errMsg) {this.maybeSetLastModified(resp, errMsg);this.doGet(req, resp);} else {resp.setStatus(304);}}} else if(method.equals("HEAD")) {errMsg = this.getLastModified(req);this.maybeSetLastModified(resp, errMsg);this.doHead(req, resp);} else if(method.equals("POST")) {this.doPost(req, resp);} else if(method.equals("PUT")) {this.doPut(req, resp);} else if(method.equals("DELETE")) {this.doDelete(req, resp);} else if(method.equals("OPTIONS")) {this.doOptions(req, resp);} else if(method.equals("TRACE")) {this.doTrace(req, resp);} else {String errMsg1 = lStrings.getString("http.method_not_implemented");Object[] errArgs = new Object[]{method};errMsg1 = MessageFormat.format(errMsg1, errArgs);resp.sendError(501, errMsg1);}}

我們可以知道 ，這個是通過方法的類型不同進行轉向不同的函數進行出處理。
而我們需要把
get:customer_show
post:customer_create
暫時先不討論符合restful的url
我們可以設置一個注解@Action用來和spring的RequestMapping方法一樣
但是我們這個看上去不像RequestMapping中那樣的繁瑣
具體可參照smart-framework 點擊跳轉oschina文檔首頁

• 先預處理request與handler的映射
  
  • 加載帶有Controller注解的類
  • 掃描Action注解來獲取到get:customer_show這個屬性的值
  • 通過正則表達式\\w:/\\w*匹配
  • 分割字符串
  • 添加一個handler用于接受請求并執行方法，返回結果
  • 添加request（格式請求方法類型：請求路徑）-handler映射

/*** Created by xueaohui on 2016/6/22.*/ public final class ControllerHelper {/*** 用來存放請求與處理器的映射關系(Action Map)*/private static final Map<Request,Handler> ACTION_MAP = new HashMap<Request, Handler>();static {Set<Class<?>> controllerClassSet = ClassHelper.getControllerClassSet();if(CollectionUtil.isNotEmpty(controllerClassSet)){for(Class<?> controllerClass : controllerClassSet){Method[] methods = controllerClass.getMethods();if(ArrayUtil.isNotEmpty(methods)) {for (Method method : methods) {//如果這個方法被Action注釋了if(method.isAnnotationPresent(Action.class)){Action action = method.getAnnotation(Action.class);//獲取Action的屬性值String mapping = action.value();//驗證URL 如get:customer_list post:customer_updateif(mapping.matches("\\w+:/\\w*")){String[] array = mapping.split(":");if(ArrayUtil.isNotEmpty(array)){String requestMethod = array[0];String requestPath = array[1];Request request = new Request(requestMethod,requestPath);Handler handler = new Handler(controllerClass,method);//初始化handlerACTION_MAP.put(request,handler);}}}}}}}}/*** 獲取Handler*/public static Handler getHandler(String requestMethod , String requestPath){Request request = new Request(requestMethod,requestPath);return ACTION_MAP.get(request);} }

獲取了我們就可以直接service方法寫業務邏輯處理請求了
返回結果 有兩種方式
json 和 jsp頁面

package org.smart4j.framework;import java.io.IOException; import java.io.PrintWriter; import java.lang.reflect.Method; import java.util.Map; import javax.servlet.ServletConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRegistration; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;import org.smart4j.framework.bean.Data; import org.smart4j.framework.bean.Handler; import org.smart4j.framework.bean.Param; import org.smart4j.framework.bean.View; import org.smart4j.framework.helper.BeanHelper; import org.smart4j.framework.helper.ConfigHelper; import org.smart4j.framework.helper.ControllerHelper; import org.smart4j.framework.helper.RequestHelper; import org.smart4j.framework.helper.ServletHelper; import org.smart4j.framework.helper.UploadHelper; import org.smart4j.framework.util.JsonUtil; import org.smart4j.framework.util.ReflectionUtil; import org.smart4j.framework.util.StringUtil;/*** 請求轉發器**/ @WebServlet(urlPatterns = "/*", loadOnStartup = 0) public class DispatcherServlet extends HttpServlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {HelpLoader.init();ServletContext servletContext = servletConfig.getServletContext();registerServlet(servletContext);UploadHelper.init(servletContext);}private void registerServlet(ServletContext servletContext) {// 用 JspServlet 映射所有 JSP 請求ServletRegistration jspServlet = servletContext.getServletRegistration("jsp");jspServlet.addMapping("/index.jsp");jspServlet.addMapping(ConfigHelper.getAppJSpPath() + "*");// 用 DefaultServlet 映射所有靜態資源ServletRegistration defaultServlet = servletContext.getServletRegistration("default");defaultServlet.addMapping("/favicon.ico");defaultServlet.addMapping(ConfigHelper.getAppAssetPath() + "*");}@Overridepublic void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {ServletHelper.init(request, response);try {String requestMethod = request.getMethod().toLowerCase();String requestPath = request.getPathInfo();Handler handler = ControllerHelper.getHandler(requestMethod, requestPath);if (handler != null) {Class<?> controllerClass = handler.getControllerClass();Object controllerBean = BeanHelper.getBean(controllerClass);Param param;if (UploadHelper.isMultipart(request)) {param = UploadHelper.createParam(request);} else {param = RequestHelper.createParam(request);}Object result;Method actionMethod = handler.getActionMethod();if (param.isEmpty()) {result = ReflectionUtil.invokeMethod(controllerBean, actionMethod);} else {result = ReflectionUtil.invokeMethod(controllerBean, actionMethod, param);}if (result instanceof View) {handleViewResult((View) result, request, response);} else if (result instanceof Data) {handleDataResult((Data) result, response);}}} finally {ServletHelper.destroy();}}/*** 轉發返回頁面的請求*/private void handleViewResult(View view, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {String path = view.getPath();if (StringUtil.isNotEmpty(path)) {if (path.startsWith("/")) {response.sendRedirect(request.getContextPath() + path);} else {Map<String, Object> model = view.getModel();for (Map.Entry<String, Object> entry : model.entrySet()) {request.setAttribute(entry.getKey(), entry.getValue());}request.getRequestDispatcher(ConfigHelper.getAppJSpPath() + path).forward(request, response);}}}/*** 轉發返回json數據的請求*/private void handleDataResult(Data data, HttpServletResponse response) throws IOException {Object model = data.getModel();if (model != null) {response.setContentType("application/json");response.setCharacterEncoding("UTF-8");PrintWriter writer = response.getWriter();String json = JsonUtil.toJson(model);writer.write(json);writer.flush();writer.close();}} }

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