自己實現一個簡易的SpringMVC
阿新 • • 發佈:2019-02-16
上回實現了一個簡易的Spring,那就順便實現一些SpringMVC吧。由於有了上回的基礎,這回實現比較快,晚飯前架構了一下,一晚上就寫得差不多了。自己實現的架構比較簡單,下面簡單介紹一下。
實現思路及工作流程:
定義一個DispatcherServlet,用來做請求入口。初始化時,去讀取配置檔案,獲得Controller的包,然後“注入”Controller。SpringMVC它本身是有自己的IoC容器的,用來注入Controller以及它的元件,但IoC我在Spring裡玩過了,這回就沒有寫依賴注入。但完事後發現其實也沒省多少功夫,終歸還是要掃包,解析的。
得到Controller後就構建Handler。讓每個Handler與一個請求路徑對應,我只定義了兩種型別的Handler,一個是處理頁面轉發的,一個是返回Json資料的。每種Handler都有它的介面卡
最後初始化介面卡列表,以便在接收到請求後適配。
下面是Handler抽象類:
package MySpringMVC.springmvc; import java.lang.reflect.Method; /** * Created by 10033 on 2017/5/16. */ public abstract class Handler { protected Method method; protected Object controller; protected Class[] params; protected RequestMethod requestMethod; public Handler(Method method, Object controller, Class[] params, RequestMethod requestMethod) { this.method = method; this.controller = controller; this.params = params; this.requestMethod = requestMethod; } public Method getMethod() { return method; } public void setMethod(Method method) { this.method = method; } public Object getController() { return controller; } public void setController(Object controller) { this.controller = controller; } public Class[] getParams() { return params; } public void setParams(Class[] params) { this.params = params; } public RequestMethod getRequestMethod() { return requestMethod; } public void setRequestMethod(RequestMethod requestMethod) { this.requestMethod = requestMethod; } }
下面這個是操作工具類,進行方法引數適配和介面卡列表初始化
這是DispatcherServlet類,進行初始化和控制器排程,為了管理靜態資源要進行servlet註冊。package MySpringMVC.utils; import MySpringMVC.springmvc.ClasspathPackageScanner; import MySpringMVC.springmvc.HandlerAdapter; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; import java.util.List; /** * Created by 10033 on 2017/5/16. */ public class OperationUtil { private static final Logger logger = LoggerFactory.getLogger(OperationUtil.class); private static final String ADAPTER_PACKAGE="MySpringMVC.springmvc"; public static int makeObjectsByClasses (Class[] classes, Object[] objects, HttpServletRequest request, HttpServletResponse response) throws Exception { int cou=0; for(Class cla:classes) { if(cla==HttpServletRequest.class) { objects[cou++]=request; } else if(cla==HttpServletResponse.class) { objects[cou++]=response; } else if(cla==HttpSession.class) { objects[cou++]=request.getSession(); } else { throw new Exception("控制器引數錯誤"); } } return cou; } public static void initHandlerAdapterList(List<HandlerAdapter> list) { try { List<String> classStringList=new ClasspathPackageScanner(ADAPTER_PACKAGE).getFullyQualifiedClassNameList(); for(String s:classStringList) { Class cla=Class.forName(s); //實現了HandlerAdapter介面 if (HandlerAdapter.class.isAssignableFrom(cla)) { Object obj=cla.newInstance(); list.add((HandlerAdapter) obj); } } } catch (IOException e) { logger.error(e.getMessage()); } catch (ClassNotFoundException e) { logger.error(e.getMessage()); } catch (IllegalAccessException e) { logger.error(e.getMessage()); } catch (InstantiationException e) { logger.error(e.getMessage()); } } }
package MySpringMVC.springmvc;
import MySpringMVC.utils.OperationUtil;
import MySpringMVC.utils.PropertiesReaderUtil;
import MySpringMVC.utils.StringUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Created by 10033 on 2017/5/16.
*/
public class DispatcherServlet extends HttpServlet {
private static final Logger logger = LoggerFactory.getLogger(DispatcherServlet.class);
private String configName;
private Map<String, String> configMap;
private static final String SCAN_PACK="scan.package";
private static final String VIEWPATH_STATIC="viewpath.static";
private HandlerMap handleMap;
private List<HandlerAdapter> handlerAdapters = new ArrayList<HandlerAdapter>();
//初始化
public void init(String configName) throws ServletException {
super.init();
// configName=getInitParameter("contextConfigLocationName");
configMap= PropertiesReaderUtil.getProperties(configName);
String packages=configMap.get(SCAN_PACK);//獲得掃描包
DispatchHelper.setMap(configMap);
try {
List<String> list=new ClasspathPackageScanner(packages).getFullyQualifiedClassNameList();
handleMap=new HandlerMap(list);
} catch (IOException e) {
logger.error(e.getMessage());
}
OperationUtil.initHandlerAdapterList(handlerAdapters);
}
@Override
public void init(ServletConfig config) throws ServletException {
init(config.getInitParameter("contextConfigLocationName"));
ServletContext servletContext=config.getServletContext();
/*ServletRegistration servletRegistration = servletContext.getServletRegistration("jsp");
servletRegistration.addMapping("/WEB-INF/jsps*//*");*/
ServletRegistration servletRegistration2 = servletContext.getServletRegistration("default");
String[] staticString=configMap.get(VIEWPATH_STATIC).split(";");
for(int i=0;i<staticString.length;i++) {
servletRegistration2.addMapping(staticString[i].toLowerCase()+"/*");
}
}
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//獲取請求路徑
String requestUrl=StringUtil.getRequestURL(req);
Handler handler=handleMap.getHandler(requestUrl,req.getMethod());
if(null!=handler) {
for(HandlerAdapter handlerAdapter:handlerAdapters) {
if(handlerAdapter.support(handler)) {
handlerAdapter.setHandler(handler);
handlerAdapter.execute(req,resp);
break;
}
}
}else {
resp.sendError(HttpServletResponse.SC_NOT_FOUND);
}
}
}
這回還是有一些不足的,一是沒實現IoC,當然這是自己偷懶。但還有一個不足就是,由於前端只支援JSP,所以View,Model這些也都沒管。