自己实现一个简易的SpringMVC

上回实现了一个简易的Spring，那就顺便实现一些SpringMVC吧。由于有了上回的基础，这回实现比较快，晚饭前架构了一下，一晚上就写得差不多了。自己实现的架构比较简单，下面简单介绍一下。

源码下载：http://download.csdn.net/detail/jobsandczj/9844308

实现思路及工作流程：

定义一个DispatcherServlet，用来做请求入口。初始化时，去读取配置文件，获得Controller的包，然后“注入”Controller。SpringMVC它本身是有自己的IoC容器的，用来注入Controller以及它的组件，但IoC我在Spring里玩过了，这回就没有写依赖注入。但完事后发现其实也没省多少功夫，终归还是要扫包，解析的。

得到Controller后就构建Handler。让每个Handler与一个请求路径对应，我只定义了两种类型的Handler，一个是处理页面转发的，一个是返回Json数据的。每种Handler都有它的适配器，这就让Controller的方法设置参数少了很多约束，只要是request，response，session这仨家伙就行。

最后初始化适配器列表，以便在接收到请求后适配。

下面是Handler抽象类：

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;
}
}

下面这个是操作工具类，进行方法参数适配和适配器列表初始化

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("控制器参数错误");
}
}
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);

//实现了HandlerAdapter接口
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());
}
}

}

这是DispatcherServlet类，进行初始化和控制器调度，为了管理静态资源要进行servlet注册。
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);//获得扫描包
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 {

//获取请求路径
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);
}

}
}


这回还是有一些不足的，一是没实现IoC，当然这是自己偷懒。但还有一个不足就是，由于前端只支持JSP，所以View，Model这些也都没管。