手写springmvc流程

springmvc执行流程：

用户发送请求到前端控制器DispatchServletDispatchServlet收到请求调用HandleMapping处理器映射器处理器映射器返回handleExcutionChain通过处理器适配器调用具体的处理器调用处理器处理handle（即controller）返回modelAndViewDispatchServlet将返回的modelAndView交给ViewResolve处理返回View并进行视图渲染 springmvc加载过程

直接上代码 github地址 https://github.com/kkagr/spring.git 目录结构

1.首先新建maven项目 pom文件增加一个依赖

<dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.4</version> </dependency> </dependencies>

2.修改配载文件web.xml

<web-app> <display-name>SpringProject</display-name> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>com.liu.spring.servlet.LCHDispatchServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>application.properties</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> </web-app>

3。新建dispatchsetvlet

package com.liu.spring.servlet; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.net.URL; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Properties; import java.util.regex.Matcher; import java.util.regex.Pattern; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang3.StringUtils; import com.liu.spring.annotation.LCHAutorited; import com.liu.spring.annotation.LCHController; import com.liu.spring.annotation.LCHRequestMapping; import com.liu.spring.annotation.LCHService; import com.liu.spring.common.Handle; /** * @author kkagr * @version 创建时间：2018年5月6日 上午10:17:41 * 类说明 */ public class LCHDispatchServlet extends HttpServlet{ //所有的配载都放入到properties中 private Properties properties = new Properties(); private List<String> classNames = new ArrayList<String>(); private Map<String,Object> ioc = new HashMap<String, Object>(); //private Map<String,Object> handleMapping = new HashMap<String, Object>(); private List<Handle> hadleMapping = new ArrayList<Handle>(); //初始化阶段调用的方法 @Override public void init(ServletConfig config) throws ServletException { //1.加载配置文件 doLoadConfig(config.getInitParameter("contextConfigLocation").toString()); //2.根据配置文件扫描所有的相关类 doScanner(properties.get("scanPackage").toString()); //3.初始化所有相关类的实例，并且将其放入到ioc容器中，也就是map中 doInstance(); //4.自动实现依赖注入 doAutiWrited(); //5.初始化HandleMapping doInitHandlerMapping(); System.out.println("1"); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub this.doPost(req, resp); } //6.等待请求 //运行阶段执行的方法 @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException { try { doDispatch(req, resp); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); resp.getWriter().write("500 Exception"); } } private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws IOException, IllegalAccessException, IllegalArgumentException, InvocationTargetException { Handle handle = getHandler(req); if(handle == null){ resp.getWriter().write("404 NOT Found"); return; } Class<?>[] parameterTypes = handle.method.getParameterTypes(); Object[] paramValues = new Object[parameterTypes.length]; Map<String,String[]> params = req.getParameterMap(); for(Map.Entry<String, String[]> param:params.entrySet()){ String value = Arrays.toString(param.getValue()).replaceAll("\\[|\\]", "\\"); if(!handle.paramIndexMapping.containsKey(param.getKey())){continue;} int index = handle.paramIndexMapping.get(param.getKey()); paramValues[index] = handle.convert(parameterTypes[index],value); } int reqIndex = handle.paramIndexMapping.get(HttpServletRequest.class.getName()); paramValues[reqIndex] = req; int respIndex = handle.paramIndexMapping.get(HttpServletResponse.class.getName()); paramValues[respIndex] = resp; handle.method.invoke(handle.controller, paramValues); } private Handle getHandler(HttpServletRequest req) { String url = req.getRequestURI(); String contextPath = req.getContextPath(); url = url.replace(contextPath, "").replace("/+", "/"); for(Handle handle:hadleMapping){ Matcher matcher = handle.pattern.matcher(url); if(!matcher.matches()){continue;} return handle; } return null; } private void doLoadConfig(String location) { InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(location); try { properties.load(resourceAsStream); } catch (IOException e) { e.printStackTrace(); }finally { if(null!=resourceAsStream){ try { resourceAsStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } private void doScanner(String packageName) { //递归扫描 URL url = this.getClass().getClassLoader().getResource(packageName.replaceAll("\\.", "/")); File classDir = new File(url.getFile()); for(File file:classDir.listFiles()){ if(file.isDirectory()){ doScanner(packageName+"."+file.getName()); }else{ String className = packageName+"."+file.getName().replaceAll(".class", ""); classNames.add(className); } } } private void doInstance() { if(classNames.isEmpty()){ return; } try { for(String className:classNames){ Class<?> clazz = Class.forName(className); //接下来进入bean实例化，初始化ioc容器 //ioc规则 //1.keykey是用类名首字符小写 //2.如果用户自定义名字，那么就使用自定义名字 if(clazz.isAnnotationPresent(LCHController.class)){ String beanName = lowerFirstKey(clazz.getSimpleName()); ioc.put(beanName, clazz.newInstance()); }else if(clazz.isAnnotationPresent(LCHService.class)){ LCHService service = clazz.getAnnotation(LCHService.class); String beanName = service.value(); if(StringUtils.isBlank(beanName)){ beanName = lowerFirstKey(clazz.getSimpleName()); } ioc.put(beanName, clazz.newInstance()); //3.如果是接口，使用接口类型作为key Class<?>[] interfaces = clazz.getInterfaces(); for(Class<?> i:interfaces){ ioc.put(i.getName(), clazz.newInstance()); } }else{ continue; } } } catch (Exception e) { e.printStackTrace(); } } private void doAutiWrited() { if(ioc.isEmpty()){return;} for(Map.Entry<String, Object> entry:ioc.entrySet()){ //首先第一步提取所有的字段Field Field[] fields = entry.getValue().getClass().getDeclaredFields(); for(Field field:fields){ if(field.isAnnotationPresent(LCHAutorited.class)){ LCHAutorited autorited = field.getAnnotation(LCHAutorited.class); String beanName = autorited.value().trim(); if(StringUtils.isBlank(beanName)){ beanName = field.getType().getName(); } //不管public还是private都要强制注入 field.setAccessible(true); try { field.set(entry.getValue(), ioc.get(beanName)); } catch (IllegalArgumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } } private void doInitHandlerMapping() { if(ioc.isEmpty()){return;} for(Map.Entry<String, Object> entry:ioc.entrySet()){ Class<?> clazz = entry.getValue().getClass(); if(!clazz.isAnnotationPresent(LCHController.class)){continue;} String baseUrl = ""; if(clazz.isAnnotationPresent(LCHRequestMapping.class)){ LCHRequestMapping requestMapping = clazz.getAnnotation(LCHRequestMapping.class); baseUrl = requestMapping.value().trim(); } Method[] methods = clazz.getMethods(); for(Method method:methods){ if(!method.isAnnotationPresent(LCHRequestMapping.class)){continue;} LCHRequestMapping requestMapping = method.getAnnotation(LCHRequestMapping.class); String url = (baseUrl+requestMapping.value()).replaceAll("/+", "/"); Pattern pattern = Pattern.compile(url); hadleMapping.add(new Handle(entry.getValue(), method, pattern)); System.out.println("Mapping"+url+"method"+method); } } } private String lowerFirstKey(String str){ char[] chars = str.toCharArray(); chars[0]+=32; return chars.toString(); } }

hadler

package com.liu.spring.common; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import java.util.regex.Pattern; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.lang3.StringUtils; import com.liu.spring.annotation.LCHRequestMapping; import com.liu.spring.annotation.LCHRequestParam; /** * @author kkagr * @version 创建时间：2018年5月6日 下午1:36:48 * 类说明 */ public class Handle { public Object controller;//保存方法对应的实例 public Method method;//保存方法 public Pattern pattern; public Map<String,Integer> paramIndexMapping; public Handle(Object controller, Method method, Pattern pattern) { this.controller = controller; this.method = method; this.pattern = pattern; paramIndexMapping = new HashMap<String, Integer>(); paramIndexMapping(method); } private void paramIndexMapping(Method method2) { Annotation[][] pa = method.getParameterAnnotations(); for(int i = 0; i<pa.length; i++){ for(Annotation a:pa[i]){ if(a instanceof LCHRequestParam){ String paramName = ((LCHRequestParam) a).value(); if(StringUtils.isNotBlank(paramName)){ paramIndexMapping.put(paramName, i); } } } } Class<?>[] parameterTypes = method.getParameterTypes(); for(int i=0;i<parameterTypes.length; i++){ Class<?> type = parameterTypes[i]; if(type == HttpServletRequest.class ||type == HttpServletResponse.class){ paramIndexMapping.put(type.getName(), i); } } } public Object convert(Class<?> type, String value) { if(Integer.class == type){ return Integer.valueOf(value); } return value; } public Object getController() { return controller; } public void setController(Object controller) { this.controller = controller; } public Method getMethod() { return method; } public void setMethod(Method method) { this.method = method; } public Pattern getPattern() { return pattern; } public void setPattern(Pattern pattern) { this.pattern = pattern; } public Map<String, Integer> getParamIndexMapping() { return paramIndexMapping; } public void setParamIndexMapping(Map<String, Integer> paramIndexMapping) { this.paramIndexMapping = paramIndexMapping; } }