21. 用30个类手写V2.0版本之MVC实现
21. 用30个类手写V2.0版本之MVC实现
MVC顶层设计
一、请求调用
public class GPDispatcherServlet extends HttpServlet { //保存Controller中URL和Method的对应关系
private List<GPHandlerMapping> handlerMappings = new ArrayList<GPHandlerMapping>(); private Map<GPHandlerMapping,GPHandlerAdapter> handlerAdapters = new HashMap<GPHandlerMapping,GPHandlerAdapter>(); private List<GPViewResolver> viewResolvers = new ArrayList<GPViewResolver>(); //IoC容器的访问上下文
private GPApplicationContext applicationContext = null; @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doPost(req,resp);
} @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //6、根据URL委派给具体的调用方法
try {
doDispatch(req,resp);
} catch (Exception e) {
e.printStackTrace();// resp.getWriter().write("500 Exception,Detail: " + Arrays.toString(e.getStackTrace()));
Map<String,Object> model = new HashMap<String, Object>();
model.put("detail","500 Exception,Detail: ");
model.put("stackTrace",Arrays.toString(e.getStackTrace())); try {
processDispatchResult(req,resp,new GPModelAndView("500",model));
} catch (Exception exception) {
exception.printStackTrace();
}
}
} private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception { //1、根据URL 拿到对应的Handler
GPHandlerMapping handler = getHandler(req); if(null == handler){
processDispatchResult(req,resp,new GPModelAndView("404")); return;
} //2、根据HandlerMapping拿到HandlerAdapter
GPHandlerAdapter ha = getHandlerAdapter(handler); //3、根据HandlerAdapter拿到对应的ModelAndView
GPModelAndView mv = ha.handle(req,resp,handler);
//4、根据ViewResolver找到对应View对象
//通过View对象渲染页面，并返回
processDispatchResult(req,resp,mv);
} private void processDispatchResult(HttpServletRequest req, HttpServletResponse resp, GPModelAndView mv) throws Exception { if(null == mv){return;} if(this.viewResolvers.isEmpty()){return;} for (GPViewResolver viewResolver : this.viewResolvers) {
GPView view = viewResolver.resolveViewName(mv.getViewName());
view.render(mv.getModel(),req,resp); return;
}
} private GPHandlerAdapter getHandlerAdapter(GPHandlerMapping handler) { if(this.handlerAdapters.isEmpty()){ return null;}
GPHandlerAdapter ha = this.handlerAdapters.get(handler); return ha;
} private GPHandlerMapping getHandler(HttpServletRequest req) {
String url = req.getRequestURI();
String contextPath = req.getContextPath();
url = url.replaceAll(contextPath,"").replaceAll("/+","/"); for (GPHandlerMapping handlerMapping : this.handlerMappings) {
Matcher matcher = handlerMapping.getPattern().matcher(url); if(!matcher.matches()){ continue;} return handlerMapping;
} return null;
} @Override
public void init(ServletConfig config) throws ServletException {
applicationContext = new GPApplicationContext(config.getInitParameter("contextConfigLocation")); //========== MVC ==========
initStrategies(applicationContext);
System.out.println("GP Spring framework is init.");
} //初始化策略
protected void initStrategies(GPApplicationContext context) { //handlerMapping
initHandlerMappings(context); //初始化参数适配器
initHandlerAdapters(context); //初始化视图转换器
initViewResolvers(context);
} private void initViewResolvers(GPApplicationContext context) {
String templateRoot = context.getConfig().getProperty("templateRoot");
String templateRootPath = this.getClass().getClassLoader().getResource(templateRoot).getFile();
File templateRootDir = new File(templateRootPath); for (File file : templateRootDir.listFiles()) { this.viewResolvers.add(new GPViewResolver(templateRoot));
}
} private void initHandlerAdapters(GPApplicationContext context) { for (GPHandlerMapping handlerMapping : handlerMappings) { this.handlerAdapters.put(handlerMapping,new GPHandlerAdapter());
}
} private void initHandlerMappings(GPApplicationContext context) { if(this.applicationContext.getBeanDefinitionCount() == 0 ){ return; } for (String beanName : this.applicationContext.getBeanDefinitionNames()) {
Object instance = applicationContext.getBean(beanName);
Class<?> clazz = instance.getClass(); if(!clazz.isAnnotationPresent(GPController.class)){ continue; }
String baseUrl = ""; if(clazz.isAnnotationPresent(GPRequestMapping.class)){
GPRequestMapping requestMapping = clazz.getAnnotation(GPRequestMapping.class);
baseUrl = requestMapping.value();
} //只迭代public方法
for (Method method : clazz.getMethods()) { if(!method.isAnnotationPresent(GPRequestMapping.class)){ continue; }
GPRequestMapping requestMapping = method.getAnnotation(GPRequestMapping.class); // //demo//query
String regex = ("/" + baseUrl + "/" + requestMapping.value())
.replaceAll("\\*",".*")
.replaceAll("/+","/");
Pattern pattern = Pattern.compile(regex);
handlerMappings.add(new GPHandlerMapping(pattern,instance,method));
System.out.println("Mapped : " + regex + " --> " + method);
}
}
}
}二、请求映射
public class GPHandlerMapping { private Object controller; //保存方法应对的实例
protected Method method; //保存映射的方法
protected Pattern pattern; //URL 的正则匹配
public GPHandlerMapping(Pattern pattern,Object controller,Method method) { this.controller = controller; this.method = method; this.pattern = pattern;
} public Method getMethod() { return method;
} public Pattern getPattern() { return pattern;
} public Object getController() { return controller;
}
}三、请求方法适配器
public class GPHandlerAdapter { public GPModelAndView handle(HttpServletRequest req, HttpServletResponse resp, GPHandlerMapping handler) throws Exception {
Method method = handler.getMethod(); //1、先把形参的位置和参数名字建立映射关系，并且缓存下来
Map<String,Integer> paramIndexMapping = new HashMap<String, Integer>();
Annotation[][] pa = method.getParameterAnnotations(); for (int i = 0; i < pa.length; i ++) { for (Annotation a : pa[i]) { if(a instanceof GPRequestParam){
String paramName = ((GPRequestParam) a).value(); if(!"".equals(paramName.trim())){
paramIndexMapping.put(paramName,i);
}
}
}
}
Class<?> [] paramTypes = method.getParameterTypes(); for (int i = 0; i < paramTypes.length; i++) {
Class<?> type = paramTypes[i]; if(type == HttpServletRequest.class || type == HttpServletResponse.class){
paramIndexMapping.put(type.getName(),i);
}
} //2、根据参数位置匹配参数名字，从url中取到参数名字对应的值
Object[] paramValues = new Object[paramTypes.length]; //http://localhost/demo/query?name=Tom&name=Tomcat&name=Mic
Map<String,String[]> params = req.getParameterMap(); for (Map.Entry<String, String[]> param : params.entrySet()) {
String value = Arrays.toString(param.getValue())
.replaceAll("\\[|\\]","")
.replaceAll("\\s",""); if(!paramIndexMapping.containsKey(param.getKey())){continue;} int index = paramIndexMapping.get(param.getKey()); //涉及到类型强制转换
paramValues[index] = caseStringValue(value,paramTypes[index]);
} if(paramIndexMapping.containsKey(HttpServletRequest.class.getName())){ int index = paramIndexMapping.get(HttpServletRequest.class.getName());
paramValues[index] = req;
} if(paramIndexMapping.containsKey(HttpServletResponse.class.getName())){ int index = paramIndexMapping.get(HttpServletResponse.class.getName());
paramValues[index] = resp;
}
Object result = method.invoke(handler.getController(),paramValues); if(result == null || result instanceof Void){ return null;} boolean isModelAndView = handler.getMethod().getReturnType() == GPModelAndView.class; if(isModelAndView){ return (GPModelAndView) result;
} return null;
} private Object caseStringValue(String value, Class<?> paramType) { if(String.class == paramType){ return value;
} if(Integer.class == paramType){ return Integer.valueOf(value);
}else if(Double.class == paramType){ return Double.valueOf(value);
}else { if(value != null){ return value;
} return null;
}
}
}四、页面数据封装
public class GPModelAndView { private String viewName; private Map<String,?> model; public GPModelAndView(String viewName) { this.viewName = viewName;
} public GPModelAndView(String viewName, Map<String, ?> model) { this.viewName = viewName; this.model = model;
} public String getViewName() { return viewName;
} public Map<String, ?> getModel() { return model;
}
}五、试图解析器
public class GPViewResolver { //.vm .ftl .jsp .gp .tom
private final String DEFAULT_TEMPLATE_SUFFIX = ".html"; private File templateRootDir; public GPViewResolver(String templateRoot) {
String templateRootPath = this.getClass().getClassLoader().getResource(templateRoot).getFile();
templateRootDir = new File(templateRootPath);
} public GPView resolveViewName(String viewName) { if(null == viewName || "".equals(viewName.trim())){return null;}
viewName = viewName.endsWith(DEFAULT_TEMPLATE_SUFFIX) ? viewName : (viewName + DEFAULT_TEMPLATE_SUFFIX);
File templateFile = new File((templateRootDir.getPath() + "/" + viewName)
.replaceAll("/+","/")); return new GPView(templateFile);
}
}六、自定义引擎模板
public class GPView { private File viewFile; public GPView(File templateFile) { this.viewFile = templateFile;
} public void render(Map<String,?> model, HttpServletRequest req, HttpServletResponse resp) throws Exception { //无反射，不框架
//无正则，不架构
StringBuffer sb = new StringBuffer();
RandomAccessFile ra = new RandomAccessFile(this.viewFile,"r");
String line = null; while (null != (line = ra.readLine())){
line = new String(line.getBytes("iso-8859-1"),"utf-8");
Pattern pattern = Pattern.compile("￥\\{[^\\}]+\\}",Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(line); while (matcher.find()){ // ￥{teacher}
String paramName = matcher.group();
paramName = paramName.replaceAll("￥\\{|\\}","");
Object paramValue = model.get(paramName); if(null == paramValue){continue;}
line = matcher.replaceFirst(makeStringForRegExp(paramValue.toString()));
matcher = pattern.matcher(line);
}
sb.append(line);
}
resp.setCharacterEncoding("utf-8");
resp.getWriter().write(sb.toString());
} //处理特殊字符
public static String makeStringForRegExp(String str) { return str.replace("\\", "\\\\").replace("*", "\\*")
.replace("+", "\\+").replace("|", "\\|")
.replace("{", "\\{").replace("}", "\\}")
.replace("(", "\\(").replace(")", "\\)")
.replace("^", "\\^").replace("$", "\\$")
.replace("[", "\\[").replace("]", "\\]")
.replace("?", "\\?").replace(",", "\\,")
.replace(".", "\\.").replace("&", "\\&");
}
}柒徳咙咚呛 : Just Do It 资源地址：https://www.cnblogs.com/Andy-15811517571/