徒手编写Spring的初始化之山寨版IOC容器
建一个简单的web工程。
工程目录：
配置application.properties
scanPackage=com.gys.demo #扫描该包下的类
编写注解
package annotation; import java.lang.annotation.*; @Target({ElementType.FIELD}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface GysAutowired { String value() default ""; }
package annotation; import java.lang.annotation.*; @Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface GysController { String value() default ""; }
package annotation; import java.lang.annotation.*; @Target({ElementType.TYPE,ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface GysRequestMapping { String value() default ""; }
package annotation; import java.lang.annotation.*; @Target({ElementType.PARAMETER}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface GysRequestParam { String value() default ""; }
package annotation; import java.lang.annotation.*; @Target({ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface GysService { String value() default ""; }
service编写
package com.gys.demo.service; public interface IDemoService { String get(String name); }
package com.gys.demo.service.impl; import annotation.GysService; import com.gys.demo.service.IDemoService; @GysService public class DemoService implements IDemoService { @Override public String get(String name) { return "<h1>Hello,"+name+"</h1>"; } }
controller代码
package com.gys.demo.controller; import annotation.GysAutowired; import annotation.GysController; import annotation.GysRequestMapping; import annotation.GysRequestParam; import com.gys.demo.service.IDemoService; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.IOException; @GysController @GysRequestMapping("/demo") public class DemoController { @GysAutowired private IDemoService iDemoService; @GysRequestMapping("/query") public void query(HttpServletRequest request,HttpSession session,HttpServletResponse response, @GysRequestParam("name") String name) throws IOException { System.out.println("query.............."); String res=iDemoService.get(name); response.getWriter().write(res); } }
新建Servlet，配置servlet
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd" > <web-app> <display-name>Archetype Created Web Application</display-name> <servlet> <servlet-name>gysMvc</servlet-name> <servlet-class>servlet.GysDispatcherServlet</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>gysMvc</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> </web-app>
核心代码servlet,代码有点长，直接折叠了。
package servlet; import annotation.*; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.lang.annotation.Annotation; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.net.URL; import java.util.*; import java.util.regex.Matcher; import java.util.regex.Pattern; public class GysDispatcherServlet extends HttpServlet { private Properties contextConfig = new Properties(); //包+类文件名（去除.class后缀） private List<String> classNames = new ArrayList<>(); //名称，对象 private Map<String, Object> ioc = new HashMap<>(); //url,方法 private List<Handler> handlerMapping=new ArrayList<>(); @Override public void init(ServletConfig config) throws ServletException { //1.加载配置文件 doLoadConfig(config.getInitParameter("contextConfigLocation")); //2.扫描相关类 doScanner(contextConfig.getProperty("scanPackage")); //3.初始化扫描的类，并放入ioc容器 doInstance(); //完成依赖注入 doAutowired(); //url和method的一对一关系 initHandlerMapping(); System.out.println("servlet init finsh=================="); } @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 { try { req.setCharacterEncoding("utf-8"); resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html;charset=utf-8"); //具体处理逻辑 doDispatch(req, resp); } catch (InvocationTargetException e) { e.printStackTrace(); } catch (IllegalAccessException e) { resp.getWriter().write("500 Exception" + Arrays.toString(e.getStackTrace())); } } private void doDispatch(HttpServletRequest request, HttpServletResponse response) throws IOException, InvocationTargetException, IllegalAccessException { Handler handler=getHandler(request); if(handler==null){ response.getWriter().write("404 对不起没有您要的页面资源"); return; } //参数类型数组 Class<?>[] parameterTypes=handler.method.getParameterTypes(); //参数数组 Object[] paramValues=new Object[parameterTypes.length]; Map<String, String[]> parameterMap = request.getParameterMap(); for(Map.Entry<String,String[]> entry:parameterMap.entrySet()){ //数组中的[[ 和 ]] 替换 String value=Arrays.toString(entry.getValue()).replaceAll("\\[|\\]",""); if(!handler.paramIndexMapping.containsKey(entry.getKey())){ continue; } int index=handler.paramIndexMapping.get(entry.getKey()); value=new String(value.getBytes("iso-8859-1"), "utf-8"); paramValues[index]=convert(parameterTypes[index],value); } //如果方法参数是request if(handler.paramIndexMapping.containsKey(HttpServletRequest.class.getName())){ int reqIndex=handler.paramIndexMapping.get(HttpServletRequest.class.getName()); paramValues[reqIndex]=request; } //如果方法参数是response if(handler.paramIndexMapping.containsKey(HttpServletResponse.class.getName())){ int reqIndex=handler.paramIndexMapping.get(HttpServletResponse.class.getName()); paramValues[reqIndex]=response; } //如果方法参数是session if(handler.paramIndexMapping.containsKey(HttpSession.class.getName())){ int reqIndex=handler.paramIndexMapping.get(HttpSession.class.getName()); paramValues[reqIndex]=request.getSession(); } //利用反射调用mapping标识的方法 Object returnValue=handler.method.invoke(handler.controller,paramValues); if(returnValue==null||returnValue instanceof Void){ return; } //向浏览器输出类容 response.getWriter().write(returnValue.toString()); } private void doLoadConfig(String contextConfigLocation) { InputStream is = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation); try { contextConfig.load(is); } catch (IOException e) { e.printStackTrace(); } finally { if (is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } } } private void doScanner(String scanPackage) { String xgScanPackage = scanPackage.replaceAll("\\.", "/"); URL url = this.getClass().getClassLoader().getResource("/" + xgScanPackage); String path = url.getFile(); File classDir = new File(path); for (File file : classDir.listFiles()) { if (file.isDirectory()) { doScanner(scanPackage + "." + file.getName()); } else { if (!file.getName().endsWith(".class")) { continue; } //所有类的文件路径+包名 String clazzName = (scanPackage + "." + file.getName()).replace(".class", ""); classNames.add(clazzName); } } } private void doInstance() { if (classNames.isEmpty()) { return; } try { for (String className : classNames) { Class<?> clazz = Class.forName(className); //controller注解 if(clazz.isAnnotationPresent(GysController.class)){ Object instance=clazz.newInstance(); String beanName=toLowerFirstCase(clazz.getSimpleName()); //类名,实例对象 ioc.put(beanName,instance); }else if(clazz.isAnnotationPresent(GysService.class)){//service注解 Object instance=clazz.newInstance(); GysService gysService=clazz.getAnnotation(GysService.class); String beanName=gysService.value(); //没规定类名 if("".equals(beanName.trim())){ //类名首字母小写 beanName=toLowerFirstCase(clazz.getSimpleName()); } //类名，对象 ioc.put(beanName,instance); //循环接口 for(Class inter:clazz.getInterfaces()){ //接口长类名，子类实现对象 ioc.put(inter.getName(),instance); } }else{ continue; } } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InstantiationException e) { e.printStackTrace(); } } private void doAutowired(){ if(ioc.isEmpty()){ return; } //循环ioc容器 for (Map.Entry<String,Object> entry:ioc.entrySet()) { //获取所有的字段 Field[] fields = entry.getValue().getClass().getDeclaredFields(); for(Field field:fields){ field.setAccessible(true); //判断是否有有依赖注入 if (!field.isAnnotationPresent(GysAutowired.class)) { continue; } GysAutowired gysAutowired = field.getAnnotation(GysAutowired.class); //获取依赖名称 String beanName=gysAutowired.value().trim(); if (beanName.isEmpty()) {//未定义依赖名称 //获取字段类型长路径名 Class type= field.getType(); if (type.isInterface()) {//接口用长路径名 beanName=type.getName(); }else{//实体类用类名 beanName=toLowerFirstCase(type.getSimpleName()); } } try { //设置字段值，实现依赖注入 field.set(entry.getValue(),ioc.get(beanName)); } catch (IllegalAccessException e) { e.printStackTrace(); } } } } private void initHandlerMapping(){ if(ioc.isEmpty()){ return; } for(Map.Entry<String,Object> entry:ioc.entrySet()){ Class<?> clazz=entry.getValue().getClass(); if(!clazz.isAnnotationPresent(GysController.class)){ continue; } String url=""; if(clazz.isAnnotationPresent(GysRequestMapping.class)){ GysRequestMapping gysRequestMapping=clazz.getAnnotation(GysRequestMapping.class); url=gysRequestMapping.value(); } for(Method method:clazz.getMethods()){ if(!method.isAnnotationPresent(GysRequestMapping.class)){ continue; } GysRequestMapping gysRequestMapping=method.getAnnotation(GysRequestMapping.class); String regex=url+gysRequestMapping.value(); Pattern pattern=Pattern.compile(regex); handlerMapping.add(new Handler(pattern,entry.getValue(),method)); System.out.println("Mapped："+url+","+method); } } } //首字母小写 private String toLowerFirstCase(String simpleName){ char[] chars=simpleName.toCharArray(); chars[0]+=32; return String.valueOf(chars); } private class Handler{ protected Object controller;//保存方法对应的实例 protected Method method;//保存映射方法 protected Pattern pattern; protected Map<String,Integer> paramIndexMapping;//参数顺序 public Handler(Pattern pattern,Object controller, Method method) { this.controller = controller; this.method = method; this.pattern = pattern; this.paramIndexMapping = new HashMap<>(); putParamIndexMapping(this.method); } private void putParamIndexMapping(Method method){ Annotation[][] annotations=method.getParameterAnnotations(); for(int i=0;i<annotations.length;i++){ for(Annotation annotation:annotations[i]){ if(annotation instanceof GysRequestParam){ String paranName=((GysRequestParam) annotation).value(); if(!paranName.trim().isEmpty()){ paramIndexMapping.put(paranName,i); } } } } Class<?>[] paramsTypes=method.getParameterTypes(); for(int i=0;i<paramsTypes.length;i++){ Class<?> type=paramsTypes[i]; if(type==HttpServletRequest.class||type==HttpServletResponse.class||type==HttpSession.class){ paramIndexMapping.put(type.getName(),i); } } } } private Handler getHandler(HttpServletRequest request){ if(handlerMapping.isEmpty()){ return null; } String url=request.getRequestURI(); String contextPath=request.getContextPath(); url=url.replace(contextPath,""); for(Handler handler:handlerMapping){ Matcher matcher=handler.pattern.matcher(url); if(!matcher.matches()){ continue; } return handler; } return null; } //由于HTTP基于字符串协议，url传过来的参数都是String类型的; private Object convert(Class<?> type,String value){ if(Integer.class==type){ return Integer.valueOf(value); }else if(Double.class==type){ return Double.valueOf(value); } //....... return value; } }
运行项目
