十二：手写初体验Spring V1.0版本
1.1.实现思路
先来介绍一下Mini版本的Spring基本实现思路,如下图所示:
1.2.自定义配置 application.properties 文件
为了解析方便,我们用application.properties来代替application.xml文 件 ，具体配置内容如下:
scanPackage=com.gupaoedu.demo
1.3.配置web.xml文件
大家都知道,所有依赖于web容器的项目,都是从读取web.xml文件开始的。我们先配置好web.xml
中的内容。
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:javaee="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
version="2.4">
<display-name>Gupao Web Application</display-name>
<servlet>
<servlet-name>gpmvc</servlet-name>
<servlet-class>com.gupaoedu.mvcframework.v2.servlet.GPDispatchServlet</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>gpmvc</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
</web-app>
其中GPDispatcherServlet是有自己模拟Spring实现的核心功能类。
1.4.自定义 Annotation
@GPService 注解:
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPService {
String value() default "";
}
@GPAutowired 注 解 ：
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPAutowired {
String value() default "";
}
@GPController 注 解 ：
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPController {
String value() default "";
}
@GPRequestMapping 注 解 ：
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPRequestMapping {
String value() default "";
}
@GPRequestParam 注 解 ：
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface GPRequestParam {
String value() default "";
}
1.5.配置 Annotation
配置业务实现类DemoService :
/**
* 核心业务逻辑
*/
@GPService
public class DemoService implements IDemoService{
public String get(String name) {
return "My name is " + name + ",from service.";
}
}
配置请求入口类DemoAction :
//虽然，用法一样，但是没有功能
@GPController
@GPRequestMapping("/demo")
public class DemoAction {
@GPAutowired private IDemoService demoService;
@GPRequestMapping("/query")
public void query(HttpServletRequest req, HttpServletResponse resp,
@GPRequestParam("name") String name){
String result = demoService.get(name);
// String result = "My name is " + name;
try {
resp.getWriter().write(result);
} catch (IOException e) {
e.printStackTrace();
}
}
@GPRequestMapping("/add")
public void add(HttpServletRequest req, HttpServletResponse resp,
@GPRequestParam("a") Integer a, @GPRequestParam("b") Integer b){
try {
resp.getWriter().write(a + "+" + b + "=" + (a + b));
} catch (IOException e) {
e.printStackTrace();
}
}
@GPRequestMapping("/sub")
public void add(HttpServletRequest req, HttpServletResponse resp,
@GPRequestParam("a") Double a, @GPRequestParam("b") Double b){
try {
resp.getWriter().write(a + "-" + b + "=" + (a - b));
} catch (IOException e) {
e.printStackTrace();
}
}
@GPRequestMapping("/remove")
public String remove(@GPRequestParam("id") Integer id){
return "" + id;
}
}
---结束
1.6.容器初始化实现V1版本
所有的核心逻辑全部写在一个init()方法中。
public class GPDispatcherServlet extends HttpServlet {
private Map<String,Object> mapping = new HashMap<String, Object>();
@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 {
doDispatch(req,resp);
} catch (Exception e) {
resp.getWriter().write("500 Exception " + Arrays.toString(e.getStackTrace()));
}
}
private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
String url = req.getRequestURI();
String contextPath = req.getContextPath();
url = url.replace(contextPath, "").replaceAll("/+", "/");
if(!this.mapping.containsKey(url)){resp.getWriter().write("404 Not Found!!");return;}
Method method = (Method) this.mapping.get(url);
Map<String,String[]> params = req.getParameterMap();
method.invoke(this.mapping.get(method.getDeclaringClass().getName()),new Object[]{req,resp,params.get("name")[0]});
}
//init方法肯定干得的初始化的工作
//inti首先我得初始化所有的相关的类，IOC容器、servletBean
@Override
public void init(ServletConfig config) throws ServletException {
InputStream is = null;
try{
Properties configContext = new Properties();
is = this.getClass().getClassLoader().getResourceAsStream(config.getInitParameter("contextConfigLocation"));
configContext.load(is);
String scanPackage = configContext.getProperty("scanPackage");
doScanner(scanPackage);
for (String className : mapping.keySet()) {
if(!className.contains(".")){continue;}
Class<?> clazz = Class.forName(className);
if(clazz.isAnnotationPresent(GPController.class)){
mapping.put(className,clazz.newInstance());
String baseUrl = "";
if (clazz.isAnnotationPresent(GPRequestMapping.class)) {
GPRequestMapping requestMapping = clazz.getAnnotation(GPRequestMapping.class);
baseUrl = requestMapping.value();
}
Method[] methods = clazz.getMethods();
for (Method method : methods) {
if (!method.isAnnotationPresent(GPRequestMapping.class)) { continue; }
GPRequestMapping requestMapping = method.getAnnotation(GPRequestMapping.class);
String url = (baseUrl + "/" + requestMapping.value()).replaceAll("/+", "/");
mapping.put(url, method);
System.out.println("Mapped " + url + "," + method);
}
}else if(clazz.isAnnotationPresent(GPService.class)){
GPService service = clazz.getAnnotation(GPService.class);
String beanName = service.value();
if("".equals(beanName)){beanName = clazz.getName();}
Object instance = clazz.newInstance();
mapping.put(beanName,instance);
for (Class<?> i : clazz.getInterfaces()) {
mapping.put(i.getName(),instance);
}
}else {continue;}
}
for (Object object : mapping.values()) {
if(object == null){continue;}
Class clazz = object.getClass();
if(clazz.isAnnotationPresent(GPController.class)){
Field [] fields = clazz.getDeclaredFields();
for (Field field : fields) {
if(!field.isAnnotationPresent(GPAutowired.class)){continue; }
GPAutowired autowired = field.getAnnotation(GPAutowired.class);
String beanName = autowired.value();
if("".equals(beanName)){beanName = field.getType().getName();}
field.setAccessible(true);
try {
field.set(mapping.get(clazz.getName()),mapping.get(beanName));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
}
} catch (Exception e) {
}finally {
if(is != null){
try {is.close();} catch (IOException e) {
e.printStackTrace();
}
}
}
System.out.print("GP MVC Framework is init");
}
private void doScanner(String scanPackage) {
URL url = this.getClass().getClassLoader().getResource("/" + scanPackage.replaceAll("\\.","/"));
File classDir = new File(url.getFile());
for (File file : classDir.listFiles()) {
if(file.isDirectory()){ doScanner(scanPackage + "." + file.getName());}else {
if(!file.getName().endsWith(".class")){continue;}
String clazzName = (scanPackage + "." + file.getName().replace(".class",""));
mapping.put(clazzName,null);
}
}
}
}
1.7.实现V2版本
在 V1版本上进了优化，采用了常用的设计模式（工厂模式、单例模式、委派模式、策略模式），将 inito方法中的代 码进行封装。按照之前的实现思路，先搭基础框架,再填肉注血,具体代码如下:
//初始化阶段
@Override
public void init(ServletConfig config) throws ServletException {
//1、加载配置文件
doLoadConfig(config.getInitParameter("contextConfigLocation"));
//2、扫描相关的类
doScanner(contextConfig.getProperty("scanPackage"));
//3、初始化扫描到的类，并且将它们放入到ICO容器之中
doInstance();
//4、完成依赖注入
doAutowired();
//5、初始化HandlerMapping
initHandlerMapping();
System.out.println("GP Spring framework is init.");
}
声明全局的成员变量，其中IOC容器就是注册时单例的具体案例：
//保存application.properties配置文件中的内容 private Properties contextConfig = new Properties(); //保存扫描的所有的类名 private List<String> classNames = new ArrayList<String>(); //传说中的IOC容器，我们来揭开它的神秘面纱 //为了简化程序，暂时不考虑ConcurrentHashMap // 主要还是关注设计思想和原理 private Map<String,Object> ioc = new HashMap<String,Object>(); //保存url和Method的对应关系 private Map<String,Method> handlerMapping = new HashMap<String,Method>();
实现 doLoadConfig方法:
//加载配置文件
private void doLoadConfig(String contextConfigLocation) {
//直接从类路径下找到Spring主配置文件所在的路径
//并且将其读取出来放到Properties对象中
//相对于scanPackage=com.gupaoedu.demo 从文件中保存到了内存中
InputStream fis = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);
try {
contextConfig.load(fis);
} catch (IOException e) {
e.printStackTrace();
}finally {
if(null != fis){
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
实现doScanner()方 法 ：
//扫描出相关的类
private void doScanner(String scanPackage) {
//scanPackage = com.gupaoedu.demo ，存储的是包路径
//转换为文件路径，实际上就是把.替换为/就OK了
//classpath
URL url = this.getClass().getClassLoader().getResource("/" + scanPackage.replaceAll("\\.","/"));
File classPath = new File(url.getFile());
for (File file : classPath.listFiles()) {
if(file.isDirectory()){
doScanner(scanPackage + "." + file.getName());
}else{
if(!file.getName().endsWith(".class")){ continue;}
String className = (scanPackage + "." + file.getName().replace(".class",""));
classNames.add(className);
}
}
}
实现dolnstance()方法，dolnstance。方法就是工厂模式的具体实现：
private void doInstance() {
//初始化，为DI做准备
if(classNames.isEmpty()){return;}
try {
for (String className : classNames) {
Class<?> clazz = Class.forName(className);
//什么样的类才需要初始化呢？
//加了注解的类，才初始化，怎么判断？
//为了简化代码逻辑，主要体会设计思想，只举例 @Controller和@Service,
// @Componment...就一一举例了
if(clazz.isAnnotationPresent(GPController.class)){
Object instance = clazz.newInstance();
//Spring默认类名首字母小写
String beanName = toLowerFirstCase(clazz.getSimpleName());
ioc.put(beanName,instance);
}else if(clazz.isAnnotationPresent(GPService.class)){
//1、自定义的beanName
GPService service = clazz.getAnnotation(GPService.class);
String beanName = service.value();
//2、默认类名首字母小写
if("".equals(beanName.trim())){
beanName = toLowerFirstCase(clazz.getSimpleName());
}
Object instance = clazz.newInstance();
ioc.put(beanName,instance);
//3、根据类型自动赋值,投机取巧的方式
for (Class<?> i : clazz.getInterfaces()) {
if(ioc.containsKey(i.getName())){
throw new Exception("The “" + i.getName() + "” is exists!!");
}
//把接口的类型直接当成key了
ioc.put(i.getName(),instance);
}
}else {
continue;
}
}
}catch (Exception e){
e.printStackTrace();
}
}
为了处理方便,自己实现了 toLowerFirstCase方法,来实现类名首字母小写,具体代码如下：
//如果类名本身是小写字母，确实会出问题
//但是我要说明的是：这个方法是我自己用，private的
//传值也是自己传，类也都遵循了驼峰命名法
//默认传入的值，存在首字母小写的情况，也不可能出现非字母的情况
//为了简化程序逻辑，就不做其他判断了，大家了解就OK
//其实用写注释的时间都能够把逻辑写完了
private String toLowerFirstCase(String simpleName) {
char [] chars = simpleName.toCharArray();
//之所以加，是因为大小写字母的ASCII码相差32，
// 而且大写字母的ASCII码要小于小写字母的ASCII码
//在Java中，对char做算学运算，实际上就是对ASCII码做算学运算
chars[0] += 32;
return String.valueOf(chars);
}
实现 doAutowired方法：
//自动依赖注入
private void doAutowired() {
if(ioc.isEmpty()){return;}
for (Map.Entry<String, Object> entry : ioc.entrySet()) {
//Declared 所有的，特定的 字段，包括private/protected/default
//正常来说，普通的OOP编程只能拿到public的属性
Field[] fields = entry.getValue().getClass().getDeclaredFields();
for (Field field : fields) {
if(!field.isAnnotationPresent(GPAutowired.class)){continue;}
GPAutowired autowired = field.getAnnotation(GPAutowired.class);
//如果用户没有自定义beanName，默认就根据类型注入
//这个地方省去了对类名首字母小写的情况的判断，这个作为课后作业
//小伙伴们自己去完善
String beanName = autowired.value().trim();
if("".equals(beanName)){
//获得接口的类型，作为key待会拿这个key到ioc容器中去取值
beanName = field.getType().getName();
}
//如果是public以外的修饰符，只要加了@Autowired注解，都要强制赋值
//反射中叫做暴力访问， 强吻
field.setAccessible(true);
try {
//用反射机制，动态给字段赋值
field.set(entry.getValue(),ioc.get(beanName));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
}
实现dolnitHandlerMapping方法，handlerMapping就是策略模式的应用案例：
//初始化url和Method的一对一对应关系
private void initHandlerMapping() {
if(ioc.isEmpty()){ return; }
for (Map.Entry<String, Object> entry : ioc.entrySet()) {
Class<?> clazz = entry.getValue().getClass();
if(!clazz.isAnnotationPresent(GPController.class)){continue;}
//保存写在类上面的@GPRequestMapping("/demo")
String baseUrl = "";
if(clazz.isAnnotationPresent(GPRequestMapping.class)){
GPRequestMapping requestMapping = clazz.getAnnotation(GPRequestMapping.class);
baseUrl = requestMapping.value();
}
//默认获取所有的public方法
for (Method method : clazz.getMethods()) {
if(!method.isAnnotationPresent(GPRequestMapping.class)){continue;}
GPRequestMapping requestMapping = method.getAnnotation(GPRequestMapping.class);
//优化
// //demo///query
String url = ("/" + baseUrl + "/" + requestMapping.value())
.replaceAll("/+","/");
handlerMapping.put(url,method);
System.out.println("Mapped :" + url + "," + method);
}
}
}
到这里位置初始化阶段就已经完成，接下实现运行阶段的逻辑，来看doPost/doGet的代码:
@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、调用，运行阶段
try {
doDispatch(req,resp);
} catch (Exception e) {
e.printStackTrace();
resp.getWriter().write("500 Exection,Detail : " + Arrays.toString(e.getStackTrace()));
}
}
doPost()方法中，用了委派模式，委派模式的具体逻辑在doDispatch方法中：
private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
String url = req.getRequestURI();
String contextPath = req.getContextPath();
url = url.replace(contextPath, "").replaceAll("/+", "/");
if(!this.mapping.containsKey(url)){resp.getWriter().write("404 Not Found!!");return;}
Method method = (Method) this.mapping.get(url);
Map<String,String[]> params = req.getParameterMap();
method.invoke(this.mapping.get(method.getDeclaringClass().getName()),new Object[]{req,resp,params.get("name")[0]});
}
在以上代码中，doDispatch。虽然完成了动态委派并反射调用，但对url参数处理还是静态代码。
的动态获E
要实现url参数
,其实还稍微有些复杂。我们可以优化doDispatch方法的实现逻辑，代码如下:
private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
//绝对路径
String url = req.getRequestURI();
//处理成相对路径
String contextPath = req.getContextPath();
url = url.replaceAll(contextPath,"").replaceAll("/+","/");
if(!this.handlerMapping.containsKey(url)){
resp.getWriter().write("404 Not Found!!!");
return;
}
Method method = this.handlerMapping.get(url);
//从reqest中拿到url传过来的参数
Map<String,String[]> params = req.getParameterMap();
//获取方法的形参列表
Class<?> [] parameterTypes = method.getParameterTypes();
Object [] paramValues = new Object[parameterTypes.length];
for (int i = 0; i < parameterTypes.length; i ++) {
Class parameterType = parameterTypes[i];
//不能用instanceof，parameterType它不是实参，而是形参
if(parameterType == HttpServletRequest.class){
paramValues[i] = req;
continue;
}else if(parameterType == HttpServletResponse.class){
paramValues[i] = resp;
continue;
}else if(parameterType == String.class){
GPRequestParam requestParam = (GPRequestParam)parameterType.getAnnotation(GPRequestParam.class);
if(params.containsKey(requestParam.value())) {
for (Map.Entry<String,String[]> param : params.entrySet()){
String value = Arrays.toString(param.getValue())
.replaceAll("\\[|\\]","")
.replaceAll("\\s",",");
paramValues[i] = value;
}
}
}
}
//投机取巧的方式
//通过反射拿到method所在class，拿到class之后还是拿到class的名称
//再调用toLowerFirstCase获得beanName
String beanName = toLowerFirstCase(method.getDeclaringClass().getSimpleName());
method.invoke(ioc.get(beanName),paramValues);
}
1.8.实现V3版本
在 V2版本中，基本功能以及完全实现，但代码的优雅程度还不如人意。譬如HandlerMapping还不能像SpringMVC 一样支持正则,url参数还不支持强制类型转换,在反射调用前还需要重新获取beanName ,在V3版本中,下面我们
继续优化。
首先，改造HandlerMapping , 在真实的Spring源码中，HandlerMapping其实是一个List而非Mapo List中的元
素是一个自定义的类型。现在我们来仿真写一段代码，先定义一个内部类Handler类 :
//保存一个url和一个Method的关系
private class Handler {
//必须把url放到HandlerMapping才好理解吧
private Pattern pattern; //正则
private Method method;
private Object controller;
private Class<?> [] paramTypes;
public Pattern getPattern() {
return pattern;
}
public Method getMethod() {
return method;
}
public Object getController() {
return controller;
}
public Class<?>[] getParamTypes() {
return paramTypes;
}
//形参列表
//参数的名字作为key,参数的顺序，位置作为值
private Map<String,Integer> paramIndexMapping;
public Handler(Pattern pattern, Object controller, Method method) {
this.pattern = pattern;
this.method = method;
this.controller = controller;
paramTypes = method.getParameterTypes();
paramIndexMapping = new HashMap<String, Integer>();
putParamIndexMapping(method);
}
private void putParamIndexMapping(Method method){
//提取方法中加了注解的参数
//把方法上的注解拿到，得到的是一个二维数组
//因为一个参数可以有多个注解，而一个方法又有多个参数
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);
}
}
}
}
//提取方法中的request和response参数
Class<?> [] paramsTypes = method.getParameterTypes();
for (int i = 0; i < paramsTypes.length ; i ++) {
Class<?> type = paramsTypes[i];
if(type == HttpServletRequest.class ||
type == HttpServletResponse.class){
paramIndexMapping.put(type.getName(),i);
}
}
}
}
然后，优化HandlerMapping的结构，代码如下：
//保存所有的URL和方法的映射关系 private List<Handler> handlerMapping = new ArrayList<Handler>();
修改 dolnitHandlerMapping方 法 ：
//初始化url和Method的一对一对应关系
private void initHandlerMapping() {
if(ioc.isEmpty()){ return; }
for (Map.Entry<String, Object> entry : ioc.entrySet()) {
Class<?> clazz = entry.getValue().getClass();
if(!clazz.isAnnotationPresent(GPController.class)){continue;}
//保存写在类上面的@GPRequestMapping("/demo")
String baseUrl = "";
if(clazz.isAnnotationPresent(GPRequestMapping.class)){
GPRequestMapping requestMapping = clazz.getAnnotation(GPRequestMapping.class);
baseUrl = requestMapping.value();
}
//默认获取所有的public方法
for (Method method : clazz.getMethods()) {
if(!method.isAnnotationPresent(GPRequestMapping.class)){continue;}
GPRequestMapping requestMapping = method.getAnnotation(GPRequestMapping.class);
//优化
// //demo///query
String regex = ("/" + baseUrl + "/" + requestMapping.value())
.replaceAll("/+","/");
Pattern pattern = Pattern.compile(regex);
this.handlerMapping.add(new Handler(pattern,entry.getValue(),method));
System.out.println("Mapped :" + pattern + "," + method);
}
}
}
修改 doDispatch()方法:
private void doDispatch(HttpServletRequest req, HttpServletResponse resp) throws Exception {
Handler handler = getHandler(req);
if (handler == null) {
resp.getWriter().write("404 Not Found!!!");
return;
}
//获得方法的形参列表
Class<?>[] paramTypes = handler.getParamTypes();
Object[] paramValues = new Object[paramTypes.length];
Map<String, String[]> params = req.getParameterMap();
for (Map.Entry<String, String[]> parm : params.entrySet()) {
String value = Arrays.toString(parm.getValue()).replaceAll("\\[|\\]", "")
.replaceAll("\\s", ",");
if (!handler.paramIndexMapping.containsKey(parm.getKey())) {
continue;
}
int index = handler.paramIndexMapping.get(parm.getKey());
paramValues[index] = convert(paramTypes[index], value);
}
if (handler.paramIndexMapping.containsKey(HttpServletRequest.class.getName())) {
int reqIndex = handler.paramIndexMapping.get(HttpServletRequest.class.getName());
paramValues[reqIndex] = req;
}
if (handler.paramIndexMapping.containsKey(HttpServletResponse.class.getName())) {
int respIndex = handler.paramIndexMapping.get(HttpServletResponse.class.getName());
paramValues[respIndex] = resp;
}
Object returnValue = handler.method.invoke(handler.controller, paramValues);
if (returnValue == null || returnValue instanceof Void) {
return;
}
resp.getWriter().write(returnValue.toString());
}
private Handler getHandler(HttpServletRequest req) {
if (handlerMapping.isEmpty()) {
return null;
}
//绝对路径
String url = req.getRequestURI();
//处理成相对路径
String contextPath = req.getContextPath();
url = url.replaceAll(contextPath, "").replaceAll("/+", "/");
for (Handler handler : this.handlerMapping) {
Matcher matcher = handler.getPattern().matcher(url);
if (!matcher.matches()) {
continue;
}
return handler;
}
return null;
}
//url传过来的参数都是String类型的，HTTP是基于字符串协议
//只需要把String转换为任意类型就好
private Object convert(Class<?> type, String value) {
//如果是int
if (Integer.class == type) {
return Integer.valueOf(value);
} else if (Double.class == type) {
return Double.valueOf(value);
}
//如果还有double或者其他类型，继续加if
//这时候，我们应该想到策略模式了
//在这里暂时不实现，希望小伙伴自己来实现
return value;
}
在以上代码中,增加了两个方法，一个是getHandler。方法,主要负责处理url的正则匹配;一个是 convert()方 法 ，主要负责url参数的强制类型转换。
至此,手写Mini版 SpringMVC框架就已全部完成。
1.9.运行效果演示
在浏览器输入：http://localhost:8080/demo/query.json?name=Tom , 就会得到下面的结果：
当然，真正的Spring要复杂很多，本课中主要通过手写的形式，了解Spring的基本设计思路以及设计 模式如何应用，在以后的学习中，我们还会继续手写更加高仿真版本的Spring2.0。