Spring手写简化版MVC流程详解

spring是一个非常流行的技术框架，其中spring mvc组件在其中非常重要的地位，主要面要客户端提供服务，我们今天来手写一个简化版的mvc，且包括ioc部分，主要利用servlet机制来实现，类的关系如下：

准备注解类，类于spring的@Autowired、@Service、@Controller、@RequestMapping、@RequestParam

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CSAutowired {
    String value() default "";
}
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CSController {
    String value() default "";
}
@Target({ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CSRequestMapping {
    String value() default "";
}
@Target({ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CSRequestParam {
    String value() default "";
}
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CSService {
    String value() default "";
}

准备service interface

public interface IDemoService {
    public String get(String name);
}

准备service实现类，利用@CSService

@CSService
public class DemoService implements IDemoService {
    @Override
    public String get(String name) {
        return "My name is "+name;
    }
}

准备对外服务的类，主要利用@CSController注解

@CSController
@CSRequestMapping("/demo")
public class DemoAction {
    @CSAutowired
    private IDemoService demoService;
    @CSRequestMapping("/query")
    public void query(HttpServletRequest req, HttpServletResponse resp, @CSRequestParam("name") String name){
        String result=demoService.get(name);
        try {
            resp.getWriter().write(result);
        } catch (IOException exception) {
            exception.printStackTrace();
        }
    }
    @CSRequestMapping("/add")
    public void add(HttpServletRequest req, HttpServletResponse resp, @CSRequestParam("aa") Integer a,@CSRequestParam("b") Integer b){
        try {
            resp.getWriter().write(a+"+"+b+"="+(a+b));
        } catch (IOException exception) {
            exception.printStackTrace();
        }
    }
    @CSRequestMapping("/remove")
    public void remove(HttpServletRequest req, HttpServletResponse resp, @CSRequestParam("id") Integer id){
        try {
            resp.getWriter().write("id="+id);
        } catch (IOException exception) {
            exception.printStackTrace();
        }
    }
}

准备servlet

主要实现了以下功能：

1).根据@CSController对外服务的url如何mapping到具体方法 doHandlerMap

2).service和controller bean的管理 iocBeans

3).如何实列化bean doInstance

4).如何获取url中参数值 doDispatch中

5).找到需要加载的class doScanner

6).如何自动autowired doAutoWried

public class CSDispatchServlet extends HttpServlet {
    public static String urlPattern="/custom";
    private void doDispatch(HttpServletRequest request,HttpServletResponse response) throws Exception{
        String url=request.getRequestURI();
        String contextPath=request.getContextPath();
        url=url.replace(urlPattern,"");
        if(!handlerMap.containsKey(url)){
            response.getWriter().write("404 not found!");
            return;
        }
        Method method=handlerMap.get(url);
        Annotation[][] methodParameterAnnotations= method.getParameterAnnotations();
        Parameter[]  methodParameters= method.getParameters();
        Annotation[][] paramerterAnnotations=method.getParameterAnnotations();
        ArrayList