spring mvc框架源码分析(三)-执行请求路径所对应方法并返回

之前第一节我们讲了DispatchServlet中会对请求做一些处理,这些处理即是执行请求路径所对应的方法。


获取此请求路径所对应的方法:

    通过这两个方法获取了请求路径以及请求方式

 String url = servletRequest.getRequestURI();
 String method = servletRequest.getMethod();

    然后获取之前在AnnotionUtil方法中获取到的所有的路径和方法,并且找到当前请求路径所对应的字符串集

 List<String> list = (List<String>) getServletContext().getAttribute("annotationList"); String urlAndMethod = url + " " + method; String thisRequest = ""; for (String s : list) { if (s.contains(urlAndMethod)) { thisRequest = s; break; } }

    获取到请求所对应的字符串集后,之后我们需要做的事情就是执行此路径所对应的方法。首先需要判断此路径是否对应有方法,没有的话返回错误页面,之后在路径所对应的字符串集中取出其类名和方法名,并且获取到方法中的参数的类型,最后执行路径所对应方法

  if (!thisRequest.equals("")) {
            String[] stringArray = thisRequest.split(" ");
            try {
                Class<?> cla = Class.forName(stringArray[3]);
                Method[] methods = cla.getMethods();
                Class<?>[] classes = null;
                for (Method method1 : methods) {
                    if (method1.getName().equals(stringArray[4])) { //获取参数类型
                        Class<?>[] parameterTypes = method1.getParameterTypes();
                        for (int i = 0; i < parameterTypes.length; i++) {
                            classes = parameterTypes;
                        }

                    }
                }
                Object o = cla.newInstance(); //实例化当前类
                Object[] objects = getParam(classes);赋予参数值
                String result = (String) cla.getMethod(stringArray[4], classes).invoke(o,objects);//反射执行方法并接受返回结果
                if (stringArray[2].equals(SystemConfig.ResponsePage)) {//处理返回结果
                    servletRequest.getRequestDispatcher("/" + result).forward(servletRequest, servletResponse);
                } else {
                    servletResponse.getWriter().write(result);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }else {
            servletResponse.getWriter().write("error");
        }
    public Object[] getParam(Class<?>[] classes) {
        Object[] objects = null;
        if (classes!=null){
            objects= new Object[classes.length];
//因为目前参数只支持httpServletRequest和httpServletResponse,后续会完善
        for (int i = 0;i<classes.length;i++){
            if (classes[i].getName().contains("HttpServletRequest")){
                objects[i] = httpServletRequest;
            }else if (classes[i].getName().contains("HttpServletRequest")) {
                objects[i] = httpServletResponse;
            }else {
                objects[i] = null;
            }

        }
        }
        return objects;
    }


DispatchServlet:

public class DispatcherServlet extends GenericServlet implements Serializable{

    private HttpServletRequest httpServletRequest = null;
    private HttpServletResponse httpServletResponse = null;

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        HttpServletRequest request;
        HttpServletResponse response;
        try {
            request = (HttpServletRequest)servletRequest;
            response = (HttpServletResponse)servletResponse;
            httpServletRequest = request;
            httpServletResponse = response;
        }catch (Exception e){
            throw new ServletException("non-HTTP request or response");
        }
        this.service(request,response);
    }


    public void service(HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws ServletException, IOException {
        String url = servletRequest.getRequestURI();
        String method = servletRequest.getMethod();
        List<String> list = (List<String>) getServletContext().getAttribute("annotationList");
        String urlAndMethod = url + " " + method;
        String thisRequest = "";

        for (String s : list) {
            if (s.contains(urlAndMethod)) {
                thisRequest = s;
                break;
            }
        }
        if (!thisRequest.equals("")) {
            String[] stringArray = thisRequest.split(" ");
            try {
                Class<?> cla = Class.forName(stringArray[3]);
                Method[] methods = cla.getMethods();
                Class<?>[] classes = null;
                for (Method method1 : methods) {
                    if (method1.getName().equals(stringArray[4])) {
                        Class<?>[] parameterTypes = method1.getParameterTypes();
                        for (int i = 0; i < parameterTypes.length; i++) {
                            classes = parameterTypes;
                        }

                    }
                }
                Object o = cla.newInstance();
                Object[] objects = getParam(classes);
                String result = (String) cla.getMethod(stringArray[4], classes).invoke(o,objects);
                if (stringArray[2].equals(SystemConfig.ResponsePage)) {
                    servletRequest.getRequestDispatcher("/" + result).forward(servletRequest, servletResponse);
                } else {
                    servletResponse.getWriter().write(result);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }else {
            servletResponse.getWriter().write("error");
        }
    }

    public Object[] getParam(Class<?>[] classes) {
        Object[] objects = null;
        if (classes!=null){


            objects= new Object[classes.length];

        for (int i = 0;i<classes.length;i++){
            if (classes[i].getName().contains("HttpServletRequest")){
                objects[i] = httpServletRequest;
            }else if (classes[i].getName().contains("HttpServletRequest")) {
                objects[i] = httpServletResponse;
            }else {
                objects[i] = null;
            }

        }
        }
        return objects;
    }
}


测试:

  @MyRequestMapping(path = "/zhu/html_test",method = RequestMethod.GET)
    public String testOneaa(){
        return "xxx.html";
    }

《spring mvc框架源码分析(三)-执行请求路径所对应方法并返回》

 

  @MyResponseString
    @MyRequestMapping(path = "/zhu/test1",method = RequestMethod.GET)
    public String testA(HttpServletRequest httpServletRequest){
        return "xx";
    }

《spring mvc框架源码分析(三)-执行请求路径所对应方法并返回》

    @MyRequestMapping(path = "/zhu/test",method = RequestMethod.GET)
    public String testOne(){
        return "index.jsp";
    }

《spring mvc框架源码分析(三)-执行请求路径所对应方法并返回》


总结:

    最初的框架较简便,后期会完善它,讲到这大概就讲完了,很简单,只是实现了一些基本的功能还有很多细节没有处理,完整看看整个架构就运用了java的反射和注解,枚举,以及一些java web编程的基本知识,没有涉及到高深的东西,所以还是很好理解的。

项目源码地址:

http://pan.baidu.com/s/1i5sFPxr

    原文作者:Spring Boot
    原文地址: https://blog.csdn.net/asd1098626303/article/details/60868271
    本文转自网络文章,转载此文章仅为分享知识,如有侵权,请联系博主进行删除。
点赞