spring mvc框架源码分析（三）-执行请求路径所对应方法并返回

来源：互联网发布：centos改为中文编辑：程序博客网时间：2024/06/12 23:35

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";    }

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

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

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

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