自己动手设计java web框架（三）-执行请求路径所对应方法并返回

摘要: java web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";
}

@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