/*** 请求访问入口(所有请求都会来到这里进行分发)* @author zhanglr**/
@WebServlet(name = "BaseServlet", urlPatterns = "/")
public final class BaseServlet extends HttpServlet {private static final long serialVersionUID = 1L;@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {super.service(req, resp);
}}
}

/*** 类注解映射，映射使用的类* * @author zhanglr**/
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE })
public @interface RequestType {String url();/*** 请求方式,get或post,大小写不敏感* @return*/String type();
}

/*** 方法注解映射，映射调用的方法* @author zhanglr**/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface RequestMethod {String name() default "";
}

/*** 用户逻辑控制器* @author zhanglr**/
@RequestType(type = "POST", url = "/user")
public class UserController {private UserService userService = new UserService();@RequestMethod(name = "/login.do")public IActionResult login(HttpServletRequest request, HttpServletResponse response) {// 登录逻辑return ErrorCodeResponse.Success.getSuccess("success");}/*** 用户注册* @param request* @param response* @return*/@RequestMethod(name = "/register.do")public IActionResult registerUser(HttpServletRequest request, HttpServletResponse response) {UserRegisterRequest userRegisterRequest = ClassUtil.getObjectFromResquest(request, UserRegisterRequest.class);if (Types.isEmpty(userRegisterRequest.getAccount())) {return ErrorCodeResponse.AccountIsNull.getError();}if (Types.isEmpty(userRegisterRequest.getPassword())) {return ErrorCodeResponse.PasswordIsNull.getError();}if (Types.isEmpty(userRegisterRequest.getAgainPwd())) {return ErrorCodeResponse.ParamIsNull.getError("二次密码");}return userService.registerUser(userRegisterRequest);}
）

/*** 请求访问入口(所有请求都会来到这里进行分发)* @author zhanglr**/
@WebServlet(name = "BaseServlet", urlPatterns = "/")
public final class BaseServlet extends HttpServlet {private static final long serialVersionUID = 1L;@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {super.service(req, resp);req.setCharacterEncoding("utf-8");resp.setContentType("text/html");resp.setCharacterEncoding("utf-8");String contextPath = req.getContextPath();String requestUri = req.getRequestURI();// 去除contextPath为真实请求路径String realUri = requestUri.substring(contextPath.length(), requestUri.length());// 获取入口包下的所有controller类List<Class<?>> classes = ClassUtil.getAllClassByPackageName(this.getClass().getPackage());for (Class<?> currClass : classes) {// 获取当前类的注解RequestType requestType = currClass.getAnnotation(RequestType.class);String methodType = req.getMethod().toLowerCase().trim();// 当前类注解不为空，请求路径以该注解url开头且请求类型为注解type则获取该类if (requestType != null && requestType.type().toLowerCase().trim().equals(methodType)&& realUri.contains(requestType.url()) && realUri.startsWith(requestType.url())) {// 获取当前类的所有方法Method[] methods = currClass.getDeclaredMethods();for (Method currMethod : methods) {// 获取当前方法的注解RequestMethod requestMethod = currMethod.getAnnotation(RequestMethod.class);// 当前方法注解不为空且请求路径以该注解name结尾，则获取该方法if (requestMethod != null && realUri.contains(requestMethod.name()) && realUri.endsWith(requestMethod.name())) {try {IActionResult result = (IActionResult) currMethod.invoke(currClass.newInstance(), req, resp);if (result != null && result.getData() != null) {resp.getWriter().print(result.getData());resp.getWriter().flush();}} catch (Exception e) {e.printStackTrace();}break;}}break;}}}
}

public interface IActionResult {String getData();
}

public enum ErrorCodeResponse implements IActionResult {Success(0), Error(1),// 公共错误 10000+ParamIsNull(10001, " %s 不能为空  "), AccountIsNull(10002, "用户账号不能为空"), PasswordIsNull(10003, "用户密码不能为空");private int code;private String msg;private ErrorCodeResponse(int code) {this.code = code;}private ErrorCodeResponse(int code, String msg) {this.code = code;this.msg = msg;}public IActionResult getError() {return this;}public IActionResult getError(String param) {this.msg = String.format(this.msg, param);return this;}public IActionResult getError(int code, String param) {this.code = code;this.msg = param;return this;}public IActionResult getSuccess(String param) {this.msg = param;return this;}// 拓展参数valueprivate Object data = null;public ErrorCodeResponse setExtraData(Object data) {this.data = data;return this;}@Overridepublic String getData() {Gson gson = new Gson();Map<String, Object> params = new HashMap<String, Object>();params.put("code", this.code);params.put("msg", this.msg);if (Types.isNotEmpty(data)) {if (data instanceof String) {params.put("data", data);} else {params.put("data", gson.toJson(data));}} else {params.put("data", "");}return gson.toJson(params);}}

public final class ClassUtil {
/*** 将request请求数据转换为实体* @param request* @param clazz* @return*/public static <T> T getObjectFromResquest(HttpServletRequest request, Class<T> clazz) {try {T t = clazz.newInstance();Map<String, Method> methods = new HashMap<>();for (Method method : clazz.getMethods()) {methods.put(method.getName(), method);}Enumeration<String> keys = request.getParameterNames();while (keys.hasMoreElements()) {String key = (String) keys.nextElement();String value = request.getParameter(key);if (value.isEmpty())continue;String fieldName = key.substring(0, 1).toUpperCase() + key.substring(1);Method setMethod = methods.get("set" + fieldName);if (setMethod == null)continue;invokeSetMethod(t, setMethod, value);}return t;} catch (InstantiationException | IllegalAccessException | SecurityException | IllegalArgumentException| InvocationTargetException e) {e.printStackTrace();}return null;}private static void invokeSetMethod(Object obj, Method method, Object value)throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {Class<?>[] types = method.getParameterTypes();if (types != null && types.length == 1) {Class<?> typeClass = types[0];if (value.getClass() == typeClass) {method.invoke(obj, value);return;}if (typeClass == String.class)method.invoke(obj, String.valueOf(value));else if (typeClass == Integer.class || typeClass == int.class) {method.invoke(obj, Integer.valueOf(String.valueOf(value)));} else if (typeClass == Long.class || typeClass == long.class) {method.invoke(obj, Long.valueOf(String.valueOf(value)));}}}
}