反射替代各种else if (servlet)
@WebServlet("/order")
public class OrderServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
//获取提交的参数
String method = request.getParameter("method");
//判断参数,调⽤不同的⽅法
if ("add".equals(method)) {
add(request, response);
} else if ("delete".equals(method)) {
delete(request, response);
} else if ("update".equals(method)) {
update(request, response);
} else if ("findAll".equals(method)) {
findAll(request, response);
} else if ("findByPage".equals(method)) {
findByPage(request, response);
}
}
//添加订单功能
public void add(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//删除订单功能(指订单的状态发⽣改变,数据库中并未删除)
public void delete(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//更新订单功能
public void update(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//查找所有订单功能
public void findAll(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//分⻚查找的订单功能
public void findByPage(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
protected void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
doGet(request, response);
}
}
反射技术减少重复性代码（用了反射，性能可能会降低 ）
@WebServlet("/order")
public class OrderServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
try {
//获取提交的参数
String md = request.getParameter("method");
//反射,调⽤⽅法
Class clazz = this.getClass();
//获取⽅法
Method method = clazz.getMethod(md, HttpServletRequest.class,
HttpServletResponse.class);
//执⾏⽅法
method.invoke(this, request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
//添加订单功能
public void add(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//删除订单功能(指订单的状态发⽣改变,数据库中并未删除)
public void delete(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//更新订单功能
public void update(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//查找所有订单功能
public void findAll(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
//分⻚查找的订单功能
public void findByPage(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
}
protected void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
doGet(request, response);
}
}
把反射的代码提取到base，代码就更简洁了
public abstract class baseServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
try {
//获取提交的参数
String md = request.getParameter("method");
//反射,调⽤⽅法
Class clazz = this.getClass();
//获取⽅法
Method method = clazz.getMethod(md, HttpServletRequest.class,
HttpServletResponse.class);
//执⾏⽅法
method.invoke(this, request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {
doGet(request, response);
}
}
