被继承的抽象类 BaseServlet.java
package cn.day1901.servlet;
import java.io.IOException;
import java.lang.reflect.Method;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public abstract class BaseServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/*
* 客户端必须传method方法
* 获取参数，用来识别处理方法,判断是哪一个方法，是哪一个就调用哪一个
* 得到方法名，通过反射来调用方法, 得到当前类的Class对象,然后调用安的方法进行查询，得到Method
* 我们要得到当前类的方法，所以需要得到当前类的Class
* getDeclaredMethod 可以获取任意方法 像，protected修饰的
* getMethod 只可以获取 修饰符为 public 的方法
*/
String methodName = request.getParameter("method");
if(methodName == null || methodName.trim().isEmpty()) {
throw new RuntimeException("您没有传递method参数，无法确定您想要调用的方法！");
}
Method me =null;
try {
me = this.getClass().getDeclaredMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
} catch (Exception e) {
throw new RuntimeException(e+"你要调用的方法："+methodName+"不存在");
}
Object req = null;
Object resp = null;
try {
String result = (String) me.invoke(this, request,response);
/*
* 获取请求处理方法执行返回的字符串，它表示转发或重定向的路径，帮它完成转发或重定向
* 查看返回的字符串是否包含冒号，如果没有，就表示转发，如果有使用冒号分割字符串，得到前缀和后前缀，如果是f则转，r重定向
*/
System.out.println(">"+result);
if(result == null || result.trim().isEmpty()) {return;}
if(result.contains(":")) {
int index=result.indexOf(":");//获取冒号的位置
String s = result.substring(0, 1);//截取前缀
String path = result.substring(index+1);//截取后缀
if(s.equalsIgnoreCase("r")) {
response.sendRedirect(request.getContextPath()+path);
}else if(s.equalsIgnoreCase("f")) {
request.getRequestDispatcher(path).forward(request, response);
}else {
throw new RuntimeException("你的指定操作"+s+",当前版本不支持！");
}
}else {
System.out.println("没有冒号");
request.getRequestDispatcher(result).forward(request, response);
}
} catch (Exception e) {
throw new RuntimeException(e+"你调用方法内部"+methodName+"冒出的异常");
}
}
}
继承它，使用安！
package cn.day1901.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class Bservlet extends BaseServlet {
private static final long serialVersionUID = 1L;
public String defaultForword(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("addUser");
return "/index.jsp";
}
public String addUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("addUser");
return "f:/index.jsp";
}
public String editUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("editUser");
return "r:/index.jsp";
}
public String deleteUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("deleteUser");
return "f:/index.jsp";
}
public String findAllUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("findAllUser");
return "r:/index.jsp";
}
public String nullAllUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("nullAllUser");
return null;
}}
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