在Servlet中封装转发(服务器端跳转)和重定向（客户端跳转）

你的名字 2023-07-04 12:35 86阅读 0赞

1 基础的Servlet类

package com.servlet;
    
    import javax.servlet.ServletException;
    
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.lang.reflect.Method;
    
    
    public abstract class BaseServlet extends HttpServlet { 
        @Override
        public void service(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException { 
            System.out.println("******");
            String mehtodName=req.getParameter("method");
            if(mehtodName==null||mehtodName.trim().isEmpty()){ 
                throw new RuntimeException("没有获得到method参数");
            }
            Class c=this.getClass();
            Method method=null;
            try { 
                method= c.getMethod(mehtodName, HttpServletRequest.class, HttpServletResponse.class);
    
            } catch (NoSuchMethodException e) { 
                throw new RuntimeException("调用的方法不存在-->"+mehtodName);
            }
    
            try { 
                //method.invoke(this,req,resp);
                String result=(String) method.invoke(this,req,resp);
                if(result==null|| result.trim().isEmpty()){ 
                    return;
                }
                //f 表示转发
                //r 表示中重定向
                if(result.contains(":")){ 
                        //使用冒号分割字符串
                    int index=result.indexOf(":");//获取冒号的位置
                    String s=result.substring(0,index); //截取前缀,表示操作
                    String path=result.substring(index+1);//截取后缀，表示路径
                    if(s.equalsIgnoreCase("r")){ //如果前缀是r，那么重定向！
                        resp.sendRedirect(req.getContextPath()+path);
                    }else if(s.equalsIgnoreCase("f")){ 
                        req.getRequestDispatcher(path).forward(req,resp);
                    }else { 
                        throw new RuntimeException("你指定的操作："+s+",当前版本无法完成。");
                    }
                }else { //没有冒号，默认为转发
                    req.getRequestDispatcher(result).forward(req,resp);
                }
    
            } catch (Exception e) { 
                throw new RuntimeException("调用的方法-->"+mehtodName+"，在内部发生了异常。。。"+e.getMessage());
            }
        }
    }

2 继承类

package com.servlet;
    
    import javax.servlet.ServletException;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    
    
    public class AServlet extends BaseServlet { 
    
    
        public String addUser(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { 
            System.out.println("addUser()....");
            return "f:/index.jsp"; //跳转
        }
        public String editUser(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { 
            System.out.println("editUser()....");
            return "r:/index.jsp";//重定向
        }
        public String deleteUser(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { 
            System.out.println("deleteUser()....");
            return null;
    
        }
    }

以后我们可以这样封装经常重复代码  
sendRedirect  
getRequestDispatcher  
操作了。