重定向不过去,Java语言交流,技术交流,鱼C论坛

她与晚风 发表于 2023-4-29 11:25:50

重定向不过去

单独拿出来重定向没有问题

她与晚风 发表于 2023-4-29 11:28:06

单独拿出来可以跳转

陶远航 发表于 2023-4-29 17:31:05

你问问ChatGPT

歌者文明清理员 发表于 2023-4-29 17:49:26

wheres your code?

她与晚风 发表于 2023-4-29 18:55:41

本帖最后由她与晚风于 2023-4-29 19:00 编辑

歌者文明清理员发表于 2023-4-29 17:49
wheres your code?

package bj;

import MyUtil.DepartmentUser;
import MyUtil.EmoloyeeUser;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;

@WebServlet({"/dept/List","/dept/Delete","/dept/Detail","/dept/Update","/dept/login"})
public class ServletList extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

   Connection connection = null;
   PreparedStatement preparedStatement = null;
   ResultSet resultSet = null;
   String sql;
   try {
         Class.forName("com.mysql.cj.jdbc.Driver");
         connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/myemployees","root","123456");
         connection.setAutoCommit(false);
         if("/dept/List".equals(request.getServletPath())){
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               System.out.println("------------------------------------");
               //request.getRequestDispatcher("/index.jsp").forward(request,response);
               response.sendRedirect(request.getContextPath() + "/index.jsp");
            }
            ArrayList<DepartmentUser> arrayList = new ArrayList<>();
            sql = "select department_id,department_name,manager_id,city from departments e left join locations l on e.location_id = l.location_id";
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
               String department_id = resultSet.getString("department_id");
               String department_name = resultSet.getString("department_name");
               String manager_id = resultSet.getString("manager_id");
               String city = resultSet.getString("city");
               DepartmentUser departmentUser = new DepartmentUser(department_id,department_name,manager_id,city);
               arrayList.add(departmentUser);
            }
            request.setAttribute("list",arrayList);
            connection.setAutoCommit(true);
            request.getRequestDispatcher("/deptList.jsp").forward(request,response);
         } else if ("/dept/Delete".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath());
            }
            connection.setAutoCommit(false);
            String department_id = request.getParameter("department_id");
            sql = "delete from departments where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            int i = preparedStatement.executeUpdate();

            sql = "delete from employees where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            int j = preparedStatement.executeUpdate();
            connection.setAutoCommit(true);
            if(i !=0 || j != 0){
               System.out.println("操作成功");
            }
            response.sendRedirect(request.getContextPath() + "/dept/List");
         } else if ("/dept/Detail".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               System.out.println("------------------------------------");
               response.sendRedirect(request.getContextPath() + "/index.jsp");
            }
            connection.setAutoCommit(false);
            ArrayList arrayList = new ArrayList();
            String department_id = request.getParameter("department_id");
            sql = "select employee_id,last_name,job_id,manager_id,department_id,hiredate from employees where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
               String employee_id= resultSet.getString("employee_id");
               String last_name = resultSet.getString("last_name");
               String job_id = resultSet.getString("job_id");
               String manager_id = resultSet.getString("manager_id");
               department_id = resultSet.getString("department_id");
               String hiredate = resultSet.getString("hiredate");
               EmoloyeeUser emoloyeeUser = new EmoloyeeUser(employee_id,last_name,job_id,manager_id,department_id,hiredate);
               arrayList.add(emoloyeeUser);
            }
            connection.setAutoCommit(true);
            request.setAttribute("detail",arrayList);
            request.getRequestDispatcher("/deptDetail.jsp").forward(request,response);
         } else if ("/dept/Update".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath());
            }
            connection.setAutoCommit(false);
            String department_id = request.getParameter("department_id");
            System.out.println(department_id);
            String department_name = request.getParameter("department_name");
            String manager_id = request.getParameter("manager_id");
            String city = request.getParameter("city");

            sql = "update departments set department_name = ?,manager_id = ? where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,department_name);
            preparedStatement.setInt(2, Integer.parseInt(manager_id));
            preparedStatement.setInt(3, Integer.parseInt(department_id));
            int j = preparedStatement.executeUpdate();

            sql = "update locations set city = ? where location_id = (select location_id from departments where department_id = ?)";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,city);
            preparedStatement.setInt(2, Integer.parseInt(department_id));
            int i = preparedStatement.executeUpdate();
            if(i != 0 && j != 0){
               System.out.println("修改成功");
            }
            connection.setAutoCommit(true);

            response.sendRedirect(request.getContextPath() + "/dept/List");
         } else if ("/dept/login".equals(request.getServletPath())) {
            HttpSession session = request.getSession();
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            session.setAttribute("username",username);
            sql = "select * from t_login where username = ? and password = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,username);
            preparedStatement.setInt(2, Integer.parseInt(password));
            resultSet = preparedStatement.executeQuery();
            if(resultSet.next()){
               System.out.println("登录成功");
               connection.setAutoCommit(true);
               response.sendRedirect(request.getContextPath() + "/dept/List");
            }else {
               System.out.println("登录失败");
            }
         }
   } catch (ClassNotFoundException e) {
         throw new RuntimeException(e);
   } catch (SQLException e) {
         try {
            connection.rollback();
         } catch (SQLException ex) {
            throw new RuntimeException(ex);
         }
         throw new RuntimeException(e);
   }finally {
         if(resultSet != null){
            try {
               resultSet.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
         if(preparedStatement != null){
            try {
               preparedStatement.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
         if(connection != null){
            try {
               connection.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
   }
}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   doGet(request,response);
}
}

歌者文明清理员 发表于 2023-4-29 18:58:36

她与晚风发表于 2023-4-29 18:55
package bj;

import MyUtil.DepartmentUser;

对于重定向失败的问题，可以尝试检查以下几点：

[*]重定向的目标 URL 是否正确；
[*]代码中是否存在语法错误或者逻辑错误；
[*]确认是否有足够的权限进行重定向操作；
[*]尝试使用 forward 方法进行页面跳转而非 redirect。

另外，在出现 500 内部服务器错误时，建议查看服务器日志或者在代码中添加异常捕捉代码，以获得更详细的错误信息。

她与晚风 发表于 2023-4-29 18:59:49

歌者文明清理员发表于 2023-4-29 18:58
对于重定向失败的问题，可以尝试检查以下几点：

写成转发形式没有问题,我确认自己重定向的那一句代码没问题

歌者文明清理员 发表于 2023-4-29 19:00:56

她与晚风发表于 2023-4-29 18:59
写成转发形式没有问题,我确认自己重定向的那一句代码没问题

既然使用重定向方式无法解决问题，那就考虑使用转发的方式代替。

将以下代码：

java
response.sendRedirect(request.getContextPath() + "/index.jsp");
改为：

java
request.getRequestDispatcher("/index.jsp").forward(request,response);
并删除目前代码中与之对应的注释即可。

如果使用 forward 仍然不能解决问题，那就可能需要进一步检查代码和服务器配置等方面的问题。

她与晚风 发表于 2023-4-29 19:01:56

歌者文明清理员发表于 2023-4-29 19:00
既然使用重定向方式无法解决问题，那就考虑使用转发的方式代替。

将以下代码：

嗯嗯,主要是重定向错的莫名其妙

她与晚风 发表于 2023-4-29 22:14:22

歌者文明清理员发表于 2023-4-29 17:49
wheres your code?

这是一个Java Web应用程序的错误日志，它的根本原因是IllegalStateException，即没有已经开启的响应可以写入。在该日志中，它是由于应用程序的Servlet尝试发送一个转发请求给浏览器时发生的。然而，应用程序已经在此之前发送了一个响应，所以它不能再写入另一个响应。这通常是由于代码逻辑错误或在同一个请求中多次发送响应导致的。

她与晚风 发表于 2023-4-29 22:14:53

歌者文明清理员发表于 2023-4-29 19:00
既然使用重定向方式无法解决问题，那就考虑使用转发的方式代替。

将以下代码：

查到错误了哥,看不懂,可以给我解释一下吗{:9_241:}

她与晚风 发表于 2023-4-29 22:21:41

本帖最后由她与晚风于 2023-4-29 22:22 编辑

歌者文明清理员发表于 2023-4-29 17:49
wheres your code?

package bj;

import MyUtil.DepartmentUser;
import MyUtil.EmoloyeeUser;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;

@WebServlet({"/dept/List","/dept/Delete","/dept/Detail","/dept/Update","/dept/login"})
public class ServletList extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

   Connection connection = null;
   PreparedStatement preparedStatement = null;
   ResultSet resultSet = null;
   String sql;
   try {
         Class.forName("com.mysql.cj.jdbc.Driver");
         connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/myemployees","root","123456");
         if("/dept/List".equals(request.getServletPath())){
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath() + "/index.jsp");
            }else {
            connection.setAutoCommit(false);
            ArrayList<DepartmentUser> arrayList = new ArrayList<>();
            sql = "select department_id,department_name,manager_id,city from departments e left join locations l on e.location_id = l.location_id";
            preparedStatement = connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
               String department_id = resultSet.getString("department_id");
               String department_name = resultSet.getString("department_name");
               String manager_id = resultSet.getString("manager_id");
               String city = resultSet.getString("city");
               DepartmentUser departmentUser = new DepartmentUser(department_id,department_name,manager_id,city);
               arrayList.add(departmentUser);
            }
            request.setAttribute("list",arrayList);
            connection.setAutoCommit(true);
            request.getRequestDispatcher("/deptList.jsp").forward(request,response);
            }
         } else if ("/dept/Delete".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath() + "/index.jsp");
            }
            connection.setAutoCommit(false);
            String department_id = request.getParameter("department_id");
            sql = "delete from departments where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            int i = preparedStatement.executeUpdate();

            sql = "delete from employees where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            int j = preparedStatement.executeUpdate();
            connection.setAutoCommit(true);
            if(i !=0 || j != 0){
               System.out.println("操作成功");
            }
            response.sendRedirect(request.getContextPath() + "/dept/List");
         } else if ("/dept/Detail".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath() + "/dept/index.jsp");
            }
            connection.setAutoCommit(false);
            ArrayList arrayList = new ArrayList();
            String department_id = request.getParameter("department_id");
            sql = "select employee_id,last_name,job_id,manager_id,department_id,hiredate from employees where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setInt(1, Integer.parseInt(department_id));
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
               String employee_id= resultSet.getString("employee_id");
               String last_name = resultSet.getString("last_name");
               String job_id = resultSet.getString("job_id");
               String manager_id = resultSet.getString("manager_id");
               department_id = resultSet.getString("department_id");
               String hiredate = resultSet.getString("hiredate");
               EmoloyeeUser emoloyeeUser = new EmoloyeeUser(employee_id,last_name,job_id,manager_id,department_id,hiredate);
               arrayList.add(emoloyeeUser);
            }
            connection.setAutoCommit(true);
            request.setAttribute("detail",arrayList);
            request.getRequestDispatcher("/deptDetail.jsp").forward(request,response);
         } else if ("/dept/Update".equals(request.getServletPath())) {
            HttpSession session = request.getSession(false);
            if(session == null || session.getAttribute("username") == null){
               response.sendRedirect(request.getContextPath() + "/dept/index.jsp");
            }
            connection.setAutoCommit(false);
            String department_id = request.getParameter("department_id");
            System.out.println(department_id);
            String department_name = request.getParameter("department_name");
            String manager_id = request.getParameter("manager_id");
            String city = request.getParameter("city");

            sql = "update departments set department_name = ?,manager_id = ? where department_id = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,department_name);
            preparedStatement.setInt(2, Integer.parseInt(manager_id));
            preparedStatement.setInt(3, Integer.parseInt(department_id));
            int j = preparedStatement.executeUpdate();

            sql = "update locations set city = ? where location_id = (select location_id from departments where department_id = ?)";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,city);
            preparedStatement.setInt(2, Integer.parseInt(department_id));
            int i = preparedStatement.executeUpdate();
            if(i != 0 && j != 0){
               System.out.println("修改成功");
            }
            connection.setAutoCommit(true);

            response.sendRedirect(request.getContextPath() + "/dept/List");
         } else if ("/dept/login".equals(request.getServletPath())) {
            HttpSession session = request.getSession();
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            session.setAttribute("username",username);
            sql = "select * from t_login where username = ? and password = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1,username);
            preparedStatement.setInt(2, Integer.parseInt(password));
            resultSet = preparedStatement.executeQuery();
            if(resultSet.next()){
               System.out.println("登录成功");
               connection.setAutoCommit(true);
               response.sendRedirect(request.getContextPath() + "/dept/List");
            }else {
               System.out.println("登录失败");
            }
         }
   } catch (ClassNotFoundException e) {
         throw new RuntimeException(e);
   } catch (SQLException e) {
         try {
            connection.rollback();
         } catch (SQLException ex) {
            throw new RuntimeException(ex);
         }
         throw new RuntimeException(e);
   }finally {
         if(resultSet != null){
            try {
               resultSet.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
         if(preparedStatement != null){
            try {
               preparedStatement.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
         if(connection != null){
            try {
               connection.close();
            } catch (SQLException e) {
               throw new RuntimeException(e);
            }
         }
   }
}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   doGet(request,response);
}
}

她与晚风 发表于 2023-4-29 22:23:52

歌者文明清理员发表于 2023-4-29 19:00
既然使用重定向方式无法解决问题，那就考虑使用转发的方式代替。

将以下代码：

改了一下加上else就可以了,可我不加else也只会执行一个重定向啊,是编译器看不懂还是什么

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重定向不过去