jsp mysql 實現客戶端資料的改變

dao.impl

import com.mchange.v2.c3p0.ComboPooledDataSource;
import day13.dao.StudentDao;
import day13.entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import javax.sql.DataSource;
import java.sql.SQLException;
import java.util.List;

public class StudentDaoImpl implements StudentDao {   //這兩句一定記住 實現
    private DataSource ds =  new ComboPooledDataSource();
    private QueryRunner qr = new QueryRunner(ds);  //這兩句一定記住

    public List<Student> selectAll(){
        List<Student> studentList = null;
        try {
            String sql ="select * from test1";
            studentList = qr.query(sql,new BeanListHandler<Student>(Student.class));  //小寫 query  //這兩句一定記住
        } catch (Exception e) {
            e.printStackTrace();
        }
        return studentList;
    }

    public Student selectByPid(int pid){
        Student student = null;
        try {
            String sql = "select * from test1 where pid = ?";
            student = qr.query(sql,new BeanHandler<Student>(Student.class),pid);   //Student.class 是什麼？
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return student;
    }

    @Override
    public int updateStudent(Student student) {
        int num = 0;

        try {
            String sql = "update test1 set pname =?,page=? where pid = ?";
            Object[] objects = {student.getPname(),student.getPage(),student.getPid()};
            num = qr.update(sql,objects);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return num;
    }

    @Override
    public int deleteById(int pid) {
        int num = 0;
        String sql = "delete from test1 where pid = ?";
        try {
            num = qr.update(sql,pid);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return num;

    }

    @Override
    public int addStudent(Student student) {
        int num = 0;
        try {
            String sql = "insert into test1(pname,page)values(?,?)";
            Object[] objects = {student.getPname(),student.getPage()};
            num = qr.update(sql,objects);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return num;
    }
}
 

dao

import day13.entity.Student;

import java.util.List;

public interface StudentDao {
    List<Student> selectAll();  //僅定義型別（一定記住的）
    Student selectByPid(int pid);
    int updateStudent(Student student);
    int deleteById(int pid);
    int addStudent(Student student);
}

entity

import java.io.Serializable;

public class Student implements Serializable {  //這句一定記住 實現
    private int pid;        //這句一定記住 兩構造 get set toString
    private int page;   // int  型 所以後面都要轉型
    private String pname;
 

service.ServiceImpl

import day13.dao.StudentDao;
import day13.dao.impl.StudentDaoImpl;
import day13.entity.Student;
import day13.service.StudentService;

import java.util.List;

public class StudentServiceImpl implements StudentService {  //這兩句一定記住  實現
    private StudentDao studentDao = new StudentDaoImpl();  //這句一定記住  例項後，才能使用

    public List<Student> selectAll(){
        return studentDao.selectAll();
    }

    @Override
    public Student selectByPid(int pid) {
        return studentDao.selectByPid(pid);  //對 Dao 的 ？？
    }

    @Override
    public int updateStudent(Student student) {
        return studentDao.updateStudent(student);
    }

    @Override
    public int deleteById(int pid) {
        return studentDao.deleteById(pid);
    }

    @Override
    public int addStudent(Student student) {
        return studentDao.addStudent(student);
    }

}
 

servlet

import day13.entity.Student;
import day13.service.ServiceImpl.StudentServiceImpl;
import day13.service.StudentService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

//錯誤：
//        update寫錯；未標記pid 傳入值；未標記flag 改變狀態；page 是int 型別；給問號賦值的 student.getPage() 順序錯誤；

@WebServlet(name = "studentServlet",urlPatterns = "/studentServlet")
public class StudentServlet extends HttpServlet {
    private StudentService studentService ;

    @Override
    public void init() throws ServletException {
        studentService = new StudentServiceImpl();  //介面
    }

    @Override  //增加修改id功能
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=UTF-8");
        String flag = req.getParameter("flag");
        //查詢
        if ("goUpdate".equals(flag)){
            String pidStr = req.getParameter("pid");
            Student student = studentService.selectByPid(Integer.parseInt(pidStr));
            req.setAttribute("student",student);
            req.getRequestDispatcher("update.jsp").forward(req,resp);

            //修改
        }else if("update".equals(flag)){
            //獲取前端傳遞的引數
            String pid = req.getParameter("pid");
            String pname = req.getParameter("pname");
            String page = req.getParameter("page");
            //呼叫service 層 的方法
            Student student  = new Student(Integer.parseInt(pid),Integer.parseInt(page),pname);
            int num =  studentService.updateStudent(student);
            //成功
            if(num>0){
                //跳轉回首頁
                resp.sendRedirect("index.jsp");
            }else{
                //重定向來傳遞引數

                resp.sendRedirect("studentServlet?flag=goUpdate&pid="+pid);
            }
//            刪除
        }else if ("delete".equals(flag)){
            String pidStr = req.getParameter("pid");  //獲取前端傳遞的引數
            int num = studentService.deleteById(Integer.parseInt(pidStr));  //呼叫 service 方法
            resp.sendRedirect("index.jsp");  //刪除成功，跳轉到首頁

//          增加頁面
        }else if("goAdd".equals(flag)){
            req.getRequestDispatcher("add.jsp").forward(req,resp);
//            增加功能
        }else if("add".equals(flag)){
            String pname = req.getParameter("pname");
            int page = Integer.parseInt(req.getParameter("page"));

            Student student = new Student();
            student.setPname(pname);
            student.setPage(page);  //幹啥的？
            int num = studentService.addStudent(student);
            if(num>0){
                //跳轉回首頁
                resp.sendRedirect("index.jsp");
            }else{
                //重定向來傳遞引數
                resp.sendRedirect("studentServlet?flag=goAdd");
            }
        }

        else {
                //顯示
             List<Student> studentList =studentService.selectAll();
             req.setAttribute("studentList",studentList);
             req.getRequestDispatcher("index.jsp").forward(req,resp);
        }
    }

}

add.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>新增</title>
</head>
<body>
<form method="post" action="studentServlet">
    <input type="hidden" name="flag" value="add">  //提交後 ，flag 成 add
    <p><input type="text" name="pname" value=""></p>
    <p><input type="text" name="page" value=""></p>
    <input type="submit" value="增加">

</form>
</body>
</html>

index.jsp

<%@ page import="java.util.List" %>
<%@ page import="day13.entity.Student" %>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>首頁</title>
  </head>
  <body>
  <%
      List<Student> studentList = null;
      if (request.getAttribute("studentList")==null){
          request.getRequestDispatcher("studentServlet").forward(request,response);
          return;
      }else {
          studentList = (List<Student>) request.getAttribute("studentList");
          System.out.println();
      }

      %>

  <%--增加頁面--%>
  <h1 id="tv_h1" onclick="showInfo()">增加</h1>
  <script>
      function showInfo() {
          window.location.href="studentServlet?flag=goAdd"
      }
  </script>

<%--  主頁面--%>
<table border="1px" width="700px" align="center">
  <tr>
      <td>編號</td>
      <td>姓名</td>
      <td>年齡</td>
  </tr>

<%
    for (int i = 0 ;i<studentList.size();i++){
%>
      <tr>
        <td><%=studentList.get(i).getPid()%></td>
        <td><%=studentList.get(i).getPname()%></td>
         <td><%=studentList.get(i).getPage()%></td>
          <td><a href="studentServlet?pid=<%=studentList.get(i).getPid()%>&flag=goUpdate">修改</a></td>
          <td><a href="studentServlet?pid=<%=studentList.get(i).getPid()%>&flag=delete">刪除</a></td>
      </tr>

                  <%
                      }
                  %>

              </table>

  </body>
</html>

update.jsp

<%@ page import="day13.entity.Student" %>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>更新</title>
</head>
<body>

<%
    Student student = (Student) request.getAttribute("student");
%>

<form method="post" action="studentServlet">
<%--    jsp <%%> 內不允許有符號。所以變數才用 <%%> --%>
<%--    <p><input type="hidden" name="flag" value="update"></p>--%>
    <input type="hidden" name="flag" value="update">
    <input type="hidden" name="pid" value="<%=student.getPid()%>">  <%--困惱20分鐘的地方--%>
    <p><input type="text" name="pname" value="<%=student.getPname()%>"></p>
    <p><input type="text" name="page" value="<%=student.getPage()%>"></p>
    <p><input type="submit" value="提交"></p>
</form>

</body>
</html>

結果展示：

————————主介面：

————————資料修改

————————修改成功

————————刪除

————————增加

————————增加成功