在類型bean上找不到屬性'EmployeeID'。員工

Question

我試圖在同一個表中顯示所有員工列表，並將其刪除。但是這個錯誤一直困擾着我。其原因是什麼？

May 28, 2017 9:25:27 PM 
org.apache.catalina.core.ApplicationDispatcher invoke 
SEVERE: Servlet.service() for servlet jsp threw exception 
javax.el.PropertyNotFoundException: Property 'EmployeeID' not found on type bean.Employee 

May 28, 2017 9:25:27 PM org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [DisplayAllEmp] in context with path [/ELMS] threw exception [An exception occurred processing JSP page /elms/elms_skms/DeleteEmployeeAcc.jsp at line 55 

52:          <tbody> 
53:           <c:forEach items="${employee}" var="emp"> 
54:            <tr> 
55:             <td><c:out value="${emp.EmployeeID}" /></td> 
56:             <td><c:out value="${emp.EmployeeIC}" /></td> 
57:             <td><c:out value="${emp.EmployeeName}" /></td> 
58:             <td><c:out value="${emp.EmployeePosition}" /></td> 


Stacktrace:] with root cause 
javax.el.PropertyNotFoundException: Property 'EmployeeID' not found on type bean.Employee 
    at javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:266) 
    at javax.el.BeanELResolver$BeanProperties.access$300(BeanELResolver.java:243) 

這是我的jsp頁面：

<div class="module-body table"> 
<form name = delete" method="POST" action="DeleteEmployeeServlet"> 
<table cellpadding="0" cellspacing="0" border="0" class="datatable-1 table 
table-bordered table-striped  display" width="50%"> 

<thead> 
<tr> 
<th>Employee ID</th> 
<th>Employee IC</th> 
<th>Employee Name</th> 
<th>Employee Position</th> 
<th>Employee Session</th> 
<th>Employee Grade</th> 
<th>Action</th> 
</tr> 
</thead> 
<tbody> 
<c:forEach items="${employee}" var="emp"> 
<tr> 
<td><c:out value="${emp.EmployeeID}" /></td> 
<td><c:out value="${emp.EmployeeIC}" /></td> 
<td><c:out value="${emp.EmployeeName}" /></td> 
<td><c:out value="${emp.EmployeePosition}" /></td> 
<td><c:out value="${emp.EmployeeSession}" /></td> 
<td><c:out value="${emp.EmployeeGrade}" /></td> 
<td><a href="DeleteEmployeeServlet?table=employee&employeeid=<c:out 
    value="${emp.EmployeeID}" />"onclick="return confirm('Are you 
    sure?');"><i class="icon-trash"></i></a> <br></td> 
</c:forEach> 
</tbody> 

這是我的servlet頁面：

package servlet; 

import java.io.IOException; 
import java.sql.SQLException; 
import java.util.Date; 

import javax.servlet.RequestDispatcher; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.http.HttpSession; 

import model.EmployeeDAO; 
import bean.Employee; 

public class DeleteEmployeeServlet extends HttpServlet { 
    private static final long serialVersionUID = 1L; 
    private EmployeeDAO dao; 

    public DeleteEmployeeServlet() { 
     super(); 
     dao = new EmployeeDAO(); 
    } 
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     String forward = ""; 
     String table = request.getParameter("table"); 
     if(table.equalsIgnoreCase("employee")){ 
      int id = Integer.parseInt(request.getParameter("EmployeeID")); 
      dao.DeleteEmployeeDetails(id); 
      forward = "DisplayAllEmp?table=employee"; 
     } 
     RequestDispatcher view = request.getRequestDispatcher(forward); 
     view.forward(request, response); 
    } 

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {} 

} 

這裏是我的模型/ DAO（viewEmployee）：

public List<Employee> viewEmployee() { 
     List<Employee> employee = new ArrayList<Employee>(); 
     try { 
      currentCon = ConnectionManager.getConnection(); 
      stmt = currentCon.createStatement(); 
      ResultSet rs = stmt.executeQuery("select * from employee"); 
      while (rs.next()) { 
       Employee e = new Employee(); 
       e.setEmployeeID(rs.getInt("EmployeeID")); 
       e.setEmployeePassword(rs.getString("EmployeePassword")); 
       e.setEmployeeName(rs.getString("EmployeeName")); 
       e.setEmployeeIC(rs.getString("EmployeeIC")); 
       e.setEmployeeGender(rs.getString("EmployeeGender")); 
       e.setEmployeeEmail(rs.getString("EmployeeEmail")); 
       e.setEmployeePhoneNo(rs.getString("EmployeePhoneNo")); 
       e.setEmployeeStreet1(rs.getString("EmployeeStreet1")); 
       e.setEmployeeStreet2(rs.getString("EmployeeStreet2")); 
       e.setEmployeePCode(rs.getInt("EmployeePCode")); 
       e.setEmployeeCity(rs.getString("EmployeeCity")); 
       e.setEmployeeState(rs.getString("EmployeeState")); 
       e.setEmployeeQualification(rs.getString("EmployeeQualification")); 
       e.setEmployeePosition(rs.getString("EmployeePosition")); 
       e.setEmployeeSession(rs.getString("EmployeeSession")); 
       e.setEmployeeGrade(rs.getInt("EmployeeGrade")); 
       e.setEmploymentDate(rs.getDate("EmploymentDate")); 
       employee.add(e); 
       System.out.println("Employee id: " + e.getEmployeeID()); 
      } 
      System.out.println("All rows from table view Employee retrieved!"); 
     } catch (SQLException e) { 
      System.out.println("Failed: An SQL Exception occured : " + e); 
      e.printStackTrace(); 
     } 
     return employee; 
    } 

這是我的DisplayAllEmp的DAO：

public void DeleteEmployeeDetails(int id) { 
     try { 
      currentCon = ConnectionManager.getConnection(); 
      ps = currentCon.prepareStatement("delete from employee where employeeID=?"); 
      // Parameters start with 1 
      ps.setInt(1, id); 
      ps.executeUpdate(); 
      System.out.println("1 row of table Employee has been deleted. employeeID:" + id); 
     } catch (SQLException e) { 
      e.printStackTrace(); 
     } 
    } 

這裏是我的豆（員工）：

package bean; 

import java.util.Date; 

public class Employee { 

    private int EmployeeID; 
    private String EmployeePassword; 
    private String EmployeeName; 
    private String EmployeeIC; 
    private String EmployeeGender; 
    private String EmployeeEmail; 
    private String EmployeePhoneNo; 
    private String EmployeeStreet1; 
    private String EmployeeStreet2; 
    private int EmployeePCode; 
    private String EmployeeCity; 
    private String EmployeeState; 
    private String EmployeeQualification; 
    private String EmployeePosition; 
    private String EmployeeSession; 
    private int EmployeeGrade; 
    private Date EmploymentDate; 
    private boolean valid; 

    public Employee() { 
     EmployeeID = 0; 
     EmployeePassword = null; 
     EmployeeName=null; 
     EmployeeIC=null; 
     EmployeeGender=null; 
     EmployeeEmail=null; 
     EmployeePhoneNo=null; 
     EmployeeStreet1=null; 
     EmployeeStreet2=null; 
     EmployeePCode=0; 
     EmployeeCity=null; 
     EmployeeState=null; 
     EmployeeQualification=null; 
     EmployeePosition=null; 
     EmployeeSession=null; 
     EmployeeGrade=0; 
     EmploymentDate=null; 
    } 

    public Employee(int employeeID, String employeePassword, String employeeName, String employeeIC, String employeeGender, String employeeEmail, String employeePhone, String employeeStreet1, String employeeStreet2, int employeePCode, String employeeCity, String employeeState, String employeeQuaification, String employeePosition, String employeeSession, int employeeGrade, Date employmentDate) { 
     EmployeeID = employeeID; 
     EmployeePassword = employeePassword; 
     EmployeeName=employeeName; 
     EmployeeIC=employeeIC; 
     EmployeeGender=employeeGender; 
     EmployeeEmail=employeeEmail; 
     EmployeePhoneNo=employeePhone; 
     EmployeeStreet1=employeeStreet1; 
     EmployeeStreet2=employeeStreet2; 
     EmployeePCode=employeePCode; 
     EmployeeCity=employeeCity; 
     EmployeeState=employeeState; 
     EmployeeQualification=employeeQuaification; 
     EmployeePosition=employeePosition; 
     EmployeeSession=employeeSession; 
     EmployeeGrade=employeeGrade; 
     EmploymentDate=employmentDate; 
    } 

    public int getEmployeeID() {return EmployeeID;} 
    public void setEmployeeID(int employeeID) {EmployeeID = employeeID;} 

    public String getEmployeePassword() {return EmployeePassword;} 
    public void setEmployeePassword(String employeePassword) {EmployeePassword = employeePassword;} 

    public String getEmployeeName() {return EmployeeName;} 
    public void setEmployeeName(String employeeName) {EmployeeName = employeeName;} 

    public String getEmployeeIC() {return EmployeeIC;} 
    public void setEmployeeIC(String employeeIC) {EmployeeIC = employeeIC;} 

    public String getEmployeeGender() {return EmployeeGender;} 
    public void setEmployeeGender(String employeeGender) {EmployeeGender = employeeGender;} 

    public String getEmployeeEmail() {return EmployeeEmail;} 
    public void setEmployeeEmail(String employeeEmail) {EmployeeEmail = employeeEmail;} 

    public String getEmployeePhoneNo() {return EmployeePhoneNo;} 
    public void setEmployeePhoneNo(String employeePhoneNo) {EmployeePhoneNo = employeePhoneNo;} 

    public String getEmployeeStreet1() {return EmployeeStreet1;} 
    public void setEmployeeStreet1(String employeeStreet1) {EmployeeStreet1 = employeeStreet1;} 

    public String getEmployeeStreet2() {return EmployeeStreet2;} 
    public void setEmployeeStreet2(String employeeStreet2) {EmployeeStreet2 = employeeStreet2;} 

    public int getEmployeePCode() {return EmployeePCode;} 
    public void setEmployeePCode(int employeePCode) {EmployeePCode = employeePCode;} 

    public String getEmployeeCity() {return EmployeeCity;} 
    public void setEmployeeCity(String employeeCity) {EmployeeCity = employeeCity;} 

    public String getEmployeeState() {return EmployeeState;} 
    public void setEmployeeState(String employeeState) {EmployeeState = employeeState;} 

    public String getEmployeeQualification() {return EmployeeQualification;} 
    public void setEmployeeQualification(String employeeQualification) {EmployeeQualification = employeeQualification;} 

    public String getEmployeePosition() {return EmployeePosition;} 
    public void setEmployeePosition(String employeePosition) {EmployeePosition = employeePosition;} 

    public String getEmployeeSession() {return EmployeeSession;} 
    public void setEmployeeSession(String employeeSession) {EmployeeSession = employeeSession;} 

    public int getEmployeeGrade() {return EmployeeGrade;} 
    public void setEmployeeGrade(int employeeGrade) {EmployeeGrade = employeeGrade;} 

    public Date getEmploymentDate() {return EmploymentDate;} 
    public void setEmploymentDate(Date employmentDate) {EmploymentDate = employmentDate;} 

    public boolean isValid() {return valid;} 
    public void setValid(boolean valid) {this.valid = valid;} 

} 

Answer 1

你Employee類僅有私有字段，因此你不能使用點符號訪問它們。 setters和getters是公開的，並且可以在課外訪問。使用它們來檢索jsp文件中所需的信息。

此外，請看Oracle的文檔頁面Declaring Member Variables，部分Access Modifiers。

• 公衆的改質場是所有類訪問。

• 私人修飾符 - 該字段只能在其自己的類中訪問。

當你寫${emp.EmployeeID}，你所要求的一個名爲EmployeeID領域具有public訪問修飾符，它不存在。