javax.el.MethodNotFoundException : Method not found: JSP

Question

在编译 JSP 模板期间，出现以下异常:

getFriendImage() is not a method

我尝试过重建类(class)，但没有结果。 src 内的元素是一个可以正常工作的图像的链接。

package classes;

public class Friends {

  private String username;
  private String friendname;
  private String complete;
  private String datestring;
  private String user_image;
  private String friendImage;
  private String online;

  public Friends(String username, String friendname, String complete, 
                 String datestring, String user_image, 
                 String friendImage, String online) {
    this.username = username;
    this.friendname = friendname;
    this.complete = complete;
    this.datestring = datestring;
    this.user_image = user_image;
    this.friendImage = friendImage;
    this.online = online;
  }

  public String getUsername() {
    return username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

  public String getFriendname() {
    return friendname;
  }

  public void setFriendname(String friendname) {
    this.friendname = friendname;
  }

  public String getComplete() {
    return complete;
  }

  public void setComplete(String complete) {
    this.complete = complete;
  }

  public String getDatestring() {
    return datestring;
  }

  public void setDatestring(String datestring) {
    this.datestring = datestring;
  }

  public String getUser_image() {
    return user_image;
  }

  public void setUser_image(String user_image) {
    this.user_image = user_image;
  }

  public String getFriendImage() {
    return friendImage;
  }

  public void setFriendImage(String friendImage) {
    this.friendImage = friendImage;
  }

  public String getOnline() {
    return online;
  }

  public void setOnline(String online) {
    this.online = online;
  }
}

 session.setAttribute("friendsList", friendsList);

JSP 模板

<ul id="friends_list">
    <c:forEach var="item" items="${friendsList}">
        <li class="friend_item"><img class="friend_list_image" 
            src="${friendsList.getFriendImage()}"  
            alt="friend_image"/>
            <label>${friendsList.getFriendname()}</label>
            <img class="message_icon" src="Images/Message.png" 
                 alt="Message_Icon" title="Message" onclick="message_friend()"/>
        </li>
    </c:forEach>
</ul>

Answer 1

您通常不应该像这样访问这些方法。通常，您应该做的就是使用您在 Friends 类中声明的字段名称来访问它们，前提是您事先设置了这些变量。

此外，如果您提供var="item"在你的<c:forEach那么你应该使用 ${item.somefieldname} 访问它们

<ul id="friends_list">
    <c:forEach var="item" items="${friendsList}">
        <li class="friend_item">
         <img class="friend_list_image" src="${item.friendImage}" alt="friend_image"/>
         <label>${item.friendname}</label>
         <img class="message_icon" src="Images/Message.png" alt="Message_Icon" title="Message" onclick="message_friend()"/>
        </li>
    </c:forEach>
</ul>

另请注意大小写:

  private String username;
  private String friendname;
  private String complete;
  private String datestring;
  private String user_image;
  private String friendImage; //capitalized here, be careful!
  private String online;