Java Struts2<；迭代器>；随机复制值

使用的技术：Struts2、JPA（EclipseLink）、ApacheDerby数据库

我的项目位于映像宿主上，我已将

UserEntity

（父项）配置为包含对

ImageEntity

的引用

我有一个名为

userEntity

的会话变量，它是登录时获取的用户对象。JSP页面

myUploads.JSP

使用用户对象中的列表并显示所有值。我已经使用struts迭代器标记

来循环

列表

问题:

通过

随机复制行

注意：我已经检查了数据库，它没有重复，可以观察到重复的条目共享相同的图像ID

JSP代码：

<table border="1">
        <thead>
            <tr>
                <th>Name</th>
                <th>Comments</th>
                <th>Link</th>
                <th>Image</th>
                <th>Delete image</th>
                <th>Share details</th>
            </tr>
        </thead>
        <tbody>
            <s:iterator value="#session.userEntity.images" var="image">

                <s:url id="imageURL" action="myUploads" >
                    <s:param name="imageID" value="#image.id"></s:param>
                </s:url>

                <s:url id="deleteImageURL" action="deleteImage" method="deleteImage">
                    <s:param name="imageID" value="#image.id"></s:param>
                </s:url>
                 <tr>
                        <td><s:property value="#image.name"/></td>
                        <td><s:property value="#image.comments"/></td>
                        <td><s:a href="%{imageURL}" cssClass="linkStyle">
                                <s:property value="#image.imageName"/>
                            </s:a></td>
                        <td>
                           <s:a href="%{imageURL}" cssClass="linkStyle"> <img width="200" height="200" src="<s:url action='ImageAction'><s:param name='imageID' value="#image.id"></s:param></s:url>" /> </s:a></td>
                        <td>
                            <s:a href="%{deleteImageURL}" cssClass="linkStyle">
                                Delete
                            </s:a>   </td>
                        <td>
                           <s:if test="%{#image.shares != null}">
                               <ul> 
                               <s:iterator value="#image.shares" var="share">
                                   <li><s:property value="#share.fullName"/></li>
                               </s:iterator>
                               </ul>
                           </s:if>
                        </td>
                    </tr>

            </s:iterator>
        </tbody>
    </table>

<table border="1">
        <thead>
            <tr>
                <th>Name</th>
                <th>Comments</th>
                <th>Link</th>
                <th>Image</th>
                <th>Delete image</th>
                <th>Share details</th>
            </tr>
        </thead>
        <tbody>

                ROW 1 : imageID=151
                    <tr>
                        <td>sun</td>
                        <td>sun set</td>
                        <td><a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle">
                                Sunset.jpg
                            </a></td>
                        <td>
                           <a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle"> <img width="200" height="200" src="/ImageHosting5.7/ImageAction.action?imageID=151" /> </a></td>
                        <td>
                            <a href="/ImageHosting5.7/deleteImage!deleteImage.action?imageID=151" class="linkStyle">
                                Delete
                            </a>   </td>
                        <td>

                               <ul> 

                                   <li>b</li>

                               </ul>

                        </td>
                    </tr>


             ROW 2 : imageID=151
                    <tr>
                        <td>sun</td>
                        <td>sun set</td>
                        <td><a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle">
                                Sunset.jpg
                            </a></td>
                        <td>
                           <a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle"> <img width="200" height="200" src="/ImageHosting5.7/ImageAction.action?imageID=151" /> </a></td>
                        <td>
                            <a href="/ImageHosting5.7/deleteImage!deleteImage.action?imageID=151" class="linkStyle">
                                Delete
                            </a>   </td>
                        <td>

                               <ul> 

                                   <li>b</li>

                               </ul>

                        </td>
                    </tr>


        </tbody>
    </table>

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id; --------> UNIQUE

private String name;
private String comments;

@ManyToOne
private UserEntity userEntity;

private String imagePath;    
private String imageName;

@ManyToMany(cascade = CascadeType.MERGE)
private List<UserEntity> shares; // list of owner IDs

private Boolean publicShare; // isShared 

private boolean addImage()
{       
    DatabaseService db;       
    try {
        db = new DatabaseService();           

        // get userEntity from session
        Map sessionMap = ActionContext.getContext().getSession();
        userEntity = (UserEntity) sessionMap.get("userEntity");

        // save image to file system
        String filePath = servletRequest.getSession().getServletContext().getRealPath("/images");          
        File fileToCreate = new File(filePath, this.uploadFileFileName);
        FileUtils.copyFile(this.uploadFile, fileToCreate);

        // make imageEntity
        imageEntity = new ImageEntity();
        imageEntity.setName(name);
        imageEntity.setComments(comments);
        imageEntity.setUserEntity(userEntity);

        try {
            if(!userShare.isEmpty())
             imageEntity.setShares(new DatabaseService().findUserEntitysByUsernames(users));
        } catch (Exception e) {
          Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
        }

        imageEntity.setImagePath(fileToCreate.getAbsolutePath());
        imageEntity.setImageName(fileToCreate.getName());           
        db.persist(imageEntity);           
        userEntity.addToImages(imageEntity);           

        // update userEntity                      
        userEntity = (UserEntity) db.merge(userEntity);

        // update sessionMap
        sessionMap.put("userEntity", userEntity);

        // notify share
        if( ! imageEntity.getShares().isEmpty())
        {               
            // init mail
            SendMailService sendMailService = new SendMailService();
            sendMailService.setBody("Image is shared with you");
            sendMailService.setSubject("DJVT IMAGE HOSTING");

            for (UserEntity ue : imageEntity.getShares()) {
                sendMailService.setTo(ue.getEmailid());
            }

            sendMailService.sendMail();
        }           
    } catch (Exception e) {
        throw new RuntimeException("img upload failed" + e.toString());
    }

    return true; // success
}

图像的实体类：

<table border="1">
        <thead>
            <tr>
                <th>Name</th>
                <th>Comments</th>
                <th>Link</th>
                <th>Image</th>
                <th>Delete image</th>
                <th>Share details</th>
            </tr>
        </thead>
        <tbody>
            <s:iterator value="#session.userEntity.images" var="image">

                <s:url id="imageURL" action="myUploads" >
                    <s:param name="imageID" value="#image.id"></s:param>
                </s:url>

                <s:url id="deleteImageURL" action="deleteImage" method="deleteImage">
                    <s:param name="imageID" value="#image.id"></s:param>
                </s:url>
                 <tr>
                        <td><s:property value="#image.name"/></td>
                        <td><s:property value="#image.comments"/></td>
                        <td><s:a href="%{imageURL}" cssClass="linkStyle">
                                <s:property value="#image.imageName"/>
                            </s:a></td>
                        <td>
                           <s:a href="%{imageURL}" cssClass="linkStyle"> <img width="200" height="200" src="<s:url action='ImageAction'><s:param name='imageID' value="#image.id"></s:param></s:url>" /> </s:a></td>
                        <td>
                            <s:a href="%{deleteImageURL}" cssClass="linkStyle">
                                Delete
                            </s:a>   </td>
                        <td>
                           <s:if test="%{#image.shares != null}">
                               <ul> 
                               <s:iterator value="#image.shares" var="share">
                                   <li><s:property value="#share.fullName"/></li>
                               </s:iterator>
                               </ul>
                           </s:if>
                        </td>
                    </tr>

            </s:iterator>
        </tbody>
    </table>

<table border="1">
        <thead>
            <tr>
                <th>Name</th>
                <th>Comments</th>
                <th>Link</th>
                <th>Image</th>
                <th>Delete image</th>
                <th>Share details</th>
            </tr>
        </thead>
        <tbody>

                ROW 1 : imageID=151
                    <tr>
                        <td>sun</td>
                        <td>sun set</td>
                        <td><a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle">
                                Sunset.jpg
                            </a></td>
                        <td>
                           <a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle"> <img width="200" height="200" src="/ImageHosting5.7/ImageAction.action?imageID=151" /> </a></td>
                        <td>
                            <a href="/ImageHosting5.7/deleteImage!deleteImage.action?imageID=151" class="linkStyle">
                                Delete
                            </a>   </td>
                        <td>

                               <ul> 

                                   <li>b</li>

                               </ul>

                        </td>
                    </tr>


             ROW 2 : imageID=151
                    <tr>
                        <td>sun</td>
                        <td>sun set</td>
                        <td><a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle">
                                Sunset.jpg
                            </a></td>
                        <td>
                           <a href="/ImageHosting5.7/myUploads.action?imageID=151" class="linkStyle"> <img width="200" height="200" src="/ImageHosting5.7/ImageAction.action?imageID=151" /> </a></td>
                        <td>
                            <a href="/ImageHosting5.7/deleteImage!deleteImage.action?imageID=151" class="linkStyle">
                                Delete
                            </a>   </td>
                        <td>

                               <ul> 

                                   <li>b</li>

                               </ul>

                        </td>
                    </tr>


        </tbody>
    </table>

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id; --------> UNIQUE

private String name;
private String comments;

@ManyToOne
private UserEntity userEntity;

private String imagePath;    
private String imageName;

@ManyToMany(cascade = CascadeType.MERGE)
private List<UserEntity> shares; // list of owner IDs

private Boolean publicShare; // isShared 

private boolean addImage()
{       
    DatabaseService db;       
    try {
        db = new DatabaseService();           

        // get userEntity from session
        Map sessionMap = ActionContext.getContext().getSession();
        userEntity = (UserEntity) sessionMap.get("userEntity");

        // save image to file system
        String filePath = servletRequest.getSession().getServletContext().getRealPath("/images");          
        File fileToCreate = new File(filePath, this.uploadFileFileName);
        FileUtils.copyFile(this.uploadFile, fileToCreate);

        // make imageEntity
        imageEntity = new ImageEntity();
        imageEntity.setName(name);
        imageEntity.setComments(comments);
        imageEntity.setUserEntity(userEntity);

        try {
            if(!userShare.isEmpty())
             imageEntity.setShares(new DatabaseService().findUserEntitysByUsernames(users));
        } catch (Exception e) {
          Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
        }

        imageEntity.setImagePath(fileToCreate.getAbsolutePath());
        imageEntity.setImageName(fileToCreate.getName());           
        db.persist(imageEntity);           
        userEntity.addToImages(imageEntity);           

        // update userEntity                      
        userEntity = (UserEntity) db.merge(userEntity);

        // update sessionMap
        sessionMap.put("userEntity", userEntity);

        // notify share
        if( ! imageEntity.getShares().isEmpty())
        {               
            // init mail
            SendMailService sendMailService = new SendMailService();
            sendMailService.setBody("Image is shared with you");
            sendMailService.setSubject("DJVT IMAGE HOSTING");

            for (UserEntity ue : imageEntity.getShares()) {
                sendMailService.setTo(ue.getEmailid());
            }

            sendMailService.sendMail();
        }           
    } catch (Exception e) {
        throw new RuntimeException("img upload failed" + e.toString());
    }

    return true; // success
}

我该如何解决我的错误，顺便问一下，你对这个错误有什么看法（如果我犯了愚蠢的错误，也有错误）

我登出并登录到我的应用程序，复制一次就消失了

我如何解决我的错误，顺便问一下，你的看法是什么 此错误（如果我犯了愚蠢的错误，则为错误）

共享会话中迭代的集合时出现的问题。因此，其他操作可能会在执行结果之前更新此集合。要检查这一点，您可以在方法中检查重复项。确保堆栈上有替换

工作流的

拦截器

如果将默认主题更改为

<constant name="struts.ui.theme" value="simple"/>

---

在

struts.xml

或使用

css\u xhtml

主题中。

向我们展示操作、返回到客户端的对象，以及在将数据发送到视图之前为证明没有任何重复而进行的测试。my session变量中存在一些问题。。如果没有更多信息，我会正确检查并返回。这将无法提供帮助。我已登录到我的应用程序，并且有一次复制消失了。。我自己也感到困惑：（如果您使用连接，可能是数据库查询的问题，在这种情况下，将有重复的条目