智能协同云图库项目教程 - 图片协同编辑 - 后端改造策略模式

2025-03-13 11:07

阅读984

2025-03-13 11:07

阅读 984

目录结构

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text
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websocket/
├── handler/
│   ├── PictureEditHandler.java
│   └── WsHandshakeInterceptor.java
├── model/
│   ├── enums/
│   │   ├── PictureEditActionEnum.java
│   │   └── PictureEditMessageTypeEnum.java
│   ├── PictureEditRequestMessage.java
│   └── PictureEditResponseMessage.java
├── strategy/
│   ├── impl/
│   │   ├── EditActionMessageStrategy.java
│   │   ├── EnterEditMessageStrategy.java
│   │   ├── ErrorMessageStrategy.java
│   │   └── ExitEditMessageStrategy.java
│   ├── PictureEditMessageStrategy.java
│   └── PictureEditMessageStrategyFactory.java
└── util/
    ├── PictureEditBroadcaster.java
    └── PictureEditingStatusManager.java

核心代码实现

策略接口

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java
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/**
 * @author tt
 * @date 2025/3/13 09:50
 * 图片编辑消息处理策略
 */
public interface PictureEditMessageStrategy {

    /**
     * 处理图片编辑请求消息
     *
     * @param requestMessage 图片编辑请求消息
     * @param session        WebSocket会话
     * @param user           用户信息
     * @param pictureId      图片ID
     * @throws Exception 处理异常
     */
    void handle(PictureEditRequestMessage requestMessage, WebSocketSession session, User user, Long pictureId) throws Exception;

}

策略实现类

EnterEditMessageStrategy.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:51
 * 进入编辑图片状态
 */
@Component
public class EnterEditMessageStrategy implements PictureEditMessageStrategy {

    @Resource
    private UserService userService;

    @Resource
    private PictureEditBroadcaster broadcaster;

    @Resource
    private PictureEditingStatusManager statusManager;

    /**
     * 处理图片编辑请求消息
     *
     * @param requestMessage 图片编辑请求消息
     * @param session        WebSocket会话
     * @param user           用户信息
     * @param pictureId      图片ID
     */
    @Override
    public void handle(PictureEditRequestMessage requestMessage, WebSocketSession session, User user, Long pictureId) throws Exception {
        // 没有用户正在编辑该图片，才能进入编辑
        if (!statusManager.isBeingEdited(pictureId)) {
            // 设置当前用户为编辑用户
            statusManager.setEditingUser(pictureId, user.getId());
            PictureEditResponseMessage responseMessage = new PictureEditResponseMessage();
            responseMessage.setType(PictureEditMessageTypeEnum.ENTER_EDIT.getValue());
            String message = String.format("%s开始编辑图片", user.getUserName());
            responseMessage.setMessage(message);
            responseMessage.setUser(userService.getUserVO(user));
            broadcaster.broadcastToPicture(pictureId, responseMessage);
        }
    }

}

EditActionMessageStrategy.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:52
 * 执行编辑操作
 */
@Component
public class EditActionMessageStrategy implements PictureEditMessageStrategy {

    @Resource
    private UserService userService;

    @Resource
    private PictureEditBroadcaster broadcaster;

    @Resource
    private PictureEditingStatusManager statusManager;

    /**
     * 处理图片编辑请求消息
     *
     * @param requestMessage 图片编辑请求消息
     * @param session        WebSocket会话
     * @param user           用户信息
     * @param pictureId      图片ID
     */
    @Override
    public void handle(PictureEditRequestMessage requestMessage, WebSocketSession session, User user, Long pictureId) throws Exception {
        Long editingUserId = statusManager.getEditingUser(pictureId);
        String editAction = requestMessage.getEditAction();
        PictureEditActionEnum actionEnum = PictureEditActionEnum.getEnumByValue(editAction);
        if (actionEnum == null) {
            return;
        }
        // 确认是当前编辑者
        if (editingUserId != null && editingUserId.equals(user.getId())) {
            PictureEditResponseMessage responseMessage = new PictureEditResponseMessage();
            responseMessage.setType(PictureEditMessageTypeEnum.EDIT_ACTION.getValue());
            String message = String.format("%s执行%s", user.getUserName(), actionEnum.getText());
            responseMessage.setMessage(message);
            responseMessage.setEditAction(editAction);
            responseMessage.setUser(userService.getUserVO(user));
            // 广播给除了当前客户端之外的其他用户，否则会造成重复编辑
            broadcaster.broadcastToPicture(pictureId, responseMessage, session);
        }
    }

}

ExitEditMessageStrategy.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:52
 * 退出编辑图片状态
 */
@Component
public class ExitEditMessageStrategy implements PictureEditMessageStrategy {

    @Resource
    private UserService userService;

    @Resource
    private PictureEditBroadcaster broadcaster;

    @Resource
    private PictureEditingStatusManager statusManager;

    /**
     * 处理图片编辑请求消息
     *
     * @param requestMessage 图片编辑请求消息
     * @param session        WebSocket会话
     * @param user           用户信息
     * @param pictureId      图片ID
     */
    @Override
    public void handle(PictureEditRequestMessage requestMessage, WebSocketSession session, User user, Long pictureId) throws Exception {
        Long editingUserId = statusManager.getEditingUser(pictureId);
        if (editingUserId != null && editingUserId.equals(user.getId())) {
            // 移除当前用户的编辑状态
            statusManager.removeEditingUser(pictureId);
            // 构造响应，发送退出编辑的消息通知
            PictureEditResponseMessage responseMessage = new PictureEditResponseMessage();
            responseMessage.setType(PictureEditMessageTypeEnum.EXIT_EDIT.getValue());
            String message = String.format("%s退出编辑图片", user.getUserName());
            responseMessage.setMessage(message);
            responseMessage.setUser(userService.getUserVO(user));
            broadcaster.broadcastToPicture(pictureId, responseMessage);
        }
    }

}

ErrorMessageStrategy.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:53
 * 消息类型错误处理
 */
@Component
public class ErrorMessageStrategy implements PictureEditMessageStrategy {

    @Resource
    private UserService userService;

    /**
     * 处理图片编辑请求消息
     *
     * @param requestMessage 图片编辑请求消息
     * @param session        WebSocket会话
     * @param user           用户信息
     * @param pictureId      图片ID
     */
    @Override
    public void handle(PictureEditRequestMessage requestMessage, WebSocketSession session, User user, Long pictureId) throws Exception {
        PictureEditResponseMessage responseMessage = new PictureEditResponseMessage();
        responseMessage.setType(PictureEditMessageTypeEnum.ERROR.getValue());
        responseMessage.setMessage("消息类型错误");
        responseMessage.setUser(userService.getUserVO(user));
        session.sendMessage(new TextMessage(JSONUtil.toJsonStr(responseMessage)));
    }

}

策略工厂

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java
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/**
 * @author tt
 * @date 2025/3/13 09:54
 * 消息处理策略工厂
 */
@Component
public class PictureEditMessageStrategyFactory {

    private final Map<String, PictureEditMessageStrategy> strategies = new HashMap<>();

    @Resource
    private EnterEditMessageStrategy enterEditMessageStrategy;

    @Resource
    private EditActionMessageStrategy editActionMessageStrategy;

    @Resource
    private ExitEditMessageStrategy exitEditMessageStrategy;

    @Resource
    private ErrorMessageStrategy errorMessageStrategy;

    @PostConstruct
    public void init() {
        strategies.put(PictureEditMessageTypeEnum.ENTER_EDIT.getValue(), enterEditMessageStrategy);
        strategies.put(PictureEditMessageTypeEnum.EDIT_ACTION.getValue(), editActionMessageStrategy);
        strategies.put(PictureEditMessageTypeEnum.EXIT_EDIT.getValue(), exitEditMessageStrategy);
    }

    /**
     * 获取消息处理策略
     *
     * @param type 消息类型
     * @return 消息处理策略
     */
    public PictureEditMessageStrategy getStrategy(String type) {
        return strategies.getOrDefault(type, errorMessageStrategy);
    }

}

工具类

PictureEditBroadcaster.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:54
 */
@Component
public class PictureEditBroadcaster {

    // 保存所有连接的会话，key: pictureId, value: 用户会话集合
    private final Map<Long, Set<WebSocketSession>> pictureSessions = new ConcurrentHashMap<>();

    public void addSession(Long pictureId, WebSocketSession session) {
        pictureSessions.putIfAbsent(pictureId, ConcurrentHashMap.newKeySet());
        pictureSessions.get(pictureId).add(session);
    }

    public void removeSession(Long pictureId, WebSocketSession session) {
        Set<WebSocketSession> sessionSet = pictureSessions.get(pictureId);
        if (sessionSet != null) {
            sessionSet.remove(session);
            if (sessionSet.isEmpty()) {
                pictureSessions.remove(pictureId);
            }
        }
    }

    /**
     * 广播消息给同一张图片的所有用户
     *
     * @param pictureId                  图片 ID
     * @param pictureEditResponseMessage 图片编辑响应消息
     * @param excludeSession             排除的会话
     */
    public void broadcastToPicture(Long pictureId, PictureEditResponseMessage pictureEditResponseMessage, WebSocketSession excludeSession) throws Exception {
        Set<WebSocketSession> sessionSet = pictureSessions.get(pictureId);
        if (CollUtil.isNotEmpty(sessionSet)) {
            ObjectMapper objectMapper = new ObjectMapper();
	            // 配置序列化：将 Long 类型转为 String，解决丢失精度问题
            SimpleModule module = new SimpleModule();
            module.addSerializer(Long.class, ToStringSerializer.instance);
            module.addSerializer(Long.TYPE, ToStringSerializer.instance); // 支持 long 基本类型
            objectMapper.registerModule(module);
            // 序列化为 JSON 字符串
            String message = objectMapper.writeValueAsString(pictureEditResponseMessage);
            TextMessage textMessage = new TextMessage(message);
            for (WebSocketSession session : sessionSet) {
                // 排除掉的 session 不发送
                if (excludeSession != null && excludeSession.equals(session)) {
                    continue;
                }
                if (session.isOpen()) {
                    session.sendMessage(textMessage);
                }
            }
        }
    }

    // 全部广播
    public void broadcastToPicture(Long pictureId, PictureEditResponseMessage pictureEditResponseMessage) throws Exception {
        broadcastToPicture(pictureId, pictureEditResponseMessage, null);
    }

}

PictureEditingStatusManager.java

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java
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/**
 * @author tt
 * @date 2025/3/13 09:55
 * 图片编辑状态管理器
 */
@Component
public class PictureEditingStatusManager {

    // 每张图片的编辑状态，key: pictureId, value: 当前正在编辑的用户 ID
    private final Map<Long, Long> pictureEditingUsers = new ConcurrentHashMap<>();

    public boolean isBeingEdited(Long pictureId) {
        return pictureEditingUsers.containsKey(pictureId);
    }

    public Long getEditingUser(Long pictureId) {
        return pictureEditingUsers.get(pictureId);
    }

    public void setEditingUser(Long pictureId, Long userId) {
        pictureEditingUsers.put(pictureId, userId);
    }

    public void removeEditingUser(Long pictureId) {
        pictureEditingUsers.remove(pictureId);
    }
}

主WebSocket处理器

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java
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/**
 * @author tt
 * @date 2025/3/13 09:37
 * 图片编辑 WebSocket 处理器
 */
@Component
public class PictureEditHandler extends TextWebSocketHandler {

    @Resource
    private UserService userService;

    @Resource
    private PictureEditBroadcaster broadcaster;

    @Resource
    private PictureEditMessageStrategyFactory strategyFactory;

    /**
     * 连接建立成功后触发
     *
     * @param session 会话
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        // 保存会话到集合中
        User user = (User) session.getAttributes().get("user");
        Long pictureId = (Long) session.getAttributes().get("pictureId");
        broadcaster.addSession(pictureId, session);

        // 构造响应
        PictureEditResponseMessage pictureEditResponseMessage = new PictureEditResponseMessage();
        pictureEditResponseMessage.setType(PictureEditMessageTypeEnum.INFO.getValue());
        String message = String.format("%s加入编辑", user.getUserName());
        pictureEditResponseMessage.setMessage(message);
        pictureEditResponseMessage.setUser(userService.getUserVO(user));
        // 广播给同一张图片的用户
        broadcaster.broadcastToPicture(pictureId, pictureEditResponseMessage);
    }

    /**
     * 处理文本消息
     *
     * @param session 会话
     * @param message 消息
     */
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        // 将消息解析为 PictureEditMessage
        PictureEditRequestMessage pictureEditRequestMessage = JSONUtil.toBean(message.getPayload(), PictureEditRequestMessage.class);
        String type = pictureEditRequestMessage.getType();

        // 从 Session 属性中获取公共参数
        Map<String, Object> attributes = session.getAttributes();
        User user = (User) attributes.get("user");
        Long pictureId = (Long) attributes.get("pictureId");

        // 获取并执行对应的策略
        PictureEditMessageStrategy strategy = strategyFactory.getStrategy(type);
        strategy.handle(pictureEditRequestMessage, session, user, pictureId);
    }

    /**
     * WebSocket 连接关闭时触发
     *
     * @param session 会话
     * @param status  关闭状态
     */
    @Override
    public void afterConnectionClosed(WebSocketSession session, @NotNull CloseStatus status) throws Exception {
        Map<String, Object> attributes = session.getAttributes();
        Long pictureId = (Long) attributes.get("pictureId");
        User user = (User) attributes.get("user");

        // 获取并执行退出编辑策略
        PictureEditMessageStrategy exitStrategy = strategyFactory.getStrategy(PictureEditMessageTypeEnum.EXIT_EDIT.getValue());
        exitStrategy.handle(null, session, user, pictureId);

        // 删除会话
        broadcaster.removeSession(pictureId, session);

        // 响应
        PictureEditResponseMessage pictureEditResponseMessage = new PictureEditResponseMessage();
        pictureEditResponseMessage.setType(PictureEditMessageTypeEnum.INFO.getValue());
        String message = String.format("%s离开编辑", user.getUserName());
        pictureEditResponseMessage.setMessage(message);
        pictureEditResponseMessage.setUser(userService.getUserVO(user));
        broadcaster.broadcastToPicture(pictureId, pictureEditResponseMessage);
    }
}

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