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四. DAO层和model

四. DAO层和model

作者: stoneyang94 | 来源:发表于2018-08-14 19:29 被阅读0次
结构

5. DAO

DAO

5.1 CommentDAO

@Mapper
public interface CommentDAO {
    String TABLE_NAME = " comment ";
    String INSERT_FIELDS = " user_id, content, created_date, entity_id, entity_type, status ";
    String SELECT_FIELDS = " id, " + INSERT_FIELDS;

    @Insert({"insert into ", TABLE_NAME, "(", INSERT_FIELDS,
            ") values (#{userId},#{content},#{createdDate},#{entityId},#{entityType},#{status})"})
    int addComment(Comment comment);

    @Update({"update ", TABLE_NAME, " set status=#{status} where entity_id=#{entityId} and entity_type=#{entityType}"})
    void updateStatus(@Param("entityId") int entityId, @Param("entityType") int entityType, @Param("status") int status);

    @Select({"select ", SELECT_FIELDS, " from ", TABLE_NAME,
            " where entity_id=#{entityId} and entity_type=#{entityType} order by id desc"})
    List<Comment> selectByEntity(@Param("entityId") int entityId, @Param("entityType") int entityType);

    @Select({"select count(id) from ", TABLE_NAME, " where entity_id=#{entityId} and entity_type=#{entityType} "})
    int getCommentCount(@Param("entityId") int entityId, @Param("entityType") int entityType);
}

1)DAO在JavaWeb开发中的定位

DAO在JavaWeb开发中的定位

一个典型的DAO实现有下列几个组件：
1.一个DAO接口(CRUD)
2.一个实现DAO接口的具体类
3.数据传递对象(DTO)(POJO)：有些时候叫做值对象(VO)或领域模型（domain）

2)@Mapper注解

mybatis对java自定义注解的使用——入门篇

作用：持久化

  • 一种持久化方式：
    在一个包中写一个DAO的接口，在另一个包里面写DAO的实现，使用sqlMapClient来从***-sql.xml中读取相应的sql。
  • spring+Mybatis的项目，一种新的持久化方式：
    只写一个dao的接口，在接口的方法中直接注解上用到的sql语句，接口上方多了一个@Mapper注解。

3）@Param

@Param注解

mybatis中使用@param和不使用区别

1，使用@Param注解

当以下面的方式进行写SQL语句时：

    @Select("select column from table where userid = #{userid} ")
    public int selectColumn(int userid);

当你使用了使用@Param注解来声明参数时，如果使用 #{} 或 ${} 的方式都可以。

    @Select("select column from table where userid = ${userid} ")
    public int selectColumn(@Param("userid") int userid);

当你不使用@Param注解来声明参数时，必须使用使用 #{}方式。如果使用 ${} 的方式，会报错。

    @Select("select column from table where userid = ${userid} ")
    public int selectColumn(@Param("userid") int userid);

2，不使用@Param注解

不使用@Param注解时，参数只能有一个，并且是Javabean。在SQL语句里可以引用JavaBean的属性，而且只能引用JavaBean的属性。

// 这里id是user的属性

@Select("SELECT * from Table where id = ${id}")
Enchashment selectUserById(User user);

5.2 LoginTicketDAO

@Mapper
public interface LoginTicketDAO {
    String TABLE_NAME = "login_ticket";
    String INSERT_FIELDS = " user_id, expired, status, ticket ";
    String SELECT_FIELDS = " id, " + INSERT_FIELDS;

    @Insert({"insert into ", TABLE_NAME, "(", INSERT_FIELDS,
            ") values (#{userId},#{expired},#{status},#{ticket})"})
    int addTicket(LoginTicket ticket);

    @Select({"select ", SELECT_FIELDS, " from ", TABLE_NAME, " where ticket=#{ticket}"})
    LoginTicket selectByTicket(String ticket);

    @Update({"update ", TABLE_NAME, " set status=#{status} where ticket=#{ticket}"})
    void updateStatus(@Param("ticket") String ticket, @Param("status") int status);
}

5.3 MessageDAO

@Mapper
public interface MessageDAO {
    String TABLE_NAME = " message ";
    String INSERT_FIELDS = " from_id, to_id, content, has_read, conversation_id, created_date ";
    String SELECT_FIELDS = " id, " + INSERT_FIELDS;

    @Insert({"insert into ", TABLE_NAME, "(", INSERT_FIELDS,
            ") values (#{fromId},#{toId},#{content},#{hasRead},#{conversationId},#{createdDate})"})
    int addMessage(Message message);

    @Select({"select ", SELECT_FIELDS, " from ", TABLE_NAME, " where conversation_id=#{conversationId} order by id desc limit #{offset}, #{limit}"})
    List<Message> getConversationDetail(@Param("conversationId") String conversationId,
                                        @Param("offset") int offset, @Param("limit") int limit);

    @Select({"select count(id) from ", TABLE_NAME, " where has_read=0 and to_id=#{userId} and conversation_id=#{conversationId}"})
    int getConvesationUnreadCount(@Param("userId") int userId, @Param("conversationId") String conversationId);

    @Select({"select ", INSERT_FIELDS, " ,count(id) as id from ( select * from ", TABLE_NAME, " where from_id=#{userId} or to_id=#{userId} order by id desc) tt group by conversation_id  order by created_date desc limit #{offset}, #{limit}"})
    List<Message> getConversationList(@Param("userId") int userId,
                                      @Param("offset") int offset, @Param("limit") int limit);
}

5.4 NewsDAO

@Mapper
public interface NewsDAO {
    String TABLE_NAME = "news";
    String INSERT_FIELDS = " title, link, image, like_count, comment_count, created_date, user_id ";
    String SELECT_FIELDS = " id, " + INSERT_FIELDS;

    @Insert({"insert into ", TABLE_NAME, "(", INSERT_FIELDS,
            ") values (#{title},#{link},#{image},#{likeCount},#{commentCount},#{createdDate},#{userId})"})
    int addNews(News news);

    @Select({"select ", SELECT_FIELDS , " from ", TABLE_NAME, " where id=#{id}"})
    News getById(int id);

    @Update({"update ", TABLE_NAME, " set comment_count = #{commentCount} where id=#{id}"})
    int updateCommentCount(@Param("id") int id, @Param("commentCount") int commentCount);

    @Update({"update ", TABLE_NAME, " set like_count = #{likeCount} where id=#{id}"})
    int updateLikeCount(@Param("id") int id, @Param("likeCount") int likeCount);

    List<News> selectByUserIdAndOffset(@Param("userId") int userId, @Param("offset") int offset,
                                       @Param("limit") int limit);
}

int addNews(News news); 发布资讯

News selectById(int id); 点击详情页时根据newsId查询资讯

int updateCommentCount(@Param("id") int id, @Param("commentCount") int commentCount); 资讯详情页时改评论数量

List<News> selectByUserIdAndOffset(@Param("userId") int userId, @Param("offset") int offset, @Param("limit") int limit); 点击具体用户头像可查询该用户发布的所有资讯。

5.5 UserDAO

@Mapper
public interface UserDAO {
    String TABLE_NAME = "user";
    String INSET_FIELDS = " name, password, salt, head_url ";
    String SELECT_FIELDS = " id, name, password, salt, head_url";

    @Insert({"insert into ", TABLE_NAME, "(", INSET_FIELDS,
            ") values (#{name},#{password},#{salt},#{headUrl})"})
    int addUser(User user);

    @Select({"select ", SELECT_FIELDS, " from ", TABLE_NAME, " where id=#{id}"})
    User selectById(int id);

    @Select({"select ", SELECT_FIELDS, " from ", TABLE_NAME, " where name=#{name}"})
    User selectByName(String name);

    @Update({"update ", TABLE_NAME, " set password=#{password} where id=#{id}"})
    void updatePassword(User user);

    @Delete({"delete from ", TABLE_NAME, " where id=#{id}"})
    void deleteById(int id);
}

7. model

model

7.1 Comment

通过entityId（如对news进行评论entityId就是newsId ）和entityType的实时变化组合，可以代表对不同的东西进行评论。

public class Comment {
    private int id;
    private int userId;
    private int entityId;
    private int entityType;
    private String content;
    private Date createdDate;
    private int status;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public int getEntityId() {
        return entityId;
    }

    public void setEntityId(int entityId) {
        this.entityId = entityId;
    }

    public int getEntityType() {
        return entityType;
    }

    public void setEntityType(int entityType) {
        this.entityType = entityType;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Date getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(Date createdDate) {
        this.createdDate = createdDate;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }
}

7.2 EntityType

public class EntityType {
    public static int ENTITY_NEWS = 1;
    public static int ENTITY_COMMENT = 2;
}

7.3 HostHolder

结合PassportInterceptor
用来持有用户，表示当前的用户是谁。

@Component
public class HostHolder {
//多线程访问的，要注意多线程安全
    private static ThreadLocal<User> users = new ThreadLocal<User>();

    public User getUser() {
        return users.get();
    }
    public void setUser(User user) {
        users.set(user);
    }

    public void clear() {
        users.remove();
    }
}

7.4 LoginTicket

public class LoginTicket {
    private int id;
    private int userId;
    private Date expired;
    private int status;// 0有效，1无效
    private String ticket;

    public String getTicket() {
        return ticket;
    }
    public void setTicket(String ticket) {
        this.ticket = ticket;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }

    public int getUserId() {
        return userId;
    }
    public void setUserId(int userId) {
        this.userId = userId;
    }

    public Date getExpired() {
        return expired;
    }
    public void setExpired(Date expired) {
        this.expired = expired;
    }

    public int getStatus() {
        return status;
    }
    public void setStatus(int status) {
        this.status = status;
    }
}

7.5 Message

public class Message {
    private int id;
    private int fromId;
    private int toId;
    private String content;
    private Date createdDate;
    private int hasRead;
    private String conversationId;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getFromId() {
        return fromId;
    }

    public void setFromId(int fromId) {
        this.fromId = fromId;
    }

    public int getToId() {
        return toId;
    }

    public void setToId(int toId) {
        this.toId = toId;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Date getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(Date createdDate) {
        this.createdDate = createdDate;
    }

    public int getHasRead() {
        return hasRead;
    }

    public void setHasRead(int hasRead) {
        this.hasRead = hasRead;
    }

    public String getConversationId() {
        if (fromId < toId) {
            return String.format("%d_%d", fromId, toId);
        }
        return String.format("%d_%d", toId, fromId);
    }
}

7.6 News

public class News {
  private int id;
  private String title;
  private String link;
  private String image;
  private int likeCount;
  private int commentCount;
  private Date createdDate;
  private int userId;

  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }

  public String getTitle() {
    return title;
  }
  public void setTitle(String title) {
    this.title = title;
  }

  public String getLink() {
    return link;
  }
  public void setLink(String link) {
    this.link = link;
  }

  public String getImage() {
    return image;
  }
  public void setImage(String image) {
    this.image = image;
  }

  public int getLikeCount() {
    return likeCount;
  }
  public void setLikeCount(int likeCount) {
    this.likeCount = likeCount;
  }

  public int getCommentCount() {
    return commentCount;
  }
  public void setCommentCount(int commentCount) {
    this.commentCount = commentCount;
  }

  public Date getCreatedDate() {
    return createdDate;
  }
  public void setCreatedDate(Date createdDate) {
    this.createdDate = createdDate;
  }

  public int getUserId() {
    return userId;
  }
  public void setUserId(int userId) {
    this.userId = userId;
  }
}

7.7 User

public class User {
    private int id;
    private String name;
    private String password;
    private String salt;
    private String headUrl;

    public User() {
    }
    public User(String name) {
        this.name = name;
        this.password = "";
        this.salt = "";
        this.headUrl = "";
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    public String getSalt() {
        return salt;
    }
    public void setSalt(String salt) {
        this.salt = salt;
    }

    public String getHeadUrl() {
        return headUrl;
    }
    public void setHeadUrl(String headUrl) {
        this.headUrl = headUrl;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
}

7.8 ViewObject

public class ViewObject {
    private Map<String, Object> objs = new HashMap<String, Object>();
    public void set(String key, Object value) {
        objs.put(key, value);
    }

    public Object get(String key) {
        return objs.get(key);
    }
}

sql

数据库 
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(64) NOT NULL DEFAULT '',
  `password` varchar(128) NOT NULL DEFAULT '',
  `salt` varchar(32) NOT NULL DEFAULT '',
  `head_url` varchar(256) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `news`;
CREATE TABLE `news` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `title` varchar(128) NOT NULL DEFAULT '',
  `link` varchar(256) NOT NULL DEFAULT '',
  `image` varchar(256) NOT NULL DEFAULT '',
  `like_count` int NOT NULL,
  `comment_count` int NOT NULL,
  `created_date` datetime NOT NULL,
  `user_id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `login_ticket`;
CREATE TABLE `login_ticket` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `user_id` INT NOT NULL,
  `ticket` VARCHAR(45) NOT NULL,
  `expired` DATETIME NOT NULL,
  `status` INT NULL DEFAULT 0,
  PRIMARY KEY (`id`),
  UNIQUE INDEX `ticket_UNIQUE` (`ticket` ASC)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `comment`;
CREATE TABLE `comment` (
`id` INT NOT NULL AUTO_INCREMENT,
`content` TEXT NOT NULL,
`user_id` INT NOT NULL,
`entity_id` INT NOT NULL,
`entity_type` INT NOT NULL,
`created_date` DATETIME NOT NULL,
`status` INT NOT NULL DEFAULT 0,
PRIMARY KEY (`id`),
INDEX `entity_index` (`entity_id` ASC, `entity_type` ASC)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `message`;
CREATE TABLE `message` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `from_id` INT NULL,
  `to_id` INT NULL,
  `content` TEXT NULL,
  `created_date` DATETIME NULL,
  `has_read` INT NULL,
  `conversation_id` VARCHAR(45) NOT NULL,
  PRIMARY KEY (`id`),
  INDEX `conversation_index` (`conversation_id` ASC),
  INDEX `created_date` (`created_date` ASC))
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;

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