Spring Data 最佳实践
时间:2022-05-03
本文章向大家介绍Spring Data 最佳实践，主要内容包括第 12 章 Spring Data 最佳实践、12.1. 分类表、12.2. 为字段增加索引、12.3. 复合索引、12.4. 一对多实例、12.5. ManyToMany 多对多、基本概念、基础应用、原理机制和需要注意的事项等，并结合实例形式分析了其使用技巧，希望通过本文能帮助到大家理解应用这部分内容。
摘要: ORM的出现解决了程序猿学习数据库学历成本，也加快了开发的速度。程序猿无需再学习数据库定义语言DDL以及数据库客户端，也无需关注建表这些繁琐的工作，同时也降低了数据库结构变更管理中与DBA频繁沟通的成本。
本文节选自电子书《Netkiller Architect 手札》
第 12 章 Spring Data 最佳实践
目录
12.1. 分类表
12.2. 为字段增加索引
12.3. 复合索引
12.4. 一对多实例
12.5. ManyToMany 多对多
12.6. 外键级联删除
ORM的出现解决了程序猿学习数据库学历成本，也加快了开发的速度。程序猿无需再学习数据库定义语言DDL以及数据库客户端，也无需关注建表这些繁琐的工作，同时也降低了数据库结构变更管理中与DBA频繁沟通的成本。。
在过去的两年中我们采用 Spring Data JPA 定义数据库，访问数据库，积累了很多经验，最终我们发现使用 Spring Data 实体定义完全可以代替 DBA 的建模工作。
下面我们采用案例，一个一个讲解，各种数据库实体关系的定义。相关数据库建模知识请先阅读 《Netkiller Architect 手札》 以及 《Netkiller Spring 手札》
12.1. 分类表
这是一个通用分类表，常见的父子关系加上path路径
+-----------+ | category |
|-----------|
|id | <---+ |name | |
|description| 1:n
|status | |
|pid | o---+ |path |
|status |
|ctime |
|mtime |
+-----------+package cn.netkiller.domain;import java.util.Date;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;@Entitypublic class Category { @Id
@GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false) public int id; public String name; public String description; public String path; @Column(columnDefinition = "enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '状态'") public String status; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间'") public Date ctime; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更改时间'") public Date mtime; @ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) @JoinColumn(name = "pid", referencedColumnName = "id") private Category categorys; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "category", fetch = FetchType.EAGER) private Set<Category> category; public int getId() { return id;
} public void setId(int id) { this.id = id;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public String getDescription() { return description;
} public void setDescription(String description) { this.description = description;
} public String getPath() { return path;
} public void setPath(String path) { this.path = path;
} public String getStatus() { return status;
} public void setStatus(String status) { this.status = status;
} public Date getCtime() { return ctime;
} public void setCtime(Date ctime) { this.ctime = ctime;
} public Date getMtime() { return mtime;
} public void setMtime(Date mtime) { this.mtime = mtime;
} public Category getCategorys() { return categorys;
} public void setCategorys(Category categorys) { this.categorys = categorys;
} public Set<Category> getCategory() { return category;
} public void setCategory(Set<Category> category) { this.category = category;
} @Override
public String toString() { return "Category [id=" + id + ", name=" + name + ", description=" + description + ", path=" + path + ", status="
+ status + ", ctime=" + ctime + ", mtime=" + mtime + ", categorys=" + categorys + ", category="
+ category + "]";
}
}期望结果
CREATE TABLE `category` ( `id` int(11) NOT NULL AUTO_INCREMENT, `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '', `description` varchar(255) DEFAULT NULL, `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '', `name` varchar(255) DEFAULT NULL, `path` varchar(255) DEFAULT NULL, `status` enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '', `pid` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf812.2. 为字段增加索引
我们希望为 name 和 path 字段增加普通索引
package netkiller.domain;import java.util.Date;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Index;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import javax.persistence.Table;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;@Entity@Table(indexes = { @Index(name = "name", columnList = "name DESC"), @Index(name = "path", columnList = "path") })public class Category { @Id
@GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false) public int id; public String name; public String description; public String path; @Column(columnDefinition = "enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '状态'") public String status; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间'") public Date ctime; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更改时间'") public Date mtime; @ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) @JoinColumn(name = "pid", referencedColumnName = "id") private Category categorys; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "category", fetch = FetchType.EAGER) private Set<Category> category; public int getId() { return id;
} public void setId(int id) { this.id = id;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public String getDescription() { return description;
} public void setDescription(String description) { this.description = description;
} public String getPath() { return path;
} public void setPath(String path) { this.path = path;
} public String getStatus() { return status;
} public void setStatus(String status) { this.status = status;
} public Date getCtime() { return ctime;
} public void setCtime(Date ctime) { this.ctime = ctime;
} public Date getMtime() { return mtime;
} public void setMtime(Date mtime) { this.mtime = mtime;
} public Category getCategorys() { return categorys;
} public void setCategorys(Category categorys) { this.categorys = categorys;
} public Set<Category> getCategory() { return category;
} public void setCategory(Set<Category> category) { this.category = category;
} @Override
public String toString() { return "Category [id=" + id + ", name=" + name + ", description=" + description + ", path=" + path + ", status="
+ status + ", ctime=" + ctime + ", mtime=" + mtime + ", categorys=" + categorys + ", category="
+ category + "]";
}
}期望结果
CREATE TABLE `category` ( `id` int(11) NOT NULL AUTO_INCREMENT, `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '????', `description` varchar(255) DEFAULT NULL, `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '????', `name` varchar(255) DEFAULT NULL, `path` varchar(255) DEFAULT NULL, `status` enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '??', `pid` int(11) DEFAULT NULL,
PRIMARY KEY (`id`), KEY `name` (`name`), KEY `path` (`path`), KEY `FKeiel7nqjxu4kmefso9tm9qcsu` (`pid`), CONSTRAINT `FKeiel7nqjxu4kmefso9tm9qcsu` FOREIGN KEY (`pid`) REFERENCES `category` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf812.3. 复合索引
创建由多个字段组成的复合索引，如： "member_id", "articleId"
package cn.netkiller.api.model;import java.io.Serializable;import java.util.Date;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.Table;import javax.persistence.Temporal;import javax.persistence.TemporalType;import javax.persistence.UniqueConstraint;import com.fasterxml.jackson.annotation.JsonFormat;@Entity@Table(name = "comment", uniqueConstraints = { @UniqueConstraint(columnNames = { "member_id", "articleId" }) })public class Comment implements Serializable { /**
*
*/
private static final long serialVersionUID = -1484408775034277681L; @Id
@GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false) private int id; @ManyToOne(cascade = { CascadeType.ALL }) @JoinColumn(name = "member_id") private Member member; private int articleId; private String message; @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss") @Temporal(TemporalType.TIMESTAMP) @Column(updatable = false) @org.hibernate.annotations.CreationTimestamp protected Date createDate; public int getId() { return id;
} public void setId(int id) { this.id = id;
} public Member getMember() { return member;
} public void setMember(Member member) { this.member = member;
} public int getArticleId() { return articleId;
} public void setArticleId(int articleId) { this.articleId = articleId;
} public String getMessage() { return message;
} public void setMessage(String message) { this.message = message;
} public Date getCreateDate() { return createDate;
} public void setCreateDate(Date createDate) { this.createDate = createDate;
}
}期望结果
CREATE TABLE `comment` ( `id` int(11) NOT NULL AUTO_INCREMENT, `article_id` int(11) NOT NULL, `create_date` datetime DEFAULT NULL, `message` varchar(255) DEFAULT NULL, `member_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`), UNIQUE KEY `UK5qxfiu92nwlvgli7bl3evl11m` (`member_id`,`article_id`), CONSTRAINT `FKmrrrpi513ssu63i2783jyiv9m` FOREIGN KEY (`member_id`) REFERENCES `member` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;12.4. 一对多实例
如下图，我们将实现 categroy 和 article 的一对多关系
+-----------+ | category |
|-----------|
+-->|id | <---+ | |title | |
| |description| 1:n
| |status | |
| |parent_id | o---+ | +-----------+
|
1:n
|
| +-----------------+ +-----------------+ | | article | | feedback |
| |-----------------| |-----------------|
| |id |<--1:n--+ |id |
| |title | | |title |
| |content | | |content |
| |datetime | | |datetime |
| |status | | |status |
+--o|category_id | +--o|article_id |
+--o|member_id | +-->|member_id |
| +-----------------+ | +-----------------+
| | 2007,2008,2009 | | | 2007,2008,2009 |
| +-----------------+ | +-----------------+
| |
1:n +----------+ +---1:n---+
| | member | |
| |----------| |
+-->|id | <---+
|user |
|passwd |
|nickname |
|status |
+----------+首先定义分类实体类
package cn.netkiller.domain;import java.util.Date;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Index;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import javax.persistence.Table;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;@Entity@Table(indexes = { @Index(name = "name", columnList = "name DESC"), @Index(name = "path", columnList = "path") })public class Category { @Id
@GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false) public int id; public String name; public String description; public String path; @Column(columnDefinition = "enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '状态'") public String status; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间'") public Date ctime; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更改时间'") public Date mtime; @ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) @JoinColumn(name = "pid", referencedColumnName = "id") private Category categorys; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "category", fetch = FetchType.EAGER) private Set<Category> category; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "category", orphanRemoval = true) private Set<Article> article; public int getId() { return id;
} public void setId(int id) { this.id = id;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public String getDescription() { return description;
} public void setDescription(String description) { this.description = description;
} public String getPath() { return path;
} public void setPath(String path) { this.path = path;
} public String getStatus() { return status;
} public void setStatus(String status) { this.status = status;
} public Date getCtime() { return ctime;
} public void setCtime(Date ctime) { this.ctime = ctime;
} public Date getMtime() { return mtime;
} public void setMtime(Date mtime) { this.mtime = mtime;
} public Category getCategorys() { return categorys;
} public void setCategorys(Category categorys) { this.categorys = categorys;
} public Set<Category> getCategory() { return category;
} public void setCategory(Set<Category> category) { this.category = category;
} @Override
public String toString() { return "Category [id=" + id + ", name=" + name + ", description=" + description + ", path=" + path + ", status="
+ status + ", ctime=" + ctime + ", mtime=" + mtime + ", categorys=" + categorys + ", category="
+ category + "]";
}
}定义文章实体类
package cn.netkiller.domain;import java.io.Serializable;import java.util.Date;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import javax.persistence.Table;import org.springframework.format.annotation.DateTimeFormat;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;@Entity@Table(name = "article")public class Article implements Serializable { private static final long serialVersionUID = 7603772682950271321L; @Id
@GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false) public int id; public String title; @Column(name = "short") public String shortTitle; public String description; public String author; public int star; public String tag; public boolean share; public boolean status; public String content; @ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) @JoinColumn(name = "category_id", referencedColumnName = "id") private Category category; @ManyToOne(cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) @JoinColumn(name = "site_id", referencedColumnName = "id") private Site site; @ManyToOne(cascade = { CascadeType.ALL }) @JoinColumn(name = "member_id", referencedColumnName = "id") private Member member; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间'") public Date ctime; @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss") @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") @Column(columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更改时间'") public Date mtime; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "article", fetch = FetchType.EAGER) private Set<Comment> comment; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "article", fetch = FetchType.EAGER) private Set<Favorites> favorites; @JsonIgnore
@OneToMany(cascade = CascadeType.ALL, mappedBy = "article", orphanRemoval = true) private Set<Statistics> statistics; 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 getDescription() { return description;
} public void setDescription(String description) { this.description = description;
} public Date getCtime() { return ctime;
} public void setCtime(Date ctime) { this.ctime = ctime;
} public String getShortTitle() { return shortTitle;
} public void setShortTitle(String shortTitle) { this.shortTitle = shortTitle;
} public String getAuthor() { return author;
} public void setAuthor(String author) { this.author = author;
} public int getStar() { return star;
} public void setStar(int star) { this.star = star;
} public String getTag() { return tag;
} public void setTag(String tag) { this.tag = tag;
} public boolean isShare() { return share;
} public void setShare(boolean share) { this.share = share;
} public boolean isStatus() { return status;
} public void setStatus(boolean status) { this.status = status;
} public String getContent() { return content;
} public void setContent(String content) { this.content = content;
} public Category getCategory() { return category;
} public void setCategory(Category category) { this.category = category;
} public Member getMember() { return member;
} public void setMember(Member member) { this.member = member;
} public Set<Comment> getComment() { return comment;
} public void setComment(Set<Comment> comment) { this.comment = comment;
} public Set<Favorites> getFavorites() { return favorites;
} public void setFavorites(Set<Favorites> favorites) { this.favorites = favorites;
} public Set<Statistics> getStatistics() { return statistics;
} public void setStatistics(Set<Statistics> statistics) { this.statistics = statistics;
} public Site getSite() { return site;
} public void setSite(Site site) { this.site = site;
} public Date getMtime() { return mtime;
} public void setMtime(Date mtime) { this.mtime = mtime;
} @Override
public String toString() { return "Article [id=" + id + ", title=" + title + ", shortTitle=" + shortTitle + ", description=" + description
+ ", author=" + author + ", star=" + star + ", tag=" + tag + ", share=" + share + ", status=" + status
+ ", content=" + content + ", category=" + category + ", site=" + site + ", member=" + member
+ ", ctime=" + ctime + ", mtime=" + mtime + ", comment=" + comment + ", favorites=" + favorites
+ ", statistics=" + statistics + "]";
}
}希望结果
CREATE TABLE `category` ( `id` int(11) NOT NULL AUTO_INCREMENT, `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '????', `description` varchar(255) DEFAULT NULL, `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '????', `name` varchar(255) DEFAULT NULL, `path` varchar(255) DEFAULT NULL, `status` enum('Enabled','Disabled') DEFAULT 'Enabled' COMMENT '??', `pid` int(11) DEFAULT NULL,
PRIMARY KEY (`id`), KEY `name` (`name`), KEY `path` (`path`), KEY `FKeiel7nqjxu4kmefso9tm9qcsu` (`pid`), CONSTRAINT `FKeiel7nqjxu4kmefso9tm9qcsu` FOREIGN KEY (`pid`) REFERENCES `category` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;CREATE TABLE `article` ( `id` int(11) NOT NULL AUTO_INCREMENT, `author` varchar(255) DEFAULT NULL, `content` varchar(255) DEFAULT NULL, `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '????', `description` varchar(255) DEFAULT NULL, `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '????', `share` bit(1) NOT NULL, `short` varchar(255) DEFAULT NULL, `star` int(11) NOT NULL, `status` bit(1) NOT NULL, `tag` varchar(255) DEFAULT NULL, `title` varchar(255) DEFAULT NULL, `category_id` int(11) DEFAULT NULL, `member_id` int(11) DEFAULT NULL, `site_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`), KEY `FKy5kkohbk00g0w88fi05k2hcw` (`category_id`), KEY `FK6l9vkfd5ixw8o8kph5rj1k7gu` (`member_id`), KEY `FKrxbc33rok9m4n6pnbbwb3piwf` (`site_id`), CONSTRAINT `FK6l9vkfd5ixw8o8kph5rj1k7gu` FOREIGN KEY (`member_id`) REFERENCES `member` (`id`), CONSTRAINT `FKrxbc33rok9m4n6pnbbwb3piwf` FOREIGN KEY (`site_id`) REFERENCES `site` (`id`), CONSTRAINT `FKy5kkohbk00g0w88fi05k2hcw` FOREIGN KEY (`category_id`) REFERENCES `category` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;现在我们已经将 categroy 与 article 两张表一对多关系建立起来。
12.5. ManyToMany 多对多
用户与角色就是一个多对多的关系，多对多是需要中间表做关联的。所以需要一个 user_has_role 表。
+----------+ +---------------+ +--------+ | users | | user_has_role | | role |
+----------+ +---------------+ +--------+ | id | <------o | user_id | /---> | id |
| name | | role_id | o---+ | name |
| password | | | | |
+----------+ +---------------+ +--------+创建 User 表
package cn.netkiller.api.domain.test;import java.io.Serializable;import java.util.Set;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinTable;import javax.persistence.ManyToMany;import javax.persistence.Table;import javax.persistence.JoinColumn;@Entity@Table(name = "users")public class Users implements Serializable { /**
*
*/
private static final long serialVersionUID = -2480194112597046349L; @Id
@GeneratedValue(strategy = GenerationType.AUTO) private int id; private String name; private String password; @ManyToMany(fetch = FetchType.EAGER) @JoinTable(name = "user_has_role", joinColumns = { @JoinColumn(name = "user_id", referencedColumnName = "id") }, inverseJoinColumns = { @JoinColumn(name = "role_id", referencedColumnName = "id") }) private Set<Roles> roles; public int getId() { return id;
} public void setId(int id) { this.id = id;
} 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 Set<Roles> getRoles() { return roles;
} public void setRoles(Set<Roles> roles) { this.roles = roles;
} @Override
public String toString() { return "Users [id=" + id + ", name=" + name + ", password=" + password + ", roles=" + roles + "]";
}
}创建 Role 表
package cn.netkiller.api.domain.test;import java.io.Serializable;import java.util.Set;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.ManyToMany;import javax.persistence.Table;@Entity@Table(name = "roles")public class Roles implements Serializable { private static final long serialVersionUID = 6737037465677800326L; @Id
@GeneratedValue(strategy = GenerationType.AUTO) private int id; private String name; @ManyToMany(mappedBy = "roles") private Set<Users> users; public int getId() { return id;
} public void setId(int id) { this.id = id;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public Set<Users> getUsers() { return users;
} public void setUsers(Set<Users> users) { this.users = users;
} @Override
public String toString() { return "Roles [id=" + id + ", name=" + name + ", users=" + users + "]";
}
}最终产生数据库表如下
CREATE TABLE `users` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(255) NULL DEFAULT NULL, `password` VARCHAR(255) NULL DEFAULT NULL,
PRIMARY KEY (`id`)
)COLLATE='utf8_general_ci'ENGINE=InnoDB;
CREATE TABLE `roles` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `name` VARCHAR(255) NULL DEFAULT NULL,
PRIMARY KEY (`id`)
)COLLATE='utf8_general_ci'ENGINE=InnoDB;
CREATE TABLE `user_has_role` ( `user_id` INT(11) NOT NULL, `role_id` INT(11) NOT NULL,
PRIMARY KEY (`user_id`, `role_id`), INDEX `FKsvvq61v3koh04fycopbjx72hj` (`role_id`), CONSTRAINT `FK2dl1ftxlkldulcp934i3125qo` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`), CONSTRAINT `FKsvvq61v3koh04fycopbjx72hj` FOREIGN KEY (`role_id`) REFERENCES `roles` (`id`)
)COLLATE='utf8_general_ci'ENGINE=InnoDB;
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