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5.3. Spring Data JPA

5.3.1. @Entity

5.3.1.1. @Id

ID 字段

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false)
	private int id;
			

5.3.1.2. @Table

配置Schema

			
@Table(name="tabname", schema="public")
			
			

5.3.1.3. @Column

unique		属性表示该字段是否为唯一标识,默认为false。如果表中有一个字段需要唯一标识,则既可以使用该标记,也可以使用@Table标记中的@UniqueConstraint。
nullable		属性表示该字段是否可以为null值,默认为true。
insertable	属性表示在使用“INSERT”脚本插入数据时,是否需要插入该字段的值。
updatable	属性表示在使用“UPDATE”脚本插入数据时,是否需要更新该字段的值。insertable和updatable属性一般多用于只读的属性,例如主键和外键等。这些字段的值通常是自动生成的。
columnDefinition属性表示创建表时,该字段创建的SQL语句,一般用于通过Entity生成表定义时使用。
table		属性表示当映射多个表时,指定表的表中的字段。默认值为主表的表名。
length		属性表示字段的长度,当字段的类型为varchar时,该属性才有效,默认为255个字符。
precision	属性和scale属性表示精度,当字段类型为double时,precision表示数值的总长度,scale表示小数点所占的位数。
			
5.3.1.3.1. 字段长度

字段长度定义

				
@Column(name="name", length=80, nullable=true)	
				
				
5.3.1.3.2. 浮点型
				
	@Column(precision=18, scale=5)  
    private BigDecimal principal; 	
    
    @Column(name="Price", columnDefinition="Decimal(10,2) default '100.00'")			
				
				
5.3.1.3.3. 创建于更新控制
@Column(name = "ctime", nullable = false, insertable = false, updatable = false)		
				

5.3.1.4. @NotNull 不能为空声明

@NotNull
public String username;
			

5.3.1.5. @DateTimeFormat 处理日期时间格式

public java.sql.Date createdate; 创建日期 YYYY-MM-DD 
public java.util.Date finisheddate; 创建日期时间 YYYY-MM-DD HH:MM:SS
			

Json默认为 yyyy-MM-ddTHH:mm:ss 注意日期与时间中间的T,修改日期格式将T去掉

@DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
			

5.3.1.6. 默认时间规则

5.3.1.6.1. CreatedDate

Spring 提供了 import org.springframework.data.annotation.CreatedDate;

但是这些只能作用于实体类。

				
	@CreatedDate
    private Date createdDateTime;			
				
				
5.3.1.6.2. 与时间日期有关的 hibernate 注解
5.3.1.6.2.1. 设置默认时间
				
@Column(insertable = false) 
@org.hibernate.annotations.ColumnDefault("1.00") 
@org.hibernate.annotations.Generated(
org.hibernate.annotations.GenerationTime.INSERT
) 
protected Date lastModified; 
				
				
5.3.1.6.2.2. 创建时间
				
@Temporal(TemporalType.TIMESTAMP)  
@Column(updatable = false)  
@org.hibernate.annotations.CreationTimestamp  
protected Date createdDate;   			
				
				
5.3.1.6.2.3. 更新时间
				
@Column(name="update_time")  
@org.hibernate.annotations.UpdateTimestamp  
@Temporal(TemporalType.TIMESTAMP)
private Date updateTime;    			
				
				
				
@Temporal(TemporalType.TIMESTAMP)  
@Column(insertable = false, updatable = false)  
@org.hibernate.annotations.Generated(  
org.hibernate.annotations.GenerationTime.ALWAYS  
) 
				
				
5.3.1.6.3. 数据库级别的默认创建日期时间定义
				
package cn.netkiller.api.domain.elasticsearch;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table
public class ElasticsearchTrash {
	@Id
	private int id;

	@Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
	private Date ctime;

	public int getId() {
		return id;
	}

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

	public Date getCtime() {
		return ctime;
	}

	public void setCtime(Date ctime) {
		this.ctime = ctime;
	}

}				
				
				

对应数据库DDL

				
CREATE TABLE `elasticsearch_trash` (
  `id` int(11) NOT NULL,
  `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
				
				
5.3.1.6.4. 数据库级别的默认创建日期与更新时间定义

需求是这样的:

1. 创建时间与更新时间只能由数据库产生,不允许在实体类中产生,因为每个节点的时间/时区不一定一直。另外防止人为插入自定义时间时间。

2. 插入记录的时候创建默认时间,创建时间不能为空,时间一旦插入不允许日后在实体类中修改。

3. 记录创建后更新日志字段为默认为 null 表示该记录没有被修改过。一旦数据被修改,修改日期字段将记录下最后的修改时间。

4. 甚至你可以通过触发器实现一个history 表,用来记录数据的历史修改,详细请参考作者另一部电子书《Netkiller Architect 手札》数据库设计相关章节。

				
package cn.netkiller.api.domain.elasticsearch;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.validation.constraints.Null;

@Entity
@Table
public class ElasticsearchTrash {
	@Id
	private int id;

	// 创建时间
	@Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
	private Date ctime;
	
	// 修改时间
	@Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
	private Date mtime;

	public int getId() {
		return id;
	}

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

	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;
	}

}		
				
				

对应数据库DDL

				
CREATE TABLE `elasticsearch_trash` (
  `id` int(11) NOT NULL,
  `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
				
				
5.3.1.6.5. 最后修改时间

需求:记录最后一次修改时间

				
package cn.netkiller.api.domain.elasticsearch;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table
public class ElasticsearchTrash {
	@Id
	private int id;

	@Column(columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP")
	private Date lastModified;

}					
				
				

产生DDL语句如下

				
CREATE TABLE `elasticsearch_trash` (
  `id` int(11) NOT NULL,
  `last_modified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;				
				
				

5.3.1.7. 索引

针对字段做唯一索引

@Column(unique = true)			
			

创建复合索引

			
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;
	}
}
			
			
			
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;
			
			

5.3.1.8. Enum 枚举数据类型

5.3.1.8.1. 实体中处理 enum 类型

@Enumerated(value = EnumType.ORDINAL) //ORDINAL序数

在实体中处理枚举类型适用于所有数据库,Spring data 将枚举视为 String 类型。

package cn.netkiller.api.domain;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "statistics_history")
public class StatisticsHistory implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false)
	private long id;
	private long memberId;
	private long statisticsId;

	public enum StatisticsType {
		LIKE, COMMENT, BROWSE;
	}

	private StatisticsType type;

	public Long getId() {
		return id;
	}

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

	public long getMemberId() {
		return memberId;
	}

	public void setMemberId(long memberId) {
		this.memberId = memberId;
	}

	public long getStatisticsId() {
		return statisticsId;
	}

	public void setStatisticsId(long statisticsId) {
		this.statisticsId = statisticsId;
	}

	public StatisticsType getType() {
		return type;
	}

	public void setType(StatisticsType type) {
		this.type = type;
	}

}
		
				

默认 enum 类型创建数据库等效 int(11)

				
CREATE TABLE `statistics_history` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `member_id` bigint(20) NOT NULL,
  `statistics_id` bigint(20) NOT NULL,
  `type` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
SELECT * FROM test.statistics;
				
				

@Enumerated(EnumType.STRING) 注解可以使其成功字符串类型。

	public enum StatisticsType {
		LIKE, COMMENT, BROWSE;
	}

	@Enumerated(EnumType.STRING)
	private StatisticsType type;
				

SQL

				
CREATE TABLE `statistics_history` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `member_id` bigint(20) NOT NULL,
  `statistics_id` bigint(20) NOT NULL,
  `type` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
				
				
5.3.1.8.2. 数据库枚举类型

在枚举中处理类型虽然可以适用于所有数据库,但有时我们希望适用数据库的枚举类型(例如MySQL),数据库中得枚举类型要比字符串效率更高

				
package cn.netkiller.api.domain.elasticsearch;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table
public class NetkillerTrash {
	@Id
	private int id;

	@Column(columnDefinition = "enum('Y','N') DEFAULT 'N'")
	private boolean status;

	public int getId() {
		return id;
	}

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

	public boolean isStatus() {
		return status;
	}

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

}				
				
				

实际对应的数据库DLL

				
CREATE TABLE `netkiller_trash` (
  `id` int(11) NOT NULL,
  `status` enum('Y','N') DEFAULT 'N',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
				
				

5.3.1.9. 整形数据类型

无符号整形

			
package com.example.api.domain.elasticsearch;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table
public class Member {
	@Id
	private int id;
		
	@Column(columnDefinition = "INT(10) UNSIGNED NOT NULL")
	private int age;
	
	@Column(insertable = false, updatable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
	private Date ctime;

	@Column(nullable = true, insertable = false, updatable = false, columnDefinition = "TIMESTAMP NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP")
	private Date mtime;

	@Column(columnDefinition = "enum('Y','N') DEFAULT 'N'")
	private boolean status;
}			
			
			
			
CREATE TABLE `member` (
  `id` int(11) NOT NULL,
  `age` int(10) unsigned NOT NULL,
  `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `mtime` timestamp NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
  `status` enum('Y','N') DEFAULT 'N',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8			
			
			

5.3.1.10. @JoinColumn

@JoinColumn与@Column注释类似,它的定义如下代码所示。

			
@Target({METHOD, FIELD}) @Retention(RUNTIME) 

public @interface JoinColumn { 

String name() default ""; 

String referencedColumnName() default ""; 

boolean unique() default false; 

boolean nullable() default true; 

boolean insertable() default true; 

boolean updatable() default true; 

String columnDefinition() default ""; 

String table() default ""; 

}
			
			

5.3.1.11. @OneToOne

一对一表结构,如下面ER图所示,users表是用户表里面有登陆信息,profile 保存的时死人信息,这样的目的是我们尽量减少users表的字段,在频繁操作该表的时候性能比较好,另外一个目的是为了横向水平扩展。

			
    +----------+             +------------+
    | users    |             | profile    |
    +----------+             +------------+
    | id       | <---1:1---o | id         |
    | name     |             | sex        |    
    | password |             | email      |    
    +----------+             +------------+ 
			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "users")
public class Users implements Serializable {
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;
	private String password;

	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;
	}

	@Override
	public String toString() {
		return "Users [id=" + id + ", name=" + name + ", password=" + password + "]";
	}
}

			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "profile")
public class Profile implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = -2500499458196257167L;
	@Id
	@OneToOne
	@JoinColumn(name = "id")
	private Users users;

	private int age;
	private String sex;
	private String email;

	public Users getUsers() {
		return users;
	}

	public void setUsers(Users users) {
		this.users = users;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	@Override
	public String toString() {
		return "Profile [users=" + users + ", age=" + age + ", sex=" + sex + ", email=" + email + "]";
	}

}

			
			
			
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 `profile` (
	`age` INT(11) NOT NULL,
	`email` VARCHAR(255) NULL DEFAULT NULL,
	`sex` VARCHAR(255) NULL DEFAULT NULL,
	`id` INT(11) NOT NULL,
	PRIMARY KEY (`id`),
	CONSTRAINT `FK6x079ilawxjrfsljwyyi5ujjq` FOREIGN KEY (`id`) REFERENCES `users` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;
			
			

如果第二张表关联的并非主表的PK(主键)需要使用 referencedColumnName 指定。

			
@JoinColumn(name = "member_id",referencedColumnName="member_id") 			
			
			

5.3.1.12. OneToMany 一对多

我们要实现一个一对多实体关系,ER 图如下

			
    +----------+          +------------+
    | Classes  |          | Student    |
    +----------+          +------------+
    | id       | <---+    | id         |
    | name     |     |    | name       |    
    +----------+     +--o | classes_id |    
                          +------------+ 
    
			
			

classes 表需要 OneToMany 注解,Student 表需要 ManyToOne 注解,这样就建立起了表与表之间的关系

			
package cn.netkiller.api.domain.test;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity 
@Table(name="classes") 
public class Classes implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = -5422905745519948312L;
	@Id 
	@GeneratedValue(strategy=GenerationType.AUTO) 
	private int id; 
	private String name; 
	    
	@OneToMany(cascade=CascadeType.ALL,mappedBy="classes")    
	private Set<Student> students;

	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<Student> getStudents() {
		return students;
	}

	public void setStudents(Set<Student> students) {
		this.students = students;
	}

	@Override
	public String toString() {
		return "classes [id=" + id + ", name=" + name + ", students=" + students + "]";
	} 
}
			
			
			
package cn.netkiller.api.domain.test;

import java.io.Serializable;

import javax.persistence.CascadeType;
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;

@Entity
@Table(name = "student")
public class Student implements Serializable{
	/**
	 * 
	 */
	private static final long serialVersionUID = 6737037465677800326L;
	@Id
	@GeneratedValue(strategy = GenerationType.AUTO)
	private int id;
	private String name;

	// 若有多个cascade,可以是:{CascadeType.PERSIST,CascadeType.MERGE}
	@ManyToOne(cascade = { CascadeType.ALL })
	@JoinColumn(name = "classes_id") 
	private Classes classes;

	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 Classes getClasses() {
		return classes;
	}

	public void setClasses(Classes classes) {
		this.classes = classes;
	}

	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", classes=" + classes + "]";
	}

}

			
			

最终 SQL 表如下

			
CREATE TABLE `classes` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;	
			
CREATE TABLE `student` (
	`id` INT(11) NOT NULL AUTO_INCREMENT,
	`name` VARCHAR(255) NULL DEFAULT NULL,
	`class_id` INT(11) NULL DEFAULT NULL,
	PRIMARY KEY (`id`),
	INDEX `FKnsl7w2nw6o6eq53hqlxfcijpm` (`class_id`),
	CONSTRAINT `FKnsl7w2nw6o6eq53hqlxfcijpm` FOREIGN KEY (`class_id`) REFERENCES `classes` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;
			
			
			
      Classes classes=new Classes(); 
      classes.setName("One"); 
        
      Student st1=new Student(); 
      st1.setSname("jason"); 
      st1.setClasses(classes); 
      studentRepostitory.save(st1); 
        
      Student st2=new Student(); 
      st2.setSname("neo"); 
      st2.setClasses(classes); 
      studentRepostitory.save(st2); 
			
			

5.3.1.13. 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。所以我方需要一个 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;
			
			
			
			
			

5.3.1.14. 外键级联删除

orphanRemoval = true 可以实现数据级联删除

			
package cn.netkiller.api.domain;

import java.io.Serializable;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Table;

import com.fasterxml.jackson.annotation.JsonIgnore;

@Entity
@Table(name = "member")
public class Member implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false)
	private int id;

	private String name;
	private String sex;
	private int age;
	private String wechat;

	@Column(unique = true)
	private String mobile;
	private String picture;
	private String ipAddress;

	@JsonIgnore
	@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "member")
	private Set<Comment> comment;
	@JsonIgnore
	@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "member")
	private Set<StatisticsHistory> statisticsHistory;

	public Member() {
	}

	public Member(int id) {
		this.id = id;
	}

	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 getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public String getWechat() {
		return wechat;
	}

	public void setWechat(String wechat) {
		this.wechat = wechat;
	}

	public String getMobile() {
		return mobile;
	}

	public void setMobile(String mobile) {
		this.mobile = mobile;
	}

	public String getPicture() {
		return picture;
	}

	public void setPicture(String picture) {
		this.picture = picture;
	}

	public String getIpAddress() {
		return ipAddress;
	}

	public void setIpAddress(String ipAddress) {
		this.ipAddress = ipAddress;
	}

	@Override
	public String toString() {
		return "Member [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + ", wechat=" + wechat + ", mobile=" + mobile + ", picture=" + picture + ", ipAddress=" + ipAddress + "]";
	}

}
			
			
			

5.3.1.15. 其他

5.3.1.15.1. Cascade
CascadeType.PERSIST (级联新建) 
CascadeType.REMOVE  (级联删除) 
CascadeType.REFRESH (级联刷新) 
CascadeType.MERGE   (级联更新)中选择一个或多个。 
CascadeType.ALL			
				
5.3.1.15.2. @JsonIgnore

当尸体返回 Json 数据结构是,将不包含 @JsonIgnore 定义变量。

				
	@JsonIgnore  
    @OneToMany(mappedBy = "owner")  
    private List<Pet> pets;  
				
				

5.3.2. 实体集成

B、C 类继承 A 所有属性,并且主键均为数据库(auto_increment)

		
@MappedSuperclass
@(strategy = InheritanceType.TABLE_PER_CLASS)
public class A{
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
}
		
		
		
@Entity
@Table(name="b")
public class B extends A{

}
		
		
		
@Entity
@Table(name="c")
public class C extends A{

}		
		
		

5.3.3. Repository

Spring Data JPA 为此提供了一些表达条件查询的关键字:

		
Keyword	Sample	JPQL snippet
And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstnameIs,findByFirstnameEquals	… where x.firstname = ?1
Between	findByStartDateBetween	… where x.startDate between ?1 and ?2
LessThan	findByAgeLessThan	… where x.age < ?1
LessThanEqual	findByAgeLessThanEqual	… where x.age ⇐ ?1
GreaterThan	findByAgeGreaterThan	… where x.age > ?1
GreaterThanEqual	findByAgeGreaterThanEqual	… where x.age >= ?1
After	findByStartDateAfter	… where x.startDate > ?1
Before	findByStartDateBefore	… where x.startDate < ?1
IsNull	findByAgeIsNull	… where x.age is null
IsNotNull,NotNull	findByAge(Is)NotNull	… where x.age not null
Like	findByFirstnameLike	… where x.firstname like ?1
NotLike	findByFirstnameNotLike	… where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	… where x.firstname like ?1 (parameter bound with appended %)
EndingWith	findByFirstnameEndingWith	… where x.firstname like ?1 (parameter bound with prepended %)
Containing	findByFirstnameContaining	… where x.firstname like ?1 (parameter bound wrapped in %)
OrderBy	findByAgeOrderByLastnameDesc	… where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	… where x.lastname <> ?1
In	findByAgeIn(Collection ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection age)	… where x.age not in ?1
TRUE	findByActiveTrue()	… where x.active = true
FALSE	findByActiveFalse()	… where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	… where UPPER(x.firstame) = UPPER(?1)		

常用如下:
And --- 等价于 SQL 中的 and 关键字,比如 findByUsernameAndPassword(String user, Striang pwd)
Or --- 等价于 SQL 中的 or 关键字,比如 findByUsernameOrAddress(String user, String addr)
Between --- 等价于 SQL 中的 between 关键字,比如 findBySalaryBetween(int max, int min)
LessThan --- 等价于 SQL 中的 "<",比如 findBySalaryLessThan(int max)
GreaterThan --- 等价于 SQL 中的">",比如 findBySalaryGreaterThan(int min)
IsNull --- 等价于 SQL 中的 "is null",比如 findByUsernameIsNull()
IsNotNull --- 等价于 SQL 中的 "is not null",比如 findByUsernameIsNotNull()
NotNull --- 与 IsNotNull 等价
Like --- 等价于 SQL 中的 "like",比如 findByUsernameLike(String user)
NotLike --- 等价于 SQL 中的 "not like",比如 findByUsernameNotLike(String user)
OrderBy ---等价于 SQL 中的 "order by",比如 findByUsernameOrderBySalaryAsc(String user)
Not --- 等价于 SQL 中的 "! =",比如 findByUsernameNot(String user)
In --- 等价于 SQL 中的 "in",比如 findByUsernameIn(Collection<String> userList) ,方法的参数可以是 Collection 类型,也可以是数组或者不定长参数
NotIn --- 等价于 SQL 中的 "not in",比如 findByUsernameNotIn(Collection<String> userList) ,方法的参数可以是 Collection 类型,也可以是数组或者不定长
		
		
		
	@Autowired
	private ArticleRepository articleRepository;

	@RequestMapping("/mysql")
	@ResponseBody
	public String mysql() {
		articleRepository.save(new Article("Neo", "Chen"));
		for (Article article : articleRepository.findAll()) {
			System.out.println(article);
		}
		Article tmp = articleRepository.findByTitle("Neo");
		return tmp.getTitle();
	}

	@RequestMapping("/search")
	@ResponseBody
	public String search() {

		
		for (Article article : articleRepository.findBySearch(1)) { System.out.println(article); }
		 
		List<Article> tmp = articleRepository.findBySearch(1L);

		tmp.forEach((temp) -> {
			System.out.println(temp.toString());
		});

		return tmp.get(0).getTitle();
	}
		
		

5.3.3.1. 传递枚举参数

			
package cn.netkiller.api.repository;

import org.springframework.data.repository.CrudRepository;

import cn.netkiller.api.domain.StatisticsHistory;

public interface StatisticsHistoryRepostitory extends CrudRepository<StatisticsHistory, Long> {

	public StatisticsHistory findByMemberIdAndStatisticsIdAndType(long member_id, long statistics_id,
			StatisticsHistory.StatisticsType type);

}
			
			

			
	@Autowired
	private StatisticsHistoryRepostitory statisticsHistoryRepostitory;			
			
	statisticsHistoryRepostitory.findByMemberIdAndStatisticsIdAndType(uid, id, type);
			
			

5.3.3.2. 翻页操作

			
package cn.netkiller.api.repository;

import java.util.List;

import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.CrudRepository;

import cn.netkiller.api.domain.RecentRead;

public interface RecentReadRepostitory extends CrudRepository<RecentRead, Long> {

	List<RecentRead> findByMemberId(long id, Pageable pageable);

}
			
			

Top 10 实例

			
	@RequestMapping("/recent/read/list/{id}")
	public List<RecentRead> recentList(@PathVariable long id) {
		int page = 0;
		int limit = 10;
		List<RecentRead> recentRead = recentReadRepostitory.findByMemberId(id, new PageRequest(page, limit));
		return recentRead;
	}
			
			

5.3.3.3. 排序操作操作

			
List<UserModel> findByName(String name, Sort sort);
			
			

			
Sort sort = new Sort(Direction.DESC, "id"); 
repostitory.findByName("Neo", sort);
			
			

5.3.3.4. OrderBy

			
public List<StudentEntity> findAllByOrderByIdAsc();
public List<StudentEntity> findAllByOrderByIdDesc();
List<RecentRead> findByMemberIdOrderByIdDesc(int memberId, Pageable pageable);
			
			

5.3.3.5. Query

5.3.3.5.1. 参数传递
				
package api.repository.oracle;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import api.domain.oracle.Member;

@Repository
public interface MemberRepository extends CrudRepository<Member, Long> {
	public Page<Member> findAll(Pageable pageable);

	// public Member findByBillno(String billno);

	public Member findById(String id);

	@Query("SELECT m FROM Member m WHERE m.status = 'Y' AND m.id = :id")
	public Member findFinishById(@Param("id") String id);

}
				
				
				
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

public interface PersonRepository extends JpaRepository<Person, Long> {
    @Query("SELECT p FROM Person p WHERE LOWER(p.lastName) = LOWER(:lastName)")
    public List<Person> find(@Param("lastName") String lastName);
}
				
				

5.3.3.6. @Transactional

5.3.3.6.1. 删除更新需要 @Transactional 注解
				
package cn.netkiller.api.repository;

import javax.transaction.Transactional;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import cn.netkiller.api.domain.RecentRead;

@Repository
public interface RecentReadRepostitory extends CrudRepository<RecentRead, Integer> {

	Page<RecentRead> findByMemberIdOrderByIdDesc(int memberId, Pageable pageable);

	int countByMemberId(int memberId);
	
	@Transactional
	@Modifying
	@Query("DELETE FROM RecentRead r WHERE r.memberId = ?1 AND r.articleId = ?2")
	void deleteByMemberIdAndArticleId(int memberId, int articleId);
	
	@Transactional
	@Modifying
	@Query("delete from RecentRead where member_id = :member_id")
	public void deleteByMemberId(@Param("member_id") int memberId);

	int countByMemberIdAndArticleId(int memberId, int articleId);

}				
				
				
5.3.3.6.2. 回滚操作
				
	// 指定Exception回滚
	@Transactional(rollbackFor=Exception.class)
    public void methodName() {
       // 不会回滚
       throw new Exception("...");
    }

	//指定Exception回滚,但其他异常不回滚
	@Transactional(noRollbackFor=Exception.class)
    public ItimDaoImpl getItemDaoImpl() {
        // 会回滚
        throw new RuntimeException("注释");
    }
				
				

5.3.4. CrudRepository

CrudRepository 接口提供了最基本的对实体类的添删改查操作

		
T save(T entity);								//保存单个实体 
Iterable<T> save(Iterable<? extends T> entities);//保存集合        
T findOne(ID id);								//根据id查找实体         
boolean exists(ID id);							//根据id判断实体是否存在         
Iterable<T> findAll();							//查询所有实体,不用或慎用!         
long count();									//查询实体数量         
void delete(ID id);								//根据Id删除实体         
void delete(T entity);							//删除一个实体 
void delete(Iterable<? extends T> entities);		//删除一个实体的集合         
void deleteAll();								//删除所有实体,不用或慎用! 		
		
		
		
public interface UserRepository extends CrudRepository<User, Long> {

    Long countByFirstName(String firstName);

    @Transactional
    Long deleteByFirstName(String firstName);

    @Transactional
    List<User> removeByFirstName(String firstName);

}
		
		

5.3.5. JpaRepository