本篇内容主要讲解“如何快速搞定Jpa”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“如何快速搞定Jpa”吧!
数据准备
数据库使用的数据表设计如下
建表语句如下
SET NAMES utf8mb4; SET FOREIGN_KEY_CHECKS = 0; -- ---------------------------- -- Table structure for t_user -- ---------------------------- DROP TABLE IF EXISTS `t_user`; CREATE TABLE `t_user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `user_name` varchar(255) DEFAULT NULL, `password` varchar(255) DEFAULT NULL, `last_login_time` datetime DEFAULT NULL, `sex` tinyint(4) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=armscii8; -- ---------------------------- -- Records of t_user -- ---------------------------- BEGIN; INSERT INTO `t_user` VALUES (1, 'json', '123', '2019-07-27 16:01:21', 1); INSERT INTO `t_user` VALUES (2, 'jack jo', '123', '2019-07-24 16:01:37', 1); INSERT INTO `t_user` VALUES (3, 'manistal', '123', '2019-07-24 16:01:37', 1); INSERT INTO `t_user` VALUES (4, 'landengdeng', '123', '2019-07-24 16:01:37', 1); INSERT INTO `t_user` VALUES (5, 'max', '123', '2019-07-24 16:01:37', 1); COMMIT; SET FOREIGN_KEY_CHECKS = 1;新建 Spring Boot 工程
选择 File -> New -> Project 选择 Spring Initializr，选择 next 填写包名，项目名，选择下一步。选择依赖，Spring web starter 前面打钩，sql 选项为 Spring Data Jpa，MySql 项目名任意
引入 Pom配置
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-webflux</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>io.projectreactor</groupId> <artifactId>reactor-test</artifactId> <scope>test</scope> </dependency> </dependencies>编写配置文件 application.yml
server: port: 8086 spring: #通用的数据源配置 datasource: driverClassName: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/demo_test?useSSL=false&useUnicode=true&characterEncoding=utf8 username: root password: 123 jpa: #这个参数是在建表的时候，将默认的存储引擎切换为 InnoDB 用的 database-platform: org.hibernate.dialect.MySQL5InnoDBDialect #配置在日志中打印出执行的 SQL 语句信息。 show-sql: true hibernate: #配置指明在程序启动的时候要删除并且创建实体类对应的表 ddl-auto: create编写示例代码
新建实体对象 UserDao.java
实体类，需要使用 @Entity 注解标注 需要对实体类的属性进行标注，使用 @Id 标注组件 使用 @Column 标注非主键
@Entity @Table(name="t_user") public class UserDO { @Id private Integer id; @Column(name="user_name",length = 200) private String userName; @Column(name="password",length = 200) private String password; @Column(name="sex") private Integer sex; @Column(name="last_login_time") private Date lastLoginTime; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public Integer getSex() { return sex; } public void setSex(Integer sex) { this.sex = sex; } public Date getLastLoginTime() { return lastLoginTime; } public void setLastLoginTime(Date lastLoginTime) { this.lastLoginTime = lastLoginTime; } }新建仓库接口类 UserRepository
仓库接口类，UserRepository 是我们常用的 Dao 接口，需要注意
使用 @Repository 注解
继承 JPARepository
UserRepository 不需要编写任何代码，即可实现增删查改
@Repository public interface UserRepository extends JPARepository<UserDO,Integer> { }编写测试用例
在
src/test/java/com/fishpro/jpa/下，新增加
UserRepositoryTest.java使用
@RunWith(SpringRunner.class)和
@SpringBootTest注解标注类。
@RunWith(SpringRunner.class) @SpringBootTest public class UserRepositoryTest{ }新增加用户数据
@Before public void before(){ UserDO userDO=new UserDO(); userDO.setId(1); userDO.setUserName("fishpro"); userDO.setSex(1); userDO.setLastLoginTime(new Date()); userDO.setPassword("passWord"); userRepository.save(userDO); }查询单个用户数据
@Test public void testFind(){ Optional<UserDO> optionalUserDO=userRepository.findById(1); if(optionalUserDO.isPresent()){ UserDO userDO=optionalUserDO.get(); System.out.println("testFind user"+userDO.getUserName()); } }查询多个数据
@Test public void testFindAll(){ List<UserDO> list=userRepository.findAll(); for (UserDO user:list ) { System.out.println("user_name:"+user.getUserName()); } }更新数据
@Test public void testUpdate(){ Optional<UserDO> optionalUserDO=userRepository.findById(1); if(optionalUserDO.isPresent()){ UserDO userDO=optionalUserDO.get(); userDO.setUserName("fishpro001"); userRepository.save(userDO); System.out.println("testFind user"+userDO.getUserName()); } }删除数据
@After public void after(){ userRepository.deleteById(1); userRepository.deleteById(2); userRepository.deleteById(3); }联合主键
例如定义表中userId，roleId 都是主键，此时这样设置
1.定义一个主键类
public class UserRoleKey implements Serializable { private Integer userId; private Integer roleId; }2.定义实体类
@Entity @Table(name="t_user_role") @IdClass(UserRoleKey.class) //注意这里是引入了 定义的符合主键类 public class UserRoleDO { @Id private Integer userId; @Id private Integer roleId; public Integer getUserId() { return userId; } public void setUserId(Integer userId) { this.userId = userId; } public Integer getRoleId() { return roleId; } public void setRoleId(Integer roleId) { this.roleId = roleId; } }到此，相信大家对“如何快速搞定Jpa”有了更深的了解，不妨来实际操作一番吧！这里是编程网网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
