我试图创建一个Java EE应用程序,我正在努力与数据库建立连接(我正在使用mysql),而我使用的是payara4。我还尝试在服务器上创建一个连接池,但是它没有也不行。您能给我一些有关我应该修改什么的提示吗?谢谢。
persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="Planner" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<!-- <class>model.Task</class>-->
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/planner"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value="root"/>
<!--Hibernate properties-->
<!-- <property name="hibernate.show_sql" value="false"/>-->
<!-- <property name="hibernate.format_sql" value="false"/>-->
<!-- <property name="hibernate.hbm2ddl.auto" value="create"/>-->
<!-- <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>-->
</properties>
</persistence-unit>
</persistence>
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.example</groupId>
<artifactId>planner-backend1</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.1-api</artifactId>
<version>1.0.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.3.5.Final</version>
</dependency>
<dependency>
<groupId>org.flywaydb</groupId>
<artifactId>flyway-core</artifactId>
<version>4.2.0</version>
<!-- scope is set to test, to avoid having the dependency in the wars -->
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<!-- this is the version, payara uses -->
<version>5.1.2.Final</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
任务实体和任务存储库看起来像这样:
@Entity(name = "task")
public class Task {
@Id
@GeneratedValue
private Long id;
@Column
private String description;
@Column
private String date;
存储库
@Transactional(Transactional.TxType.SUPPORTS)
public class TaskRepository {
@PersistenceContext(unitName = "Planner")
private EntityManager entityManager;
public Task find(@NotNull Long id) {
return entityManager.find(Task.class, id);
}
public List<Task> findAll() {
TypedQuery<Task> query = entityManager.createQuery("SELECT b FROM Task b ORDER BY b.id DESC", Task.class);
return query.getResultList();
}
public Long countAll() {
TypedQuery<Long> query = entityManager.createQuery("SELECT count(b) FROM Task b", Long.class);
return query.getSingleResult();
}
@Transactional(Transactional.TxType.REQUIRED)
public void create(@NotNull Task task) {
entityManager.persist(task);
}
@Transactional(Transactional.TxType.REQUIRED)
public void delete(@NotNull Long id) {
entityManager.remove(entityManager.getReference(Task.class, id));
}
}
您可以使用Mysql JDBC,这是用于连接数据库的简单Java库。
https://dev.mysql.com/doc/connector-j/5.1/en/connector-j-usagenotes-connect-drivermanager.html