与mysql数据库的连接-Java EE

问题描述 投票:0回答:1

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。

这是项目的结构:enter image description here

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));
    }
}
mysql jpa entitymanager java-ee-7 persistence.xml
1个回答
0
投票

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

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