Java EntityManager为null，带有@PersistenceContext [英] Java EntityManager null with @PersistenceContext

问题描述

我正在使用Jersey的Wildfly 10，并通过@Inject注入依赖项.我有DAO和Service接口，并在CustomBinder中声明了它们的实现.注入效果很好，但是 EntityManager 被注入 null 并带有 @PersistenceContext 批注.我正在使用MySQL，并且数据源测试连接正在工作.

I'm using Wildfly 10, Jersey, and injecting dependencies with @Inject. I have DAO and Service interfaces with their implementations declared in a CustomBinder. The injections work well, but the EntityManager is injected null with the @PersistenceContext annotation. I'm using MySQL and the datasource test-connection is working.

API Rest类

@Path("/account")
public class CuentaServiceRS {

    @Inject
    private ICuentaService cuentaService;

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Cuenta getCuenta() {
        return cuentaService.getCuentas().get(0);       
    }

}

ICuentaService

@Stateless
public class CuentaServiceImpl implements ICuentaService {

    @Inject
    private ICuentaDAO cuentaDAO;

    @Override
    public List<Cuenta> getCuentas() {
        List<Cuenta> cuentas = cuentaDAO.getAllCuentas();
        cuentas;
    }

}

CuentaDAO

@Stateless
public class CuentaDAOImpl implements ICuentaDAO {

    @PersistenceContext(unitName = "altitudePU")
    protected EntityManager em;

    @Override
    public List<Cuenta> getAllCuentas() {
        CriteriaQuery<Cuenta> cq = em.getCriteriaBuilder().createQuery(Cuenta.class);

        /...

        return resultlist;
    }

}

我在 persistence.xml

<persistence-unit name="altitudePU">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>java:jboss/datasources/AltitudePU</jta-data-source>
    <class>ar.com.olx.domain.Cuenta</class>
    <properties>
        <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.jdbc2.optional.MysqlXADataSource" />
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
    </properties>    
</persistence-unit>

在 web.xml

<servlet>
        <servlet-name>altitudeservlet</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
        <init-param>
            <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
            <param-value>true</param-value>
        </init-param>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>ar.com.villat.bind.ApplicationJaxRS</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
</servlet>

我的自定义 AplicationJaxRS ，它从ResourceConfig扩展而来

My custom AplicationJaxRS which extendes from ResourceConfig

public class ApplicationJaxRS extends ResourceConfig {

    public ApplicationJaxRS(){
        register(new CustomBinder());
        packages(true, "ar.com.olx");
    }

}

CustomBinder

public class CustomBinder extends AbstractBinder {

    @Override
    protected void configure() {
        bind(CuentaServiceImpl.class).to(ICuentaService.class);
        bind(CuentaDAOImpl.class).to(ICuentaDAO.class);
    }

}

最后，我与该帖子有关的 pom.xml 依赖项

And finally, my pom.xml dependencies related to this post

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>2.22.2</version>
</dependency>

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>javax.enterprise</groupId>
    <artifactId>cdi-api</artifactId>
    <version>1.2</version>
</dependency>

<dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>7.0</version>
</dependency>

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-annotations</artifactId>
    <version>3.5.6-Final</version>
</dependency>

<dependency>
    <groupId>org.hibernate.javax.persistence</groupId>
    <artifactId>hibernate-jpa-2.1-api</artifactId>
    <version>1.0.0.Final</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>org.jboss.spec.javax.ejb</groupId>
    <artifactId>jboss-ejb-api_3.2_spec</artifactId>
    <version>1.0.0.Final</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.39</version>
</dependency>

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.4</version>
</dependency>

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
</dependency>

<dependency>
    <groupId>dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>1.6.1</version>
    <scope>provided</scope>
</dependency>

如果您需要更多信息，请告诉我.

If you need more information, please tell me.

推荐答案

当您使用全栈JavaEE服务器时，可以大大简化这一过程.

As you are using a full stack JavaEE server you can simplify this a lot.

如果您尚未将MySQL数据源添加到WildFly，则可以这样做:

If you have not added a MySQL datasource to WildFly then you can do it like this:

1. 创建一个名为deploy-mysql-ds.cli的文件，其内容如下:

1. Create a file called deploy-mysql-ds.cli with the following content:

# Execute offline
embed-server --server-config=standalone.xml

deploy $HOME/.m2/repository/mysql/mysql-connector-java-5.1.39.jar

# Add the application datasource
data-source add \
    --name=AltitudeDS \
    --driver-name=mysql-connector-java-5.1.39.jar \
    --connection-url=jdbc:mysql://localhost:3306/altitudeDB \
    --jndi-name=java:jboss/datasources/AltitudePU \
    --user-name=$USER_NAME \
    --password=$PASSWORD

用实际值替换$HOME，$USER_NAME和$PASSWORD

通过像下面这样执行来在Wildfly中配置数据源:

Configure the data source in Wildfly by executing it like:

$JBOSS_HOME/bin/jboss-cli.sh --file="deploy-mysql-ds.cli"

您只需要执行一次.

请注意，--jndi-name与中的<jta-data-source>...</jta-data-source>相匹配 您的persistence.xml文件.

Note that the --jndi-name matches the <jta-data-source>...</jta-data-source> in your persistence.xml file.

您不需要在maven依赖项中使用mysql-connector-java-5.1.39.jar，因为它已直接添加到服务器中.还有其他解决方案，涉及将jar添加为模块" 但我发现这种方法要简单得多.

You do not need the mysql-connector-java-5.1.39.jar in your maven dependencies because it has been added to the server directly. There are other solutions that involve adding the jar as a "module" but I find this way to be much simpler.

如下修改您的应用程序:

Amend your application as follows:

1. 删除所有冗余依赖项:

1. Remove all the redundant dependencies:

<dependencies>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>7.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.4</version>
    </dependency>
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.5</version>
    </dependency>
</dependencies>

删除AplicationJaxRS和CustomBinder类并添加JAXRSConfiguration类:

Remove the AplicationJaxRS and CustomBinder classes and add a JAXRSConfiguration class:

/**
 * Configures a JAX-RS endpoint
 */
@ApplicationPath("resources")
public class JAXRSConfiguration extends Application {
}

从web.xml中删除altitudeservlet.如果只有它，则完全删除整个文件.

Remove the altitudeservlet from the web.xml. If that is the only thing in it then completely remove the whole file.

测试

您应该能够部署此Web应用程序并从以下位置访问它:

Test it

You should be able to deploy this web application and access it from:

http://localhost:8080/altitude-webapp/resources/account

其中altitude-webapp是您的WAR文件的名称.

where altitude-webapp is the name of your WAR file.

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