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Java EE 7 CDI-注入不起作用，发送NullPointerException

更新时间：2023-12-03 13:33:04

因此，我可以在这里解决问题我所做的就是：



Maven依赖项



javax：javaee-api 足以使用Java EE 7的功能。我已经将依赖项添加到 javax.enterprise：cdi-api ， javax.inject：javax.inject 和 javax.annotation：javax.annotation-api



beans.xml



这只是战争档案中的一个大型项目。我已将bean.xml放在 src / main / webapp / WEB-INF 下（是否有必要将它与Wildfly一起使用？不知道）



Vaadin CDIUI



这就是解决我的问题的方法。我尝试使用Vaadin CDIUI失败。 Vaadin实际上是使用 new 操作初始化UI类的。由于它不是由容器管理的，因此每个注入点都无法正常工作（我首先通过对视图和控制器执行 new 操作来解决该问题，我已经描述过）



我已经重构了所有内容，因此在视图和控制器中使用了注入，并且添加了 @CDIUI 到我的Vaadin UI。最后，我还为此结果添加了新参数到servlet配置（ UIProvider ）中：

  @Theme（变色龙绿色）
 @Title（数据管理器）
 @CDIUI（）
公共类DataManagerUI扩展UI {
 @WebServlet（value = / *，
 asyncSupported = true，
 initParams = {@WebInitParam（
 name = session-timeout，
 value = 60 
），@ WebInitParam（
 name = UIProvider，
 value = com.vaadin.cdi.CDIUIProvider 
）} 
）
 @VaadinServletConfiguration（productionMode = false，
 ui = DataManagerUI.class，
 closeIdleSessions = true 
）
公共静态类Servlet扩展了VaadinServlet {
} 

 [...] 
}

通常用 new 操作ramework，UI类应该由 UIProvider 在使用Injection时给出。



感谢帮助！

p>

I have a problem with my injection, it's the first time I try it. I'm working with Wildfly and Java EE 7. I've got a NullPointerException when trying to access Authenticator instance in LoginController.

I use maven, my beans.xml is found under src/main/webapp/META-INF but I'v tried to put it in src/main/webapp/WEB-INF/classes without success.

Here is my code :

The class to inject :

@Stateless
public class Authenticator {

    @Inject
    HashGenerator hashGenerator;

    @Inject
    UserPersistance userPersistance;

    public boolean authenticate(final String username, final String password) {
        User user = userPersistance.getUser(username);
        String salt = user.getSalt();
        String hash = hashGenerator.hash(password, salt);
        return user.getPassword().equals(hash);
    }
}

The controller which throw NullPointerException :

@Stateless
public class LoginController {

    @Inject
    Authenticator authenticator;

    public void login(String username, String password) {
        if (authenticator.authenticate(username, password)) {
            UI ui = UI.getCurrent();
            ui.getSession().setAttribute(SessionAttribute.USER.getAttributeName(), username);
            ui.getNavigator().navigateTo(MainView.getName());
        }
    }
}

And my beans.xml (Under src/main/webapp/META-INF)

<beans
    xmlns="http://xmlns.jcp.org/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
    bean-discovery-mode="all">
</beans>

What did I do wrong?

UPDATE

Sorry, I previously miswritten the folders name of beans.xml.

So, just to be clear, maven generate a WAR archive, and I've previously tried to put beans.xml under META-INF , WEB-INF and WEB-INF/classes. None of those folder seems to make it work. I've checked (tried and it works) a quickstart project from JBoss AS 7, and they put beans.xml under WEB-INF. I've done the same.

I think that maybe it comes from my Maven configuration. Here it is :

<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>be.normegil</groupId>
    <artifactId>datamanager</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>datamanager</name>

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.target>1.7</maven.compiler.target>
        <maven.compiler.source>1.7</maven.compiler.source>        
        <failOnMissingWebXml>false</failOnMissingWebXml>
        <maven.build.timestamp.format>yyyy-MM-dd'T'HH:mm:ss</maven.build.timestamp.format>
        <vaadin.version>7.1.9</vaadin.version>
        <vaadin.plugin.version>${vaadin.version}</vaadin.plugin.version>
    </properties>
    <pluginRepositories>
        <pluginRepository>
            <id>vaadin-snapshots</id>
            <url>http://oss.sonatype.org/content/repositories/vaadin-snapshots/</url>
            <releases>
                <enabled>false</enabled>
            </releases>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
        </pluginRepository>
    </pluginRepositories>
    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>7.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.enterprise</groupId>
            <artifactId>cdi-api</artifactId>
            <version>1.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.annotation</groupId>
            <artifactId>javax.annotation-api</artifactId>
            <version>1.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.ejb</groupId>
            <artifactId>javax.ejb-api</artifactId>
            <version>3.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.transaction</groupId>
            <artifactId>javax.transaction-api</artifactId>
            <version>1.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
            <version>1.0.2</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-server</artifactId>
            <version>${vaadin.version}</version>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-client-compiled</artifactId>
            <version>${vaadin.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-themes</artifactId>
            <version>${vaadin.version}</version>
        </dependency>
        <dependency>
            <groupId>com.vaadin</groupId>
            <artifactId>vaadin-cdi</artifactId>
            <version>1.0.0.alpha1</version>
        </dependency>
        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-all</artifactId>
            <version>1.9.5</version>
        </dependency>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
            <version>10.7.1.1</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.wildfly.plugins</groupId>
                <artifactId>wildfly-maven-plugin</artifactId>
                <version>1.0.0.Beta1</version>
            </plugin>
        </plugins>
    </build>

</project>

So, I was able to fix my problem, here is what I've done :

Maven dependencies

I was assuming that javax:javaee-api was enough to use the functionnalities of Java EE 7. I've added dependencies to javax.enterprise:cdi-api, javax.inject:javax.inject and javax.annotation:javax.annotation-api

beans.xml

It's only one big project build into a war archive. I've put my beans.xml under src/main/webapp/WEB-INF (Is it necessary to have it at all with Wildfly ? Don't know)

Vaadin CDIUI

That's what solved my issue. I've tried to use Vaadin CDIUI without success. Vaadin was actually initializing my UI class with a new operation. Since it was not managed by the container, every Injection points didn't work (I've first fix it by doing new operations on my views and controllers, falling on the problem I've described)

I've refactored everything so injection is used in the views and controllers, and I've added @CDIUI to my Vaadin UI. Last, I've also added a new parameter to my servlet configuration (UIProvider) for this result :

@Theme("chameleon-green")
@Title("Data Manager")
@CDIUI("")
public class DataManagerUI extends UI {
    @WebServlet(value = "/*",
            asyncSupported = true,
            initParams = {@WebInitParam(
                    name = "session-timeout",
                    value = "60"
            ),@WebInitParam(
                    name = "UIProvider",
                    value = "com.vaadin.cdi.CDIUIProvider"
            )}
    )
    @VaadinServletConfiguration(productionMode = false,
            ui = DataManagerUI.class,
            closeIdleSessions = true
    )
    public static class Servlet extends VaadinServlet {
    }

    [...]
}

When normally instantiated with new operation from Vaadin framework, the UI class should be given by the UIProvider when using Injection.

Thanks for the help !

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