java - 模型未注入(inject)到 servlet 中

Question

我有一个简单的 servlet 项目:我需要将依赖项注入(inject)一个 servlet 实例。我尝试了几种注释:Default、Singlton、EJB、ManagedBean，但没有任何帮助。

POM.xml的一部分

<build>
    <resources>
        <resource>
          <directory>src/main/resources</directory>
        </resource>
    </resources>
    <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>

                <compilerArguments>
                    <endorseddirs>${endorsed.dir}</endorseddirs>
                </compilerArguments>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>2.3</version>
            <configuration>
                <failOnMissingWebXml>false</failOnMissingWebXml>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.6</version>
            <executions>
                <execution>
                    <phase>validate</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${endorsed.dir}</outputDirectory>
                        <silent>true</silent>
                        <artifactItems>
                            <artifactItem>
                                <groupId>javax</groupId>
                                <artifactId>javaee-endorsed-api</artifactId>
                                <version>7.0</version>
                                <type>jar</type>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

小服务程序

@WebServlet(urlPatterns = {"/updater_servlet"},loadOnStartup = 1)
public class Updater_servlet extends HttpServlet
{
    private final static org.slf4j.Logger logger = LoggerFactory.getLogger(Updater_servlet.class);

    @Inject
    private UpdatesModel updates;

    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        ...
    }

模型类

@Model
public class UpdatesModel implements Serializable
{
    private final static org.slf4j.Logger logger = LoggerFactory.getLogger(UpdatesModel.class);

    private final String url;
    private final String username;
    private final String password;
    private final String instpath;

    public UpdatesModel()
    {
        Properties prop = new Properties();

        try
        {
            Class.forName(driverName);
            prop.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("config.properties"));
        }
        catch (ClassNotFoundException|IOException ex)
        {
            Logger.getLogger(UpdatesModel.class.getName()).log(Level.SEVERE, null, ex);
        }

        url          = "jdbc:mysql://" + serverName + "/" + prop.getProperty("database","");
        username     = prop.getProperty("dbuser","");
        password     = prop.getProperty("dbpassword","");

        instpath     = prop.getProperty("instpath","");
    }

更新字段永远不会被初始化。它等于空。我做错了什么？

更新:依赖项:

<dependencies>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.7</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>jcl-over-slf4j</artifactId>
        <version>1.7.7</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.7</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>javax.enterprise</groupId>
        <artifactId>cdi-api</artifactId>
        <version>1.2</version>
        <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-core</artifactId>
        <version>1.10.8</version>
        <scope>test</scope>
    </dependency>
</dependencies>

我在 WEB-INF 中创建了空的 beans.xml - 没有帮助((我部署到 Tomcat 7。还尝试了 tomcat 8 - 没有区别((

Answer 1

首先，您的 pom.xml block 与问题完全无关；) 依赖项部分会更有趣。

在 WEB-INF 目录中创建或确保它存在名为 beans.xml 的空文件。

确保在 pom.xml 中定义了 cdi-api 依赖项:

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

还要确保将 war 部署到支持 CDI 的应用程序服务器(如 Wildfly (JBoss))中，或者如果它只是 servlet 容器(如 Tomcat)，请确保在类路径中具有所有必要的库。

将具体实现注入(inject)接口(interface)也是一种很好的做法，因此您的 UpdatesModel 类应该实现一些指定其行为的接口(interface)。但这不是必需的。

编辑:只有在 SE 环境中才需要对焊接的依赖。在 EE 中，所有需要的应该是 cdi-api。