WELD-001408：在注入点 [BackedAnnotatedField] @Inject 具有限定符 @Default 的类型 UserService 的依赖关系不满足

Question

@Inject 时出现错误。我不明白为什么。

我的应用服务器：GlassFish 4.1.2

当我@Inject我创建的类时服务器报错

java.io.IOException: com.sun.enterprise.admin.remote.RemoteFailureException: Error occurred during deployment: Exception while loading the app : CDI deployment failure:WELD-001408: Unsatisfied dependencies for type UserService with qualifiers @Default at injection point [BackedAnnotatedField] @Inject private jobs.SignUpCDIB.userServiceat jobs.SignUpCDIB.userService(SignUpCDIB.java:0)

当我 @Inject 我创建的类时服务器出错

package jobs;

import services.UserService;
import javax.enterprise.context.ConversationScoped;
import javax.inject.Inject;
import javax.inject.Named;
import java.io.Serializable;

@Named
@ConversationScoped
public class SignUpCDIB implements Serializable {

    private static final long serialVersionUID = 1L;

    @Inject
    private UserService userService;
}

我正在尝试将其注入另一个类，例如：

package services;

import jobs.User;

public interface UserService {

    void save(User user);
}

UserService实现java类

package services;

import jobs.User;

import java.io.Serializable;

public class UserServiceImpl implements UserService, Serializable {
    @Override
    public void save(User user) {

    }
}

Maven pom xml 文件

<?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>groupId</groupId>
    <artifactId>loginTutorials1</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.2.13</version>
        </dependency>
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.2.13</version>
        </dependency>

        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </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>
    </dependencies>
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>1.8</source>
                        <target>1.8</target>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>```

Answer 1

您收到此错误的原因可以从 DI 容器生成的错误消息中看出。如您所见：

Unsatisfied dependencies for type UserService with qualifiers @Default at injection point

容器会通知您，对于请求的实现，没有适合注入的 bean（即 UserService 就是这种情况）。

添加@Singleton 注释使其对 DI 容器可见，同时自动符合注入条件。

有问题的注释的工作方式与您在其他类中的@ConversationScoped 几乎相同，尽管在 bean 的可用范围方面存在一些差异。

我建议你好好阅读一下 bean 和 DI 的一般处理方式。