Could not instantiate bean class [javax.servlet.ServletContext]: Specified class is an interface

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#spring #servlet #context

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本文介绍了一个关于Spring MVC框架中使用@Autowired注解注入ServletContext接口时遇到的问题及解决办法。该问题表现为无法实例化接口类型，导致启动失败。通过添加spring-instrument依赖解决了这一难题。

环境:

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <!--spring framework-->
        <spring-framework.version>3.2.17.RELEASE</spring-framework.version>
        <!--eclipselink jpa -->
        <eclipselink.version>2.5.2</eclipselink.version>
        <!-- Logging -->
        <slf4j.version>1.6.4</slf4j.version>
    </properties>

异常栈:

org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [javax.servlet.ServletContext]: Specified class is an interface
    org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:102)
    org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:135)
    org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:80)
    org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:103)
    org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)
    org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:743)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:672)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:82)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:933)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:867)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:951)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:827)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.sitemesh.webapp.contentfilter.ContentBufferingFilter.bufferAndPostProcess(ContentBufferingFilter.java:169)
    org.sitemesh.webapp.contentfilter.ContentBufferingFilter.doFilter(ContentBufferingFilter.java:126)
    org.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:120)
    org.sitemesh.config.ConfigurableSiteMeshFilter.doFilter(ConfigurableSiteMeshFilter.java:163)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)

代码:

/**
 * 成员控制器
 * @author xiaofanku@live.cn
 * @since 20170505
 */
@Controller
@RequestMapping(value="/member")
public class ForumMemberController {
    @Autowired
    private ServletContext servletContext;
    //ETC
    @RequestMapping(value="{id}.png", method=RequestMethod.GET, produces="image/png")
    @ResponseBody
    public byte[] getMemberAvatar(
            @PathVariable("id")int memberId, 
            HttpServletResponse response, 
            Model model){
        String filename = servletContext.getRealPath(imgstore+"/avatar/empty.gif");
        File avatarFile=new File(filename);
        try{
            byte[] bytes=FileUtils.readFileToByteArray(avatarFile);
            response.addHeader("Content-Disposition", "inline;filename=\"avatar.jpg\"");
            Date date =new Date();
            response.setDateHeader("Last-Modified",date.getTime()); 
            response.setDateHeader("Expires",date.getTime()+60*60*24); 
            response.setHeader("Cache-Control", "public"); 
            response.setHeader("Pragma", "Pragma"); 
            response.setStatus(HttpServletResponse.SC_OK);
            return bytes;
        }catch(IOException e){
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }
    }
}

Spring依赖:

        <!-- spring MVC framework -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <!-- spring framework-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <!-- 连接池 -->
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.20</version>
        </dependency>
        <!-- spring tx-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring-framework.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <!-- orm -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <!-- java unit test -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring-framework.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

触决: 增加spring-instrument依赖

        <!-- -javaagent/InstrumentationLoadTimeWeaver -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-instrument</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>