使用MultipartResolver進行Spring文件上傳。空指針異常

這次我試圖用Spring實現文件上傳到服務器。但也可以通過文件上傳控制器獲取NullPointerException。使用MultipartResolver進行Spring文件上傳。空指針異常

MVC-調度員的servlet：

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xmlns:tx="http://www.springframework.org/schema/tx" 
     xmlns:context="http://www.springframework.org/schema/context" 
     xsi:schemaLocation="http://www.springframework.org/schema/beans 
       http://www.springframework.org/schema/beans/spring-beans-2.5.xsd 
       http://www.springframework.org/schema/aop 
       http://www.springframework.org/schema/aop/spring-aop-2.5.xsd 
       http://www.springframework.org/schema/context 
       http://www.springframework.org/schema/context/spring-context-2.5.xsd 
       http://www.springframework.org/schema/tx 
       http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"> 

    <bean id="multipartResolver" 
      class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
     <property name="maxUploadSize" value="100000000"/> 
    </bean> 

    //Other beans... 

</beans>

控制器方法：


@RequestMapping(value = "/uploadAvatar", method = RequestMethod.POST) 
public String uploadAvatar(@ModelAttribute("avatar") UploadedFile uploadedFile, BindingResult result) { 
    InputStream inputStream = null; 
    OutputStream outputStream = null; 

    System.out.println(uploadedFile.getFile().isEmpty()); //[Line21] Here I have NullPointerException 

    MultipartFile file = uploadedFile.getFile(); 
    String fileName = file.getName(); 

    if(result.hasErrors()) return "profile"; 

    try { 
     inputStream = file.getInputStream(); 
     File newFile = new File("/resources/img/" + fileName); 
     outputStream = new FileOutputStream(newFile); 
     int read = 0; 
     byte[] bytes = new byte[1024]; 

     while ((read = inputStream.read(bytes)) != -1) { 
      outputStream.write(bytes, 0, read); 
     } 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    return "index"; 
}

Uploded文件：


public class UploadedFile { 

    private MultipartFile file; 

    public MultipartFile getFile() { 
     return file; 
    } 

    public void setFile(MultipartFile file) { 
     System.out.println("setFile"); 
     this.file = file; 
    } 
}

網頁：

<form:form method="post" action="uploadAvatar" commandName="avatar" enctype="multipart/form-data"> 
    <table> 
     <tr> 
      <td>Upload File: </td> 
      <td><input type="file" path="file" /> 
     </tr> 
     <tr> 
      <td> </td> 
      <td><input type="submit" value="Upload" /> 
      </td> 
      <td> </td> 
     </tr> 
    </table> 
</form:form>

登錄：


SEVERE: Servlet.service() for servlet [mvc-dispatcher] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause 
java.lang.NullPointerException 
    at com.petrez.controller.FileUploader.uploadAvatar(FileUploader.java:21) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) 
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:440) 
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:428) 
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) 
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) 
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) 
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) 
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) 
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) 
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) 
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) 
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) 
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) 
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343) 
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) 
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 
    at java.lang.Thread.run(Thread.java:722)

我在春天是新的。所以，請幫助我。

來源

2014-01-06 Petr Shypila

而不是把一個'ModelAttribute'參數，請嘗試直接把一個'MultipartFile'參數。 –

您是否在庫中添加了commons-io和commons-fileupload？當使用CommonsMultipartResolver時，你需要在你的類路徑中有commons-fileupload.jar – gipinani

@SotiriosDelimanolis謝謝，但它沒有幫助。 –

您在<input>標記上使用path屬性 - 在使用Spring的<form:input>時有效，但不適用於標準HTML <input>。更改path到name

<input type="file" name="file" />

來源

2014-01-06 21:27:04

+1好眼睛。請求中必須存在帶有相應'name'的請求參數。 –

非常感謝！你幫了我：） –

使用MultipartResolver進行Spring文件上傳。空指針異常

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