續上文,
場景:
不上傳文件提交表單。
簡述一下:表單請求的兩種方式
- 同步提交
- 異步提交
筆者之前寫過的測試Demo:
HTML:
<form action="upload.do" method="post" enctype="multipart/form-data">
<input type="file" name="fileName" />
<input type="submit" value="Submit" />
</form>
控制器:
@RequestMapping(value = "/upload.do", method = RequestMethod.POST)
@ResponseBody
public Map<String, Object> add(@RequestParam(value="fileName") MultipartFile file){
//...
return null;
}
錯誤信息:
11:03:07.147 [http-nio-8080-exec-4] DEBUG o.s.w.s.m.a.AnnotationMethodHandlerExceptionResolver - Resolving exception from handler [com.xFee.serverAdmin.controller.ApkInfoController@25a5db]: org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'org.springframework.web.multipart.MultipartFile'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.springframework.web.multipart.MultipartFile]: no matching editors or conversion strategy found
11:03:07.147 [http-nio-8080-exec-4] DEBUG o.s.w.s.m.a.ResponseStatusExceptionResolver - Resolving exception from handler [com.xFee.serverAdmin.controller.ApkInfoController@25a5db]: org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'org.springframework.web.multipart.MultipartFile'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.springframework.web.multipart.MultipartFile]: no matching editors or conversion strategy found
11:03:07.147 [http-nio-8080-exec-4] DEBUG o.s.w.s.m.s.DefaultHandlerExceptionResolver - Resolving exception from handler [com.xFee.serverAdmin.controller.ApkInfoController@25a5db]: org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'org.springframework.web.multipart.MultipartFile'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.springframework.web.multipart.MultipartFile]: no matching editors or conversion strategy found
11:03:07.147 [http-nio-8080-exec-4] DEBUG o.s.web.servlet.DispatcherServlet - Null ModelAndView returned to DispatcherServlet with name 'springServlet': assuming HandlerAdapter completed request handling
11:03:07.147 [http-nio-8080-exec-4] DEBUG o.s.web.servlet.DispatcherServlet - Successfully completed request
筆者忽略了,在同步提交的時候,Spring把空上傳是做null來處理的,而在異步提交的時候,Spring把文件域的值當作空字符串看待的。在Spring做請求轉換的時候(request
–>MultipartHttpServletRequest
)底層的TypeConverter
接口實現對null
和""
是做了不同操作的。源碼就不貼了,有興趣的夥伴可以自行從:org.springframework.web.multipart.commons.CommonsMultipartResolver
這個類跟下去,就會發現差異。
解決方案
在配置文件中加入以下配置:
<bean id="conversionService"
class="org.springframework.context.support.ConversionServiceFactoryBean">
<property name="converters">
<list>
<bean class="com.xFee.serverAdmin.utils.SpringMVCFileConverter"></bean>
</list>
</property>
</bean>
<mvc:annotation-driven conversion-service="conversionService" />
然後在list下的bean節點的class屬性的路徑下創建一個SpringMVCFileConverter
:
public class SpringMVCFileConverter implements Converter<String, MultipartFile> {
public SpringMVCFileConverter() {
super();
}
@Override
public MultipartFile convert(String source) {
return null;
}
}
注:注意在引入上面配置文件的時候不要忘記引入其定義及約束文件。
學生淺薄,望衆師指點
wengang.liu