我正在尝试编写一个简单的 WebApp 将文件上传到 MongoDB 数据库中。我可以上传文档的主题和对象的日期（作为字符串数据类型）。我现在正在尝试将实际文件上传到 MongoDB，但事实证明这很困难。我尝试了 MultipartFile，但它不会加载文件。然后我尝试将字符串获取到文件路径并产生空指针异常（可能是因为字符串路径指向本地资源，而不是服务器上）。
如何使用 webapp 将文件上传到 MongoDB？我为所有代码道歉，但我不知道我应该发布多少。
错误：
java.lang.NullPointerException
at java.io.File.<init>(File.java:251)
at com.jcdc.domain.FileUpload.setFile(FileUpload.java:34)
at com.jcdc.controller.DocumentController.create(DocumentController.java:43)
at com.jcdc.controller.DocumentController$$FastClassByCGLIB$$f5f3eaff.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:689)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.aop.interceptor.CustomizableTraceInterceptor.invokeUnderTrace(CustomizableTraceInterceptor.java:256)
at org.springframework.aop.interceptor.AbstractTraceInterceptor.invoke(AbstractTraceInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
at com.jcdc.controller.DocumentController$$EnhancerByCGLIB$$6b66bfcf.create(<generated>)
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:606)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:212)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
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.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:472)
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:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
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:724)
这是我的文件：
领域层
文件上传.java
package com.jcdc.domain;
import org.springframework.data.annotation.Id;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
@org.springframework.data.mongodb.core.mapping.Document
public class FileUpload {
@Id
private String id;
MultipartFile file;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public MultipartFile getFile() {
return file;
}
public void setFile(String filePath) {
File f = new File(filePath);
this.file = (MultipartFile) f;
}
}
文档.java
package com.jcdc.domain;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.DBRef;
@org.springframework.data.mongodb.core.mapping.Document
public class Document {
@Id
private String id;
private String subject;
private String date;
@DBRef
private FileUpload file;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public FileUpload getFile() {
return file;
}
public void setFile(FileUpload file) {
this.file = file;
}
}
控制器层
文档控制器.java
package com.jcdc.controller;
import com.jcdc.domain.Document;
import com.jcdc.domain.FileUpload;
import com.jcdc.dto.DocumentListDto;
import com.jcdc.service.DocumentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
@Controller
@RequestMapping("/documents")
public class DocumentController {
@Autowired
private DocumentService service;
@RequestMapping
public String getDocumentsPage() {
return "documents";
}
//...
@RequestMapping(value="/create", method=RequestMethod.POST)
public @ResponseBody Document create(
@RequestParam String subject,
@RequestParam String date, String filepath) {
FileUpload newFile = new FileUpload();
newFile.setFile(filepath);
System.out.println(filepath);
System.out.println(newFile.getFile().toString());
Document newDocument = new Document();
newDocument.setFile(newFile);
newDocument.setSubject(subject);
newDocument.setDate(date);
return service.create(newDocument);
}
}
查看图层
文档.jsp
<div id='newForm'>
<form>
<fieldset>
<legend>Create New Record</legend>
<label for='newSubject'>Subject</label><input type='text' id='newSubject'/><br/>
<label for='newDate'>Date</label><input type='date' id='newDate'/><br/>
<label for='newFile'>File</label><input type='file' id='newFile'/><br/>
</fieldset>
<input type='button' value='Close' id='closeNewForm' />
<input type='submit' value='Submit'/>
</form>
自定义.js
function submitNewRecord() {
$.post(urlHolder.add, {
subject: $('#newSubject').val(),
date: $('#newDate').val(),
file: $('#newFile').val()
},
function(response) {
if (response != null) {
loadTable();
toggleForms('hide');
toggleCrudButtons('show');
alert('Success! Record has been added.');
} else {
alert('Failure! An error has occurred!');
}
}
);
}