大家好，
在整天摆弄并找到互联网解决方案后，我仍然无法解决这个问题。所以我需要宇宙中那些聪明的大脑来帮助我。 :-) 我正在尝试使用泽西Restful服务将文件上传到服务器。虽然我想这样做，我得到空指针异常。任何指针都将受到高度赞赏。
以下是我的环境配置：
Jersey Jars：
下面是我的web.xml，其中包含我的restl服务的url模式。
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>mixtri</display-name>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<display-name>mixtri</display-name>
<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<!-- Register resources and providers under com.vogella.jersey.first package. -->
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>com.mixtri.uploader</param-value>
</init-param>
<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>org.glassfish.jersey.filter.LoggingFilter;org.glassfish.jersey.media.multipart.MultiPartFeature</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/*</url-pattern>
</servlet-mapping>
</web-app>
下面是一个简单的HTML表单，分别有2个按钮浏览和上传：
<div class="container">
<form action="/mixtri/rest/upload" method="post" enctype="multipart/form-data">
<input type="file" value="browse" name="file">
<input type="submit" value="upload">
</form>
</div>
下面是我的资源类，它有2个输入参数FormDataContentDisposition和InputStream。
package com.mixtri.uploader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import org.glassfish.jersey.media.multipart.FormDataContentDisposition;
import org.glassfish.jersey.media.multipart.FormDataParam;
@Path("/")
public class UploadFileService {
@POST
@Path("/upload")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response uploadFile(
@FormDataParam("file") InputStream uploadedInputStream,
@FormDataParam("file") FormDataContentDisposition fileDetail) {
// save it
saveToDisk(uploadedInputStream, fileDetail);
String output = "D:/uploaded/" + fileDetail.getName();
return Response.status(200).entity(output).build();
//return "File Uploaded Successfully";
}
// save uploaded file to new location
private void saveToDisk(InputStream uploadedInputStream,
FormDataContentDisposition fileDetail) {
String uploadedFileLocation = "D:/uploaded/" + fileDetail.getName();
try {
OutputStream out = new FileOutputStream(new File(
uploadedFileLocation));
int read = 0;
byte[] bytes = new byte[1024];
out = new FileOutputStream(new File(uploadedFileLocation));
while ((read = uploadedInputStream.read(bytes)) != -1) {
out.write(bytes, 0, read);
}
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
下面是stacktrace，它包含有关在初始几行中发送到服务器的请求的信息，然后在该空指针异常发生之后。我真的陷入了困境，无法前进
Jul 01, 2015 6:58:49 PM org.glassfish.jersey.filter.LoggingFilter log
INFO: 3 * Server has received a request on thread http-nio-8080-exec-8
POST http://localhost:8080/mixtri/rest/upload
accept: text/html, */*; q=0.01
accept-encoding: gzip, deflate
accept-language: en-US,en;q=0.8
connection: keep-alive
content-length: 0
cookie: JSESSIONID=CA18D302131AAB8DD4A77EFF95DD4A45
host: localhost:8080
origin: http://localhost:8080
referer: http://localhost:8080/mixtri/sample.jsp
user-agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.130 Safari/537.36
x-requested-with: XMLHttpRequest
Jul 01, 2015 6:58:49 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Jersey REST Service] in context with path [/mixtri] threw exception [java.lang.NullPointerException] with root cause
java.lang.NullPointerException
at org.glassfish.jersey.media.multipart.internal.FormDataParamValueFactoryProvider$FormDataParamValueFactory.provide(FormDataParamValueFactoryProvider.java:205)
at org.glassfish.jersey.server.spi.internal.ParameterValueHelper.getParameterValues(ParameterValueHelper.java:81)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$AbstractMethodParamInvoker.getParamValues(JavaResourceMethodDispatcherProvider.java:121)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:152)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:104)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:384)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:342)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:101)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:297)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:254)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1030)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:373)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:381)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:344)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:221)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
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