Servlet3.x 實現上傳文件 原

1.web.xml必須是3.0以上版本

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
	version="3.1">
</web-app>

2.在web.xml中的spring 的DispatcherServlet配置multipart-config

<servlet>
		<servlet-name>spring</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:webApplicationContext.xml</param-value>
		</init-param>
		<load-on-startup>1</load-on-startup>
	        <multipart-config>
			<max-file-size>1000000</max-file-size>
		</multipart-config>
	</servlet>

	<servlet-mapping>
		<servlet-name>spring</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>

3.spring上下文中配置StandardServletMultipartResolver

       <!-- Using a MultipartResolver with Servlet 3.0 -->
	<bean id="multipartResolver"
		class="org.springframework.web.multipart.support.StandardServletMultipartResolver">
	</bean>

4.Controller中實現

@RequestMapping(value = "", method = RequestMethod.POST)
@ResponseBody
public ResponseEntity<?> uploadFile(HttpServletRequest request) {
    Part part = request.getPart(inputName);
    InputStream in = part.getInputStream();
}

5.參考
5.1 Using a MultipartResolver with Servlet 3.0
5.2 The getParts and getPart Methods
6.相關異常
6.1異常信息：

java.lang.IllegalStateException: Unable to process parts as no multi-part configuration has been provided
	at org.apache.catalina.connector.Request.parseParts(Request.java:2680)
	at org.apache.catalina.connector.Request.getParts(Request.java:2647)
	at org.apache.catalina.connector.RequestFacade.getParts(RequestFacade.java:1083)
	at org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.parseRequest(StandardMultipartHttpServletRequest.java:92)
	at org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.<init>(StandardMultipartHttpServletRequest.java:85)
	at org.springframework.web.multipart.support.StandardServletMultipartResolver.resolveMultipart(StandardServletMultipartResolver.java:76)
	at org.springframework.web.servlet.DispatcherServlet.checkMultipart(DispatcherServlet.java:1091)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:930)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	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:212)
	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:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

6.2原因
servlet沒有配置multipart-config>

 <multipart-config>
    <max-file-size>1000000</max-file-size>
</multipart-config>