SpringMVC实现上传和下载

[From] http://my.oschina.net/u/1394615/blog/311307

package com.pk.web.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;

/**
* Created by Administrator on 2014/9/5.
*/
@Controller
@RequestMapping("file")
public class UploadController {
@RequestMapping("/upload.do")
public String upload(HttpServletRequest request,
HttpServletResponse response) throws IOException {
// 这里我用到了jar包
CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(
request.getSession().getServletContext());
if (multipartResolver.isMultipart(request)) {
MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;

Iterator<String> iter = multiRequest.getFileNames();
while (iter.hasNext()) {
MultipartFile file = multiRequest.getFile((String) iter.next());
if (file != null) {
String fileName = file.getOriginalFilename();

String path1 = Thread.currentThread()
.getContextClassLoader().getResource("").getPath()
+ "download" + File.separator;

// 下面的加的日期是为了防止上传的名字一样
String path = path1
+ new SimpleDateFormat("yyyyMMddHHmmss")
.format(new Date()) + fileName;

File localFile = new File(path);

file.transferTo(localFile);
}

}

}
return "uploadSuccess";

}
@RequestMapping("/toUpload.do")
public String toUpload() {
return "upload";
}

@RequestMapping("/download")
public String download(String fileName, HttpServletRequest request,
HttpServletResponse response) {
response.setCharacterEncoding("utf-8");
response.setContentType("multipart/form-data");
response.setHeader("Content-Disposition", "attachment;fileName="
+ fileName);
try {
String path = Thread.currentThread().getContextClassLoader()
.getResource("").getPath()
+ "download";//这个download目录为啥建立在classes下的
InputStream inputStream = new FileInputStream(new File(path
+ File.separator + fileName));

OutputStream os = response.getOutputStream();
byte[] b = new byte[2048];
int length;
while ((length = inputStream.read(b)) > 0) {
os.write(b, 0, length);
}

// 这里主要关闭。
os.close();

inputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// 返回值要注意，要不然就出现下面这句错误！
//java+getOutputStream() has already been called for this response
return null;
}
}

还有 上传 配置文件注意

<!-- mvc注解驱动 -->

<mvc:annotation-driven/>

<!-- 扫描器已经有了上面这个mvc注解驱动的功能了，所有不需要了 -->

<context:component-scan base-package="com.pk.web.controller" />

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">

<property name="defaultEncoding" value="utf-8" />

<property name="maxUploadSize" value="104857600"/>

<property name="maxInMemorySize" value="4096"/>

</bean>

<!-- 前缀+ viewName +后缀 -->

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">

<!-- webroot到某一指定的文件夹的路径 -->

<property name="prefix" value="/WEB-INF/jsp/"></property>

<!-- 自己在你的 /WEB-INF/jsp下建立给jsp见面吧。或者该我上面的配置 -->

<!-- 视图名称的后缀 -->

<property name="suffix" value=".jsp"></property>

</bean>

这里是html 点击下载，这里就写死了（你可以修改成你自己放的文件）。可以修改的。

<a href="file/download.do?fileName=map.txt">下载1 </a><br />

下面这里是上传代码

<form action="file/upload.do" method="post" enctype="multipart/form-data">

选择文件<input type="file" name="file">

<input type="submit" value="上传">

</form>

web.xml 配置文件

<servlet>

<servlet-name>springmvc</servlet-name>

<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

<load-on-startup>1</load-on-startup>

</servlet>

<filter>

<filter-name>encodingFilter</filter-name>

<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

<init-param>

<param-name>encoding</param-name>

<param-value>UTF-8</param-value>

</init-param>

<init-param>

<param-name>forceEncoding</param-name>

<param-value>true</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>encodingFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<servlet-mapping>

<servlet-name>springmvc</servlet-name>

<!-- struts习惯使用/*，在springmvc不管用 -->

<url-pattern>*.do</url-pattern>

</servlet-mapping>

每个方法都返回的是一个ActionForward对象，而response是ActionForward对象参数，所以就会使response冲突！ 

所以处理上传的action返回null就可以了

最终我把action里的最后 “return SUCCESS ” 改成了 “return null ”   成功了 ！！！

jar 包在  oschina 这里不知道怎么上传过去给下载的。。同学们自己网上找吧！