我们已经在上一篇文章中讲解了把文件上传到远程服务器的一种方式:
java上传文件到远程服务器(一)---HttpURLConnection方式
本章来尝试使用HttpClient方式上传文件到远程服务器:
我们在之前的文章中已经在SpringMVC基础框架的基础上应用了BootStrap的后台框架，在此基础上记录HttpURLConnection上传文件到远程服务器。
应用bootstrap模板
基础项目源码下载地址为:
SpringMVC+Shiro+MongoDB+BootStrap基础框架
我们在基础项目中已经做好了首页index的访问。现在就在index.jsp页面和index的路由Controller上做修改，HttpClient上传文件到远程服务器。
客户端HttpClient上传文件到远程服务器的原理是通过构造参数模仿form提交文件的http请求，把文件提交到远程服务器的接收路由中。
index.jsp的代码为:
<%@ include file="./include/header.jsp"%> <div id="page-wrapper"> <div id="page-inner"> <div class="row"> <div class="col-md-12"> <h1 class="page-header"> HttpURLConnection <small>HttpURLConnection</small> </h1> </div> </div> <!-- /. ROW --> <form class="form-horizontal" name="upform" action="upload" method="post" enctype="multipart/form-data"> <div class="form-group"> <label for="sourceModule" class="col-sm-2 control-label">上传文件:</label> <div class="col-sm-10"> <input type="file" name="filename"/><br/> <input type="submit" value="提交" /><br/> </div> </div> </form> <!-- /. ROW --> </div> <!-- /. PAGE INNER --> </div> <!-- /. PAGE WRAPPER --> <%@ include file="./include/footer.jsp"%> <script type="text/javascript"> $(document).ready(function () { }); </script> </body> </html>需要httpclient的包，我这里使用的是httpclient4.3.3.jar和httpmime4.3。
如果使用的是maven则在pom.xml中添加:
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.3.3</version> </dependency>
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpmime</artifactId> <version>4.3</version> </dependency>
路由中upload方法接受form提交的file文件，并且上传到服务器:
IndexController.java代码如下:
package com.test.web.controller; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.servlet.http.HttpServletRequest; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.ParseException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.mime.MultipartEntity; import org.apache.http.entity.mime.content.FileBody; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.util.EntityUtils; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; /** * IndexController * * */ @Controller public class IndexController { private static final String FAR_SERVICE_DIR = "http://192.168.30.39:8080/receive";// 远程服务器接受文件的路由 private static final long yourMaxRequestSize = 10000000; @RequestMapping("/") public String index(Model model) throws IOException { return "/index"; } @RequestMapping("/upload") public String upload(HttpServletRequest request) throws Exception { // 判断enctype属性是否为multipart/form-data boolean isMultipart = ServletFileUpload.isMultipartContent(request); if (!isMultipart) throw new IllegalArgumentException( "上传内容不是有效的multipart/form-data类型."); // Create a factory for disk-based file items DiskFileItemFactory factory = new DiskFileItemFactory(); // Create a new file upload handler ServletFileUpload upload = new ServletFileUpload(factory); // 设置上传内容的大小限制（单位：字节） upload.setSizeMax(yourMaxRequestSize); // Parse the request List<?> items = upload.parseRequest(request); Iterator iter = items.iterator(); while (iter.hasNext()) { FileItem item = (FileItem) iter.next(); if (item.isFormField()) { // 如果是普通表单字段 String name = item.getFieldName(); String value = item.getString(); // ... } else { // 如果是文件字段 String fieldName = item.getFieldName(); String fileName = item.getName(); String contentType = item.getContentType(); boolean isInMemory = item.isInMemory(); long sizeInBytes = item.getSize(); // ... // 上传到远程服务器 HashMap<String, FileItem> files = new HashMap<String, FileItem>(); files.put(fileName, item); uploadToFarServiceByHttpClient(files); } } return "redirect:/"; } private void uploadToFarServiceByHttpClient(HashMap<String, FileItem> files) { HttpClient httpclient = new DefaultHttpClient(); try { HttpPost httppost = new HttpPost(FAR_SERVICE_DIR); MultipartEntity reqEntity = new MultipartEntity(); Iterator iter = files.entrySet().iterator(); while (iter.hasNext()) { Map.Entry entry = (Map.Entry) iter.next(); String key = (String) entry.getKey(); FileItem val = (FileItem) entry.getValue(); FileBody filebdody = new FileBody(inputstreamtofile( val.getInputStream(), key)); reqEntity.addPart(key, filebdody); } httppost.setEntity(reqEntity); HttpResponse response = httpclient.execute(httppost); int statusCode = response.getStatusLine().getStatusCode(); if (statusCode == HttpStatus.SC_OK) { System.out.println("服务器正常响应....."); HttpEntity resEntity = response.getEntity(); System.out.println(EntityUtils.toString(resEntity,"UTF-8"));// httpclient自带的工具类读取返回数据 EntityUtils.consume(resEntity); } } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { httpclient.getConnectionManager().shutdown(); } catch (Exception ignore) { } } } public File inputstreamtofile(InputStream ins, String filename) throws IOException { File file = new File(filename); OutputStream os = new FileOutputStream(file); int bytesRead = 0; byte[] buffer = new byte[8192]; while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) { os.write(buffer, 0, bytesRead); } os.close(); ins.close(); return file; } }