HttpClient4.5.2由Client客户端上传File文件流至Server服务端

应用场景：

java代码部分做文件资源同步。比如：应用系统将上传的文件备份或同步至文件服务器中。

代码位置

位于java client相关代码部分，将文件流通过httpClient工具发送网络请求到服务器上。

关键代码

将java.io.File对象添加到HttpEntity（org.apache.http.HttpEntity）对象中：

MultipartEntityBuilder mEntityBuilder = MultipartEntityBuilder.create();
mEntityBuilder.addBinaryBody("file", file);
httppost.setEntity(mEntityBuilder.build());

Client完整代码

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.ParseException;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.HttpClientUtils;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class FileClient {
/**
 * 将文件提交至文件服务器
 * @param file 文件对象
 * @return FileStatus 上传结果
 */
    public static String postFile(File file) {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String result = null;
        try {
            HttpPost httpPost = new HttpPost(ServerURL.URL_FILE_POST);
            MultipartEntityBuilder mEntityBuilder = MultipartEntityBuilder.create();
            mEntityBuilder.addBinaryBody("file", file);
            httpPost.setEntity(mEntityBuilder.build());
            response = httpclient.execute(httpPost);

            int statusCode = response.getStatusLine().getStatusCode();
            if (statusCode == HttpStatus.SC_OK) {
                HttpEntity resEntity = response.getEntity();
                result =EntityUtils.toString(resEntity);
                // 消耗掉response
                EntityUtils.consume(resEntity);
            }
        } catch (ParseException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            HttpClientUtils.closeQuietly(httpclient);
            HttpClientUtils.closeQuietly(response);
        }
        return result;
    }
}

Server代码

    /**
 * 上传文件
 * @param fileRequest
 */
@RequestMapping("/postFile")
public void postFile(HttpServletRequest request, HttpServletResponse response) {
        String result = "error";
        Map<String, Object> map = new HashMap<String, Object>();
// 创建一个通用的多部分解析器
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession()
                .getServletContext());
// 判断 request 是否有文件上传,即多部分请求
if (multipartResolver.isMultipart(request)) {
// 转换成多部分request
            MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;
// 取得request中的所有文件名
            Iterator<String> iter = multiRequest.getFileNames();
while (iter.hasNext()) {
// 取得上传文件
                MultipartFile multipartFile = multiRequest.getFile(iter.next());
if (multipartFile != null) {
// 取得当前上传文件的文件名称
                    String fileName = multipartFile.getOriginalFilename();
if (fileName.trim() != null && fileName.trim().length() > 0) {
                        CommonsMultipartFile cf = (CommonsMultipartFile) multipartFile;
                        DiskFileItem fi = (DiskFileItem) cf.getFileItem();
                        File tempFile = fi.getStoreLocation();
// 拿到文件，存储
                        ...
                        result = "success";
                    }
                }
            }
        }
    }
    map.put("result", result);
this.renderJson(response, map);
}