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 map = new HashMap();
		// 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 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);
}

其中，renderJson的代码见：

/**
 * 输出文本内容到页面上
 * @param text 文本内容
 * @param contentType 返回类型
 */
private void render(HttpServletResponse response, String text, String contentType) {
	if (response != null) {
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		response.setContentType(contentType);
		PrintWriter pWriter = null;
		try {
			pWriter = response.getWriter();
			pWriter.write(text);
			pWriter.flush();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (pWriter != null) {
				pWriter.close();
			}
		}
	}
}

/**
 * 输出普通文本到页面
 * @param text 普通文本
 */
protected void renderText(HttpServletResponse response, String text) {
	this.render(response, text, "text/plain;charset=UTF-8");
}

/**
 * 输出Html格式的文本到页面
 * @param text Html文本内容
 */
protected void renderHtml(HttpServletResponse response, String html) {
	this.render(response, html, "text/html;charset=UTF-8");
}

/**
 * 输出Json格式的文本到页面
 * @param json Json文本内容
 */
protected void renderJson(HttpServletResponse response, String json) {
	this.render(response, json, "text/json;charset=UTF-8");
}

/**
 * 输出Json格式的文本到页面
 * @param obj 待转换对象
 */
protected void renderJson(HttpServletResponse response, Object obj) {
	Gson gson = new Gson();
	String json = gson.toJson(obj);
	this.renderJson(response, json);
}

/**
 * 输出XML格式的文本到页面
 * @param xml XML文本内容
 */
protected void renderXML(HttpServletResponse response, String xml) {
	this.render(response, xml, "text/xml;charset=UTF-8");
}

/**
 * 输出结果“success”到页面
 */
protected void renderSuccess(HttpServletResponse response) {
	this.renderText(response, SUCCESS);
}

/**
 * 输出结果“error”到页面
 */
protected void renderError(HttpServletResponse response) {
	this.renderText(response, ERROR);
}