用httpclient4.3 post方式推送文件到服务端  
准备：httpclient-4.3.3.jar；httpcore-4.3.2.jar；httpmime-4.3.3.jar
/**

 * 上传文件

 * @throws  ParseException

 * @throws  IOException

 */

publicstaticvoidpostFile()throwsParseException, IOException{

    CloseableHttpClient httpClient = HttpClients.createDefault();

    try{

        // 要上传的文件的路径

        String filePath =newString("F:/pic/001.jpg");

        // 把一个普通参数和文件上传给下面这个地址 是一个servlet

        HttpPost httpPost =newHttpPost(

                "http://localhost:8080/xxx/xxx.action");

        // 把文件转换成流对象FileBody

        File file =newFile(filePath);

        FileBody bin =newFileBody(file);

        StringBody uploadFileName =newStringBody(

                "把我修改成文件名称", ContentType.create(

                        "text/plain", Consts.UTF_8));

        //以浏览器兼容模式运行，防止文件名乱码。

           HttpEntity reqEntity = MultipartEntityBuilder.create().setMode(HttpMultipartMode.BROWSER_COMPATIBLE)

                .addPart("uploadFile", bin)//uploadFile对应服务端类的同名属性<File类型>

                .addPart("uploadFileName", uploadFileName)//uploadFileName对应服务端类的同名属性<String类型>

                .setCharset(CharsetUtils.get("UTF-8")).build();

        httpPost.setEntity(reqEntity);

        System.out.println("发起请求的页面地址 "+ httpPost.getRequestLine());

        // 发起请求 并返回请求的响应

        CloseableHttpResponse response = httpClient.execute(httpPost);

        try{

            System.out.println("----------------------------------------");

            // 打印响应状态

            System.out.println(response.getStatusLine());

            // 获取响应对象

            HttpEntity resEntity = response.getEntity();

            if(resEntity !=null) {

                // 打印响应长度

                System.out.println("Response content length: "

                        + resEntity.getContentLength());

                // 打印响应内容

                System.out.println(EntityUtils.toString(resEntity,

                        Charset.forName("UTF-8")));

            }

            // 销毁

            EntityUtils.consume(resEntity);

        }finally{

            response.close();

        }

    }finally{

        httpClient.close();

    }

}

 /**

 * 下载文件

 * @param  url

 * @param  destFileName   xxx.jpg/xxx.png/xxx.txt

 * @throws  ClientProtocolException

 * @throws IOException

 */

publicstaticvoidgetFile(String url, String destFileName)

        throwsClientProtocolException, IOException {

    // 生成一个httpclient对象

    CloseableHttpClient httpclient = HttpClients.createDefault();

    HttpGet httpget =newHttpGet(url);

    HttpResponse response = httpclient.execute(httpget);

    HttpEntity entity = response.getEntity();

    InputStream in = entity.getContent();

    File file =newFile(destFileName);

    try{

        FileOutputStream fout =newFileOutputStream(file);

        intl = -1;

        byte[] tmp =newbyte[1024];

        while((l = in.read(tmp)) != -1) {

            fout.write(tmp,0, l);

            // 注意这里如果用OutputStream.write(buff)的话，图片会失真，大家可以试试

        }

        fout.flush();

        fout.close();

    }finally{

        // 关闭低层流。

        in.close();

    }

    httpclient.close();

}