Java 微信上传临时素材

微信小程序创建直播间，服务端上传临时素材，微信开放社区隐藏太深，不好找，记录一下，抄就行，亲测好用！！！

 

/**
* graphurl：上传临时素材微信接口地址，自己拼就行，file：客户端上传的文件
*/
public static String uploadFile(String graphurl,MultipartFile file) {
        String line = null;//接口返回的结果
        try {
            // 换行符
            final String newLine = "\r\n";
            final String boundaryPrefix = "--";
            // 定义数据分隔线
            String BOUNDARY = "========7d4a6d158c9";
            // 服务器的域名
            URL url = new URL(graphurl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            // 设置为POST情
            conn.setRequestMethod("POST");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            // 设置请求头参数
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("Charsert", "UTF-8");
            conn.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARY);
            conn.setRequestProperty("User-Agent","Mozilla/5.0 (iPhone; CPU iPhone OS 11_0 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Version/11.0 Mobile/15A372 Safari/604.1");
            OutputStream out = new DataOutputStream(conn.getOutputStream());

            // 上传文件
            StringBuilder sb = new StringBuilder();
            sb.append(boundaryPrefix);
            sb.append(BOUNDARY);
            sb.append(newLine);
            // 文件参数,photo参数名可以随意修改
            sb.append("Content-Disposition: form-data;name=\"image\";filename=\""
                    + file.getOriginalFilename() + "\"" + newLine);
            sb.append("Content-Type:application/octet-stream");
            // 参数头设置完以后需要两个换行，然后才是参数内容
            sb.append(newLine);
            sb.append(newLine);

            // 将参数头的数据写入到输出流中
            out.write(sb.toString().getBytes());

            // 读取文件数据
            out.write(file.getBytes());
            // 最后添加换行
            out.write(newLine.getBytes());

            // 定义最后数据分隔线，即--加上BOUNDARY再加上--。
            byte[] end_data = (newLine + boundaryPrefix + BOUNDARY
                    + boundaryPrefix + newLine).getBytes();
            // 写上结尾标识
            out.write(end_data);
            out.flush();
            out.close();
            // 定义BufferedReader输入流来读取URL的响应
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    conn.getInputStream()));
            while ((line = reader.readLine()) != null) {
                return line;
            }
        } catch (Exception e) {
            System.out.println("发送POST请求出现异常！" + e);
        }
        return line;
    }