老古董volley，相比retrofit等新秀來說學(xué)習(xí)曲線平緩，所以項目為了快速上線就選擇了它。有一個需求是通過一個請求上傳多張圖片到服務(wù)器，很快就到gayhub上找到了別人造好的輪子，代碼如下：

/**
 * Custom request to make multipart header and upload file.
 *
 * Sketch Project Studio
 * Created by Angga on 27/04/2016 12.05.
 */
public class VolleyMultipartRequest extends Request<NetworkResponse> {
    private final String twoHyphens = "--";
    private final String lineEnd = "\r\n";
    private final String boundary = "apiclient-" + System.currentTimeMillis();

    private Response.Listener<NetworkResponse> mListener;
    private Response.ErrorListener mErrorListener;
    private Map<String, String> mHeaders;

    /**
     * Default constructor with predefined header and post method.
     *
     * @param url           request destination
     * @param headers       predefined custom header
     * @param listener      on success achieved 200 code from request
     * @param errorListener on error http or library timeout
     */
    public VolleyMultipartRequest(String url, Map<String, String> headers,
                                  Response.Listener<NetworkResponse> listener,
                                  Response.ErrorListener errorListener) {
        super(Method.POST, url, errorListener);
        this.mListener = listener;
        this.mErrorListener = errorListener;
        this.mHeaders = headers;
    }

    /**
     * Constructor with option method and default header configuration.
     *
     * @param method        method for now accept POST and GET only
     * @param url           request destination
     * @param listener      on success event handler
     * @param errorListener on error event handler
     */
    public VolleyMultipartRequest(int method, String url,
                                  Response.Listener<NetworkResponse> listener,
                                  Response.ErrorListener errorListener) {
        super(method, url, errorListener);
        this.mListener = listener;
        this.mErrorListener = errorListener;
    }

    ... ...

    @Override
    protected Response<NetworkResponse> parseNetworkResponse(NetworkResponse response) {
        try {
            return Response.success(
                    response,
                    HttpHeaderParser.parseCacheHeaders(response));
        } catch (Exception e) {
            return Response.error(new ParseError(e));
        }
    }

    @Override
    protected void deliverResponse(NetworkResponse response) {
        mListener.onResponse(response);
    }

    @Override
    public void deliverError(VolleyError error) {
        mErrorListener.onErrorResponse(error);
    }

    /**
     * Parse string map into data output stream by key and value.
     *
     * @param dataOutputStream data output stream handle string parsing
     * @param params           string inputs collection
     * @param encoding         encode the inputs, default UTF-8
     * @throws IOException
     */
    private void textParse(DataOutputStream dataOutputStream, Map<String, String> params, String encoding) throws IOException {
        try {
            for (Map.Entry<String, String> entry : params.entrySet()) {
                buildTextPart(dataOutputStream, entry.getKey(), entry.getValue());
            }
        } catch (UnsupportedEncodingException uee) {
            throw new RuntimeException("Encoding not supported: " + encoding, uee);
        }
    }

    /**
     * Parse data into data output stream.
     *
     * @param dataOutputStream data output stream handle file attachment
     * @param data             loop through data
     * @throws IOException
     */
    private void dataParse(DataOutputStream dataOutputStream, Map<String, DataPart> data) throws IOException {
        for (Map.Entry<String, DataPart> entry : data.entrySet()) {
            buildDataPart(dataOutputStream, entry.getValue(), entry.getKey());
        }
    }

    /**
     * Write string data into header and data output stream.
     *
     * @param dataOutputStream data output stream handle string parsing
     * @param parameterName    name of input
     * @param parameterValue   value of input
     * @throws IOException
     */
    private void buildTextPart(DataOutputStream dataOutputStream, String parameterName, String parameterValue) throws IOException {
        dataOutputStream.writeBytes(twoHyphens + boundary + lineEnd);
        dataOutputStream.writeBytes("Content-Disposition: form-data; name=\"" + parameterName + "\"" + lineEnd);
        //dataOutputStream.writeBytes("Content-Type: text/plain; charset=UTF-8" + lineEnd);
        dataOutputStream.writeBytes(lineEnd);
        dataOutputStream.writeBytes(parameterValue + lineEnd);
    }

    ... ...
}

整個類太長只截取一部分，使用中遇到的問題是，當上傳文件的時候同時帶有其他參數(shù)而且參數(shù)中有中文字符串的時候，到了服務(wù)器就是亂碼而英文沒有問題。最初懷疑是accepted這個header設(shè)置的問題，改成utf-8仍然有問題，如果參數(shù)用utf-8先encode一遍則服務(wù)器也要做相應(yīng)的修改，先decode再入庫。因為iOS端沒問題，所以沒有考慮后一個方案。

其他接口使用中文參數(shù)是沒問題的，所以單獨考慮這個上傳request的代碼。在處理函數(shù)的時候，這個類使用的是

dataOutputStream.writeBytes(parameterValue + lineEnd);

直接writeBytes，因為java里邊的字符是雙字節(jié)的，所以如果用這個參數(shù)的話高8位會被丟棄。改為如下語句解決問題：

dataOutputStream.write(parameterValue.getBytes());
dataOutputStream.writeBytes(lineEnd);

gayhub上搜索發(fā)現(xiàn)很多庫直接用了這個文件，可能只是一直使用英文參數(shù)沒有出現(xiàn)問題，相當于埋了一顆雷。如果想要該類的完整代碼，直接搜索VolleyMultipartRequest.java應(yīng)該能搜很多。