安卓用Volley做为请求框架，后台用SpringMvc，数据传输格式用Json。
请求的时候报一个错。

{
    "timestamp": 1498636645291,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
    "message": "Could not read document: Unrecognized token 'diffTime': was expecting ('true', 'false' or 'null')\n at [Source: java.io.PushbackInputStream@3a2ef3ba; line: 1, column: 10]; nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'diffTime': was expecting ('true', 'false' or 'null')\n at [Source: java.io.PushbackInputStream@3a2ef3ba; line: 1, column: 10]",
    "path": "/data/country/update"
}

挣扎许久后，发现是客户端Volley框架发出请求时的数据格式不对。

修改如下即可
在Volley框架中的Request.java类：

    private byte[] encodeParameters(Map<String, String> params, String paramsEncoding) {
//        StringBuilder encodedParams = new StringBuilder();
//        try {
//            for (Map.Entry<String, String> entry : params.entrySet()) {
//                encodedParams.append(URLEncoder.encode(entry.getKey(), paramsEncoding));
//                encodedParams.append('=');
//                encodedParams.append(URLEncoder.encode(entry.getValue(), paramsEncoding));
//                encodedParams.append('&');
//            }
//            return encodedParams.toString().getBytes(paramsEncoding);
//        } catch (UnsupportedEncodingException uee) {
//            throw new RuntimeException("Encoding not supported: " + paramsEncoding, uee);
//        }
        try{
            JSONObject jsonObject = new JSONObject(params);
            return jsonObject.toString().getBytes(paramsEncoding);
        } catch (UnsupportedEncodingException uee) {
            throw new RuntimeException("Encoding not supported: " + paramsEncoding, uee);
        }
    }

自己封装的继承Request<T>类，也需要补充点代码：
主要是getHeaders()、getBodyContentType()、parseNetworkResponse()方法

public class StringRequestJsonResult extends Request<JSONObject> {

    protected static final String PROTOCOL_CHARSET = "utf-8";

    private final Response.Listener<JSONObject> mListener;

    @Override
    public Map<String, String> getHeaders() throws AuthFailureError {
        Map<String,String> params = new HashMap<String, String>();
        params.put("Accept", "application/json");
        params.put("Content-Type", "application/json; charset=UTF-8");
        return params;
    }

    @Override
    public String getBodyContentType() {
        return "application/json; charset=" + getParamsEncoding();
    }

    /**
     * Creates a new request with the given method.
     *
     * @param method the request {@link Method} to use
     * @param url URL to fetch the string at
     * @param listener Listener to receive the String response
     * @param errorListener Error listener, or null to ignore errors
     */
    public StringRequestJsonResult(int method, String url, Response.Listener<JSONObject> listener,
                                   Response.ErrorListener errorListener) {
        super(method, url, errorListener);


        mListener = listener;
    }

    /**
     * Creates a new GET request.
     *
     * @param url URL to fetch the string at
     * @param listener Listener to receive the String response
     * @param errorListener Error listener, or null to ignore errors
     */
    public StringRequestJsonResult(String url, Response.Listener<JSONObject> listener, Response.ErrorListener errorListener) {
        this(Method.GET, url, listener, errorListener);
    }

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

    @Override
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
        try {
            String jsonString = new String(response.data,
                    HttpHeaderParser.parseCharset(response.headers, PROTOCOL_CHARSET));
            return Response.success(JSON.parseObject(jsonString),
                    HttpHeaderParser.parseCacheHeaders(response));
        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JSONException je) {
            return Response.error(new ParseError(je));
        }
    }
}

以上，完毕。