POST傳送與接收 aspx.cs ashx java

出處

[ASP.NET]在server端post資料到.ashx

前言
前陣子同事問我一個問題，要怎麼在server端post資料給遠端的.ashx。突然間我還真不知道怎麼做，因為通常都是在client端用ajax呼叫.ashx，如果是網站外的服務，通常都是Web service或WCF，.ashx還真沒碰到過。

所以survey了一下，寫了個小小Sample Code，當個memo。

需求
在server端post資料到.ashx，.ashx處理完後，接收.ashx的response。

範例
.aspx.cs

    protected void Button1_Click(object sender, EventArgs e)
    {

        var url = "http://localhost:13488/serverPostAshx/MyHandler.ashx";
        string uri = string.Format("{0}?who={1}", url, "joey");

        WebRequest request = WebRequest.Create(uri);
        request.Method = "POST";

        //加上"data="，讓server端可以透過Request.Form["data"]讀取
        string postData = "data={a:1, b:2, c:[3,4]}";

        byte[] byteArray = Encoding.UTF8.GetBytes(postData);

        request.ContentType = "application/x-www-form-urlencoded";

        // Set the ContentLength property of the WebRequest.
        request.ContentLength = byteArray.Length;

        // Get the request stream.
        using (Stream dataStream = request.GetRequestStream())
        {
            // Write the data to the request stream.
            dataStream.Write(byteArray, 0, byteArray.Length);
        }

        // Get the response.      
        using (WebResponse response = request.GetResponse())
        {
            using (Stream dataStream = response.GetResponseStream())
            {
                using (StreamReader reader = new StreamReader(dataStream))
                {
                    string responseFromServer = reader.ReadToEnd();
                    this.Button1.Text = responseFromServer;
                }
            }
        }
    }

.ashx

public class MyHandler : IHttpHandler
{

    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "text/plain";
        //Get QueryString
        var whom = context.Request.QueryString["who"];

        //取得整個Request傳過來的InputStream資料
        //var result = GetFromInputStream(context);

        //取得整個form資料
        //var result = HttpUtility.UrlDecode(context.Request.Form.ToString());

        var result = HttpUtility.UrlDecode(context.Request.Form["data"]);
        context.Response.Write(string.Format("{0} {1}", whom, result));
    }

    private static string GetFromInputStream(HttpContext context)
    {
        var reader = new System.IO.StreamReader(context.Request.InputStream);
        var result = reader.ReadToEnd();

        return result;
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }

}

說明

1. 使用WebRequest，Method屬性使用Post。
2. 將要post的資料，assign到WebRequest的InputStream這個屬性。
3. 在.ashx中，就可以透過context.Request.InputStream來取得Request post過來的資料。
4. 透過Encoding.UTF8.GetString就可以將InputStream還原成原本的字串。（可能是序列化後的字串）
5. 若有經過序列化(xml or json)可以將字串反序列化後，操作物件。
6. .aspx透過Request的GetResponse()，可以取得.ashx的回應。

結果畫面

1. 按按鈕前 
   
2. 按按鈕後 
   

結論
因為太少碰到這樣的需求了，所以memo一下，順便練習一下WebRequest的用法。如果大家有更好的建議作法，麻煩請不吝告知，謝謝。

參考

1. HttpRequest.InputStream 屬性
2. WebRequest.GetRequestStream 方法

Source Code : serverPostAshx.zip

勘誤1：感謝同事的提醒，送Request的方式一樣，只需要在post的data加上Form的Key。接著在server端就能透過Request.Form取得data的資料，經過UrlDecode後就是原本的資料。程式碼已經同步修改了，感謝提醒。

勘誤2：感謝黑大提醒，將原本讀取InputStream的部分，改為直接用StreamReader的ReadToEnd()，更為簡潔。程式碼已經同步修改了，感謝提醒。

JAVA部分

private static final String USER_AGENT = "Mozilla/5.0";
private static final String GET_URL = "http://網址/tt.ashx";

private static final String POST_URL = "http://網址/tt.ashx";
private static final String POST_PARAMScc = "?gg=ww";private static final String POST_PARAMS ="data="+"資料"

//傳送資料private boolean sendPOST()
{
    String urlData = null;    URL url = null;    HttpURLConnection httpUrlConnection = null;    try {
        url = new URL(POST_URL+POST_PARAMScc);        URLConnection rulConnection = url.openConnection();        httpUrlConnection = (HttpURLConnection) rulConnection;        httpUrlConnection.setDoOutput(true);        httpUrlConnection.setDoInput(true);        httpUrlConnection.setUseCaches(false);        //httpUrlConnection.setRequestProperty("Content-type", "application/x-java-serialized-object");        httpUrlConnection.setRequestProperty("Content-type", "application/x-www-form-urlencoded");        //httpUrlConnection.setRequestMethod("GET");        httpUrlConnection.setRequestMethod("POST");
        // For POST only - START        OutputStream os = httpUrlConnection.getOutputStream();        os.write(POST_PARAMS.getBytes());        os.flush();        os.close();        // For POST only - END
        int responseCode=httpUrlConnection.getResponseCode();        String decodedString;        if (responseCode == HttpURLConnection.HTTP_OK)
        {
            BufferedReader in = new BufferedReader(new InputStreamReader(
                    httpUrlConnection.getInputStream()));            while ((decodedString = in.readLine()) != null) {
                urlData += decodedString;            }
            in.close();        }

        httpUrlConnection.disconnect();
    } catch (MalformedURLException e) {
        e.printStackTrace();    } catch (IOException e) {
        e.printStackTrace();    }
    catch (Exception e) {
        e.printStackTrace();    }

    if(httpUrlConnection != null)
    {
        httpUrlConnection.disconnect();    }
    //return false;


}

記得加上

<uses-permission android:name="android.permission.INTERNET" /><uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />