How do I access the returned value from a Web API Method in Android?

问题

After being confused about how to do so (as can be seen here and here, I am now successfully connecting to my server app and the appropriate RESTful method with this code:

public void onFetchBtnClicked(View v){
    if(v.getId() == R.id.FetchBtn){
        Toast.makeText(getApplicationContext(), "You mashed the button, dude.", Toast.LENGTH_SHORT).show();
    new CallAPI().execute("http://10.0.2.2:28642/api/Departments/GetCount?serialNum=4242");
    }
}

public static class CallAPI extends AsyncTask<String, String, String> {

    @Override
    protected String doInBackground(String... params) {

        String urlString=params[0]; // URL to call
        String resultToDisplay = "";
        InputStream in = null;

        // HTTP Get
        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            in = new BufferedInputStream(urlConnection.getInputStream());
        } catch (Exception e ) {
            System.out.println(e.getMessage());
            return e.getMessage();
        }
        return resultToDisplay;

    }

    protected void onPostExecute(String result) {
        Log.i("FromOnPostExecute", result);
    }

} // end CallAPI

I realize I need to assign something (other than an empty string at initialization) to resultToDisplay, but what? What part of "in" do I need to access/covert to a string?

UPDATE

The "manual" way is working for me, but the fancypants apache io utils "not so much" (well, it compiles...). This is my code:

try {
    URL url = new URL(urlString);
    HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
    in = new BufferedInputStream(urlConnection.getInputStream());
    resultToDisplay = getStringFromInputStream(in);
    total = IOUtils.toString(in);

resultToDisplay's assignment works (I get, "18"). total's assignment does not (I get, "").

Note: The "getStringFromInputStream()" method is from Raghunandan's link.

UPDATE 2

This works just dandy (using WIllJBD's idea to use apache commons' IOUtils):

new CallWebAPI().execute("http://10.0.2.2:28642/api/Departments/GetCount?serialNum=4242");
. . .
private class CallWebAPI extends AsyncTask<String, String, String> {

    @Override
    protected String doInBackground(String... params) {

        String urlString=params[0]; // URL to call
        String result = "";

        // HTTP Get
        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection =  
                (HttpURLConnection)url.openConnection();
            InputStream inputStream = urlConnection.getInputStream();
            if (null != inputStream)
                result= IOUtils.toString(inputStream);
        } catch (Exception e ) {
            System.out.println(e.getMessage());
            return e.getMessage();
        }
        return result;
    }

    @Override
    protected void onPostExecute(String result) {
        Log.i("RenameTheWashingtonFootballTeamTheRedskinPeanuts", result);
    }
}

...and so apparently it is not necessary to add anything like "compile files('libs/commons-io-2.4.jar')" to the dependencies section of build.gradle, as seemingly was at least necessary at one time, according to this. If anybody can verify such a[m,pp]endments to build.gradle are no longer needed, I'd be gradleful.

UPDATE 4

I just noticed that I inadvertently removed the "@Override" from the onPostExecute() method, but it made no difference - it worked fine without it, and it works fine once I restored it. So what's the advantage of [not] having it - is it just superfluous fluff?

回答1:

why not use something like IOUtils?

InputStream inputStream = urlConnection.getInputStream();
if (inputStream != null)
    String content = IOUtils.toString(inputStream);

http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/IOUtils.html

now you can parse the string into Json or XML, using one of many libraries.

来源：https://stackoverflow.com/questions/22818292/how-do-i-access-the-returned-value-from-a-web-api-method-in-android

标签

java

android

android-asynctask

http-get

bufferedinputstream