Question

我的Android应用程序中有一个小问题，我正在尝试将数组列表传递给asynctask以将一些数据发布到外部api。但是eclipse总是返回一个数据类型错误，我无法想象如何将params从活动传递给ASyncTask。请帮忙

  public void Login(View view){
    String usern = username.getText().toString();
    String pwd = password.getText().toString();

    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("username", usern));
    nameValuePairs.add(new BasicNameValuePair("password", pwd));                
    nameValuePairs.add(new BasicNameValuePair("external-login", "true"));

    if(isNetworkAvailable()){
        GetAxiomaCredentials axiomacredentials = new GetAxiomaCredentials();
        axiomacredentials.execute();
    }else{
        Toast.makeText(this, "Network is not available.", Toast.LENGTH_LONG).show();
    }
}

所以我可以传递nameValuePairs来作为参数执行但是我从AsyncTask Private类中得到一个错误的类型错误

  private class GetAxiomaCredentials extends AsyncTask<ArrayList<String>, Integer, String>{

    private static final String POST_URL = "http://192.168.0.105/index.php/r=rsite/heartbeat";

    @Override
    protected String doInBackground(ArrayList<String>... params) {
        int responseCode = -1;
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(POST_URL);
        try {
            // Add your data
            ArrayList<String> data = params[0];
            httppost.setEntity(new UrlEncodedFormEntity(data));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
        } catch (IOException e) {
            // TODO Auto-generated catch block
        }

        return "Code: " + responseCode;
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {

    }

    public void postData(String name, String email, String password,String mobile) {
        // Create a new HttpClient and Post Header

    }
}

我得到的eclipse编译错误就在这一行：

  ArrayList<String> data = params[0];
        httppost.setEntity(new UrlEncodedFormEntity(data));

那么如何解决此问题以将所有参数从活动中的Login操作传递给AsyncTask？感谢

Answer 1

将输入更改为doInBackground到ArrayList。这将删除强制转换异常。

private class GetAxiomaCredentials extends AsyncTask<Object, Integer, String>{
...

将ArrayList更改为Object

protected String doInBackground(Object... params) {
    int responseCode = -1;
    List<NameValuePair> data = (List<NameValuePair>) params[0];
    ...

然后当你调用execute时，传入nameValuePairs

if(isNetworkAvailable()){
    GetAxiomaCredentials axiomacredentials = new GetAxiomaCredentials();
    axiomacredentials.execute(nameValuePairs);

Answer 2

只需在GetAxiomaCredentials类中添加构造函数即可。构造函数应该将List对象作为参数，然后将其存储在类变量中，然后在doInBackground()中使用它。

有些事情如下：

private class GetAxiomaCredentials extends AsyncTask<ArrayList<String>, Integer, String> {

private List<NameValuePair> nvp;

public GetAxiomaCredentials(List<NameValuePair> nvp) {
this.nvp = nvp;
}

/*
use this.nvp in doInBackground(), onPostExecute(), etc...
*/

}

在您的主要课程中执行以下操作：

GetAxiomaCredentials axiomacredentials = new GetAxiomaCredentials(nameValuePairs);
axiomacredentials.execute();

<强>更新

UrlEncodedFormEntity没有构造函数需要List<String>个对象。它只接受List<? extends NameValuePair>。这就是为什么它不会编译。

将List数组作为params传递给Android AsyncTask

2 个答案: