更新时间:2023-02-23 22:16:44
您可以使用AsyncTask
,您必须进行自定义以满足您的需求,但是类似以下内容
You could use AsyncTask
, you'll have to customize to fit your needs, but something like the following
异步任务具有三种主要方法:
Async task has three primary methods:
onPreExecute()
-最常用来设置和启动进度对话框
onPreExecute()
- most commonly used for setting up and starting a progress dialog
doInBackground()
-建立连接并从服务器接收响应(请勿尝试将响应值分配给GUI元素,这是一个常见错误,无法在后台线程中完成).
doInBackground()
- Makes connections and receives responses from the server (Do NOT try to assign response values to GUI elements, this is a common mistake, that cannot be done in a background thread).
首先,我们将启动类,初始化String
以将结果保存在方法外部但在类内部,然后运行onPreExecute()
方法以设置简单的进度对话框.
First we will start the class, initialize a String
to hold the results outside of the methods but inside the class, then run the onPreExecute()
method setting up a simple progress dialog.
class MyAsyncTask extends AsyncTask<String, String, Void> {
private ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
InputStream inputStream = null;
String result = "";
protected void onPreExecute() {
progressDialog.setMessage("Downloading your data...");
progressDialog.show();
progressDialog.setOnCancelListener(new OnCancelListener() {
public void onCancel(DialogInterface arg0) {
MyAsyncTask.this.cancel(true);
}
});
}
然后,我们需要建立连接以及我们如何处理响应:
Then we need to set up the connection and how we want to handle the response:
@Override
protected Void doInBackground(String... params) {
String url_select = "http://yoururlhere.com";
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
try {
// Set up HTTP post
// HttpClient is more then less deprecated. Need to change to URLConnection
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// Read content & Log
inputStream = httpEntity.getContent();
} catch (UnsupportedEncodingException e1) {
Log.e("UnsupportedEncodingException", e1.toString());
e1.printStackTrace();
} catch (ClientProtocolException e2) {
Log.e("ClientProtocolException", e2.toString());
e2.printStackTrace();
} catch (IllegalStateException e3) {
Log.e("IllegalStateException", e3.toString());
e3.printStackTrace();
} catch (IOException e4) {
Log.e("IOException", e4.toString());
e4.printStackTrace();
}
// Convert response to string using String Builder
try {
BufferedReader bReader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"), 8);
StringBuilder sBuilder = new StringBuilder();
String line = null;
while ((line = bReader.readLine()) != null) {
sBuilder.append(line + "\n");
}
inputStream.close();
result = sBuilder.toString();
} catch (Exception e) {
Log.e("StringBuilding & BufferedReader", "Error converting result " + e.toString());
}
} // protected Void doInBackground(String... params)
最后,这里我们将分析返回值,在此示例中,它是一个JSON数组,然后关闭该对话框:
Lastly, here we will parse the return, in this example it was a JSON Array and then dismiss the dialog:
protected void onPostExecute(Void v) {
//parse JSON data
try {
JSONArray jArray = new JSONArray(result);
for(i=0; i < jArray.length(); i++) {
JSONObject jObject = jArray.getJSONObject(i);
String name = jObject.getString("name");
String tab1_text = jObject.getString("tab1_text");
int active = jObject.getInt("active");
} // End Loop
this.progressDialog.dismiss();
} catch (JSONException e) {
Log.e("JSONException", "Error: " + e.toString());
} // catch (JSONException e)
} // protected void onPostExecute(Void v)
} //class MyAsyncTask extends AsyncTask<String, String, Void>