Android 中常用代码片段

<TextView
android:id="@+id/tvInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />

<ProgressBar
android:layout_below="@id/tvInfo"
android:id="@+id/asyncPb"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:visibility="gone" />

public class MainActivity extends Activity {
private ProgressBar asyncPb = null;
private TextView tvInfo = null;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

tvInfo = (TextView)findViewById(R.id.tvInfo);

String params = "Welcome to here";
new MyAsyncTask().execute(params);
}

private class MyAsyncTask extends AsyncTask<String, Integer, String>{
@Override
protected void onPreExecute() {
//做一些预处理
asyncPb = (ProgressBar)findViewById(R.id.asyncPb);
asyncPb.setVisibility(View.VISIBLE);
}

@Override
protected String doInBackground(String... params) {
//执行耗时操作，网络任务、文件操作、数据库操作、复杂计算操作
int myProgress = 0;
int length = params[0].length();

for(int i=1; i<=length; i++){
myProgress = i;
//模拟耗时操作
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
publishProgress((int)((myProgress/(float)length)*100));
}

//它将传递给onPostExecute
return params[0];
}

@Override
protected void onProgressUpdate(Integer... values) {
//更新进度条
asyncPb.setProgress(values[0]);
tvInfo.setText("已加载："+(values[0])+"%");
}

@Override
protected void onPostExecute(String result) {
//更新UI
tvInfo.setText("加载完成："+result);
}
}
}

public static String getRequest(String url){
String result = "";
HttpClient client = new DefaultHttpClient();

HttpGet get = new HttpGet(url);

try {
HttpParams httpParams = client.getParams();

HttpConnectionParams.setConnectionTimeout(httpParams, 3000);
HttpConnectionParams.setSoTimeout(httpParams, 5000);

HttpResponse response = client.execute(get);

if(response.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
result = EntityUtils.toString(response.getEntity()).trim();
}
} catch (Exception e) {
//连接超时
}

return result;
}

private RequestQueue rQueue = null;

rQueue = WzhVolley.getRequestQueue();

StringRequest postRequest = new StringRequest(
Request.Method.POST,
URL,
createDoSuccess(),
createDoError()){
protected Map<String,String> getParams(){
Map<String,String> params = new HashMap<String,String>();
params.put(key,value);
return params;
}
};

postRequest.setRetryPolicy(new
DefaultRetryPolicy(WR.DEFAULT_TIMEOUT_MS, WR.DEFAULT_MAX_RETRIES, WR.DEFAULT_BACKOFF_MULT));
rQueue.add(postRequest);

private Response.Listener<String> createDoSuccess(){
return new Response.Listener<String>(){
public void onResponse(String arg0){
//...
JSONObject jsonObj = new JSONObject(arg0);
//or
JSONArray jsonArr = new JSONArray(arg0);
}
};
}
private Response.ErrorListener createDoError(){
return new Response.ErrorListener(){
public void onErrorResponse(VolleyError arg0){
//...
}
};
}