我有一个Activity类，运行了很多Web服务，并希望使我的程序更“面向对象”，因此它可以维护且易于阅读。例如，请查看以下示例。
public class Welcome extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getSupportActionBar().hide();
setContentView(R.layout.activity_sample);
buildFitnessClient();
showUser(username,password);
}
private void buildFitnessClient() {
// Create the Google API Client
mClient = new GoogleApiClient.Builder(this)
.addApi(Fitness.SENSORS_API)
.addApi(Fitness.HISTORY_API)
.addScope(new Scope(Scopes.FITNESS_ACTIVITY_READ_WRITE))
.addConnectionCallbacks(
new GoogleApiClient.ConnectionCallbacks() {
@Override
public void onConnected(Bundle bundle) {
Log.i(TAG, "Connected!!!");
// Now you can make calls to the Fitness APIs. What to do?
// Look at some data!!
//showUser(username,password);
new InsertAndVerifyDataTask().execute();
}
@Override
public void onConnectionSuspended(int i) {
// If your connection to the sensor gets lost at some point,
// you'll be able to determine the reason and react to it here.
if (i == GoogleApiClient.ConnectionCallbacks.CAUSE_NETWORK_LOST) {
Log.i(TAG, "Connection lost. Cause: Network Lost.");
} else if (i == GoogleApiClient.ConnectionCallbacks.CAUSE_SERVICE_DISCONNECTED) {
Log.i(TAG, "Connection lost. Reason: Service Disconnected");
}
}
}
)
.addOnConnectionFailedListener(
new GoogleApiClient.OnConnectionFailedListener() {
// Called whenever the API client fails to connect.
@Override
public void onConnectionFailed(ConnectionResult result) {
Log.i(TAG, "Connection failed. Cause: " + result.toString());
if (!result.hasResolution()) {
// Show the localized error dialog
GooglePlayServicesUtil.getErrorDialog(result.getErrorCode(),
Welcome.this, 0).show();
return;
}
// The failure has a resolution. Resolve it.
// Called typically when the app is not yet authorized, and an
// authorization dialog is displayed to the user.
if (!authInProgress) {
try {
Log.i(TAG, "Attempting to resolve failed connection");
authInProgress = true;
result.startResolutionForResult(Welcome.this,
REQUEST_OAUTH);
} catch (IntentSender.SendIntentException e) {
Log.e(TAG,
"Exception while starting resolution activity", e);
}
}
}
}
)
.build();
}
@Override
protected void onStart() {
super.onStart();
// Connect to the Fitness API
Log.i(TAG, "Connecting...");
mClient.connect();
}
@Override
protected void onStop() {
super.onStop();
if (mClient.isConnected()) {
mClient.disconnect();
//showUser(username,password);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
//showUser(username,password);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_OAUTH) {
authInProgress = false;
if (resultCode == RESULT_OK) {
// Make sure the app is not already connected or attempting to connect
if (!mClient.isConnecting() && !mClient.isConnected()) {
mClient.connect();
}
}
}
}
private void showUser(final String username, final String password) {
HttpsTrustManager.allowAllSSL();
String tag_json_obj = "json_obj_req";
location = getResources().getConfiguration().locale.getCountry();
final HashMap<String, String> postParams = new HashMap<String, String>();
postParams.put("username", username);
postParams.put("password", password);
Response.Listener<JSONObject> listener;
Response.ErrorListener errorListener;
final JSONObject jsonObject = new JSONObject(postParams);
//{"password":"larissa","username":"samsungtest"}
//{"password":"larissa","username":"theo81developer@gmail.com"}
JsonObjectRequest jsonObjReq = new JsonObjectRequest(AppConfig.URL_USER_CHECK, jsonObject,
new com.android.volley.Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
// {"message":"User Information found.","user":{"username":"samsungtest","league_points":null,"team_id":"189","location":"GB","latest_steps":"0","user_type":"LEADER","nickname":"samsungtest"},"status":"success"}
//{"message":"User Information found.","user":{"username":"theo81developer@gmail.com","league_points":null,"team_id":"228","location":"GB","latest_steps":"5033","user_type":"LEADER","nickname":"Samsung User"},"status":"success"}
Log.d("TAG", response.toString());
try {
if (response.getString("status").equals("success")){
userTable(response);
localRanking(username,password,location);
globalRanking(username,password);
}
} catch (JSONException e) {
Log.e("TAG", e.toString());
}
}
}, new com.android.volley.Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
//VolleyLog.d("TAG", "Error: " + error.getMessage());
}
}) {
@Override
public String getBodyContentType() {
return "application/json; charset=utf-8";
}
};
// Adding request to request queue
AppController.getInstance().addToRequestQueue(jsonObjReq, tag_json_obj);
}
如果我从另一个类调用buildFitnessClient（）和showUser（...），我怎样才能使它工作？我尝试了一些不同的方法，比如在内部使用buildFitnessClient（）方法实现一个名为Fitness的类，但是我在View对象上获得了空指针异常。
答案 0 :(得分：0)
您可以将方法实现为静态，以便可以从另一个类或活动中调用它们，并简单地传递它可能需要的所需参数（例如上下文，视图等）。只需将它们用作 Fitness.buildFitnessClient（＆lt; variables＆gt;）
之类的东西OR
实施 singleton ，您可以在其中设置方法使用的变量，并执行您想要执行的操作。然而，这要复杂得多（至少对我而言）
** 请注意内存泄漏 **