这是我用于请求权限以使其在 API 23 上工作的内容，但这产生了一个问题，即代码不想通过 API 21 发送信息。
private boolean checkAndRequestPermissions() {
int permissionSendMessage = ContextCompat.checkSelfPermission(this,
Manifest.permission.READ_CONTACTS);
int locationPermission = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION);
List<String> listPermissionsNeeded = new ArrayList<>();
if (locationPermission != PackageManager.PERMISSION_GRANTED) {
listPermissionsNeeded.add(Manifest.permission.ACCESS_FINE_LOCATION);
}
if (permissionSendMessage != PackageManager.PERMISSION_GRANTED) {
listPermissionsNeeded.add(Manifest.permission.READ_CONTACTS);
}
if (!listPermissionsNeeded.isEmpty()) {
ActivityCompat.requestPermissions(this, listPermissionsNeeded.toArray(new String[listPermissionsNeeded.size()]),REQUEST_ID_MULTIPLE_PERMISSIONS);
return false;
}
return true;
}
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
Log.d(TAG, "Permission callback called-------");
switch (requestCode) {
case REQUEST_ID_MULTIPLE_PERMISSIONS: {
Map<String, Integer> perms = new HashMap<>();
// Initialize the map with both permissions
perms.put(Manifest.permission.READ_CONTACTS, PackageManager.PERMISSION_GRANTED);
perms.put(Manifest.permission.ACCESS_FINE_LOCATION, PackageManager.PERMISSION_GRANTED);
// Fill with actual results from user
if (grantResults.length > 0) {
for (int i = 0; i < permissions.length; i++)
perms.put(permissions[i], grantResults[i]);
// Check for both permissions
if (perms.get(Manifest.permission.READ_CONTACTS) == PackageManager.PERMISSION_GRANTED
&& perms.get(Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "contacts & location services permission granted");
// process the normal flow
//else any one or both the permissions are not granted
} else {
Log.d(TAG, "Some permissions are not granted ask again ");
//permission is denied (this is the first time, when "never ask again" is not checked) so ask again explaining the usage of permission
// // shouldShowRequestPermissionRationale will return true
//show the dialog or snackbar saying its necessary and try again otherwise proceed with setup.
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.SEND_SMS) || ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.ACCESS_FINE_LOCATION)) {
showDialogOK("Contacts and Location Services Permission required for this app",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
switch (which) {
case DialogInterface.BUTTON_POSITIVE:
checkAndRequestPermissions();
break;
case DialogInterface.BUTTON_NEGATIVE:
// proceed with logic by disabling the related features or quit the app.
break;
}
}
});
}
//permission is denied (and never ask again is checked)
//shouldShowRequestPermissionRationale will return false
else {
Toast.makeText(this, "Go to settings and enable permissions", Toast.LENGTH_LONG)
.show();
// //proceed with logic by disabling the related features or quit the app.
}
}
}
}
}
}
如果我删除此权限，API 21 将再次完美运行。
public void sendGetRequest(View v)
{
int version = Build.VERSION.SDK_INT;
if (version >= 23)
{
if(checkAndRequestPermissions())
{ //EXECUTE JSON
new GetClass(this).execute();
}
}
else
{
new GetClass(this).execute();
}
}
使用 API 21 打开时的堆栈跟踪：
05-02 15:02:41.830 12952-13251/com.sandro.openalprsample E/Volley: [9140] NetworkDispatcher.run: Unhandled exception java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at libcore.net.UriCodec.encode(UriCodec.java:132)
at java.net.URLEncoder.encode(URLEncoder.java:57)
at com.android.volley.Request.encodeParameters(Request.java:480)
at com.android.volley.Request.getBody(Request.java:466)
at com.android.volley.toolbox.HurlStack.addBodyIfExists(HurlStack.java:236)
at com.android.volley.toolbox.HurlStack.setConnectionParametersForRequest(HurlStack.java:210)
at com.android.volley.toolbox.HurlStack.performRequest(HurlStack.java:106)
at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:96)
at com.android.volley.NetworkDispatcher.run(NetworkDispatcher.java:112)
05-02 15:02:41.860 12952-12952/com.sandro.openalprsample E/ViewRootImpl: sendUserActionEvent() mView == null
权限：
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.USE_CREDENTIALS" />
<uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS"/>
<uses-permission android:name="android.permission.READ_PROFILE" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
如果需要更多信息，我可以更新。