Question

Context context;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Context context = (Permission) this;
    // In an actual app, you'd want to request a permission when the user
    // performs an action
    // that requires that permission.
    if (Build.VERSION.SDK_INT >= 23) {
        getPermissionToReadUserContacts();
    }
}

// Identifier for the permission request
private static final int READ_CONTACTS_PERMISSIONS_REQUEST = 1;

// Called when the user is performing an action which requires the app to
// read the
// user's contacts
public void getPermissionToReadUserContacts() {
    // 1) Use the support library version
    // ContextCompat.checkSelfPermission(...) to avoid
    // checking the build version since Context.checkSelfPermission(...) is
    // only available
    // in Marshmallow
    // 2) Always check for permission (even if permission has already been
    // granted)
    // since the user can revoke permissions at any time through Settings
    if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {

        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.READ_CONTACTS)) {

            // Show an expanation to the user *asynchronously* -- don't
            // block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.

        } else {

            // No explanation needed, we can request the permission.

            ActivityCompat.requestPermissions(this,
                    new String[] { Manifest.permission.READ_CONTACTS },
                    READ_CONTACTS_PERMISSIONS_REQUEST);

            // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
            // app-defined int constant. The callback method gets the
            // result of the request.
        }
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
        String permissions[], int[] grantResults) {
    switch (requestCode) {
    case READ_CONTACTS_PERMISSIONS_REQUEST: {
        // If request is cancelled, the result arrays are empty.
        if (grantResults.length > 0
                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(this, "Read Contacts permission granted",
                    Toast.LENGTH_SHORT).show();
            // permission was granted, yay! Do the
            // contacts-related task you need to do.

        } else {
            Toast.makeText(this, "Read Contacts permission denied",
                    Toast.LENGTH_SHORT).show();
            // permission denied, boo! Disable the
            // functionality that depends on this permission.
        }
        return;
    }

    // other 'case' lines to check for other
    // permissions this app might request
    }
}
// Callback with the request from calling requestPermissions(...)
/*
 * @Override public void onRequestPermissionsResult(int requestCode, String
 * permissions[], int[] grantResults) { // Make sure it's our original
 * READ_CONTACTS request if (requestCode ==
 * READ_CONTACTS_PERMISSIONS_REQUEST) { if (grantResults.length == 1 &&
 * grantResults[0] == PackageManager.PERMISSION_GRANTED) {
 * Toast.makeText(this, "Read Contacts permission granted",
 * Toast.LENGTH_SHORT).show(); } else { Toast.makeText(this,
 * "Read Contacts permission denied", Toast.LENGTH_SHORT).show(); } } else {
 * super.onRequestPermissionsResult(requestCode, permissions, grantResults);
 * } }
 */

当我在演示应用程序中尝试此操作时，它工作正常。但是当我在项目中包含它时会抛出错误作为标题。任何帮助都将受到赞赏。这是因为我认为是上下文。 .................................................. .................................................. .................................................. .................................................. .................................................. .................................................. ..............................................

Answer 1

ContextCompat.checkSelfPermission()需要23或更高版本的支持库。

在较低级dependencies中添加build.gradle块：

compile 'com.android.support:appcompat-v7:23.1.1'

如果你有这里的旧版本（你可能有），你应该用我提供的替换泳道。

Answer 2

出现此问题是因为支持库已过期。

如果您正在使用Eclipse，我发现最简单的解决方案是右键单击该项目并转到：

Android Tools > Add support library...

如果这不能解决问题，您可能需要先更新SDK：

Window > Android SDK Manager > Install Updates

将添加/更新支持库，并且不再显示此错误。

Answer 3

您可以将项目的目标android设置为android 6.0或更高版本。然后添加android-support-v4.jar

对于ContextCompat类型，方法checkSelfPermission（Context，String）是未定义的

3 个答案: