我有App A有内容提供商，它工作正常。 代码是：
public class StudentsProvider extends ContentProvider {
static final String PROVIDER_NAME = "com.example.mycontentprovider";
static final String URL = "content://" + PROVIDER_NAME + "/students";
static final Uri CONTENT_URI = Uri.parse(URL);
static final String _ID = "_id";
static final String NAME = "name";
static final String GRADE = "grade";
private static HashMap<String, String> STUDENTS_PROJECTION_MAP;
static final int STUDENTS = 1;
static final int STUDENT_ID = 2;
static final UriMatcher uriMatcher;
static{
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(PROVIDER_NAME, "students", STUDENTS);
uriMatcher.addURI(PROVIDER_NAME, "students/#", STUDENT_ID);
}
/**
* Database specific constant declarations
*/
private SQLiteDatabase db;
static final String DATABASE_NAME = "College";
static final String STUDENTS_TABLE_NAME = "students";
static final int DATABASE_VERSION = 1;
static final String CREATE_DB_TABLE =
" CREATE TABLE " + STUDENTS_TABLE_NAME +
" (_id INTEGER PRIMARY KEY AUTOINCREMENT, " +
" name TEXT NOT NULL, " +
" grade TEXT NOT NULL);";
/**
* Helper class that actually creates and manages
* the provider's underlying data repository.
*/
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(CREATE_DB_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + STUDENTS_TABLE_NAME);
onCreate(db);
}
}
@Override
public boolean onCreate() {
Context context = getContext();
DatabaseHelper dbHelper = new DatabaseHelper(context);
/**
* Create a write able database which will trigger its
* creation if it doesn't already exist.
*/
db = dbHelper.getWritableDatabase();
return (db == null)? false:true;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
/**
* Add a new student record
*/
long rowID = db.insert( STUDENTS_TABLE_NAME, "", values);
/**
* If record is added successfully
*/
if (rowID > 0)
{
Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID);
getContext().getContentResolver().notifyChange(_uri, null);
return _uri;
}
throw new SQLException("Failed to add a record into " + uri);
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
qb.setTables(STUDENTS_TABLE_NAME);
switch (uriMatcher.match(uri)) {
case STUDENTS:
qb.setProjectionMap(STUDENTS_PROJECTION_MAP);
break;
case STUDENT_ID:
qb.appendWhere( _ID + "=" + uri.getPathSegments().get(1));
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
if (sortOrder == null || sortOrder == ""){
/**
* By default sort on student names
*/
sortOrder = NAME;
}
Cursor c = qb.query(db, projection, selection, selectionArgs,
null, null, sortOrder);
/**
* register to watch a content URI for changes
*/
c.setNotificationUri(getContext().getContentResolver(), uri);
return c;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)){
case STUDENTS:
count = db.delete(STUDENTS_TABLE_NAME, selection, selectionArgs);
break;
case STUDENT_ID:
String id = uri.getPathSegments().get(1);
count = db.delete( STUDENTS_TABLE_NAME, _ID + " = " + id +
(!TextUtils.isEmpty(selection) ? " AND (" +
selection + ')' : ""), selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)){
case STUDENTS:
count = db.update(STUDENTS_TABLE_NAME, values,
selection, selectionArgs);
break;
case STUDENT_ID:
count = db.update(STUDENTS_TABLE_NAME, values, _ID +
" = " + uri.getPathSegments().get(1) +
(!TextUtils.isEmpty(selection) ? " AND (" +
selection + ')' : ""), selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri );
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)){
/**
* Get all student records
*/
case STUDENTS:
return "vnd.android.cursor.dir/vnd.example.students";
/**
* Get a particular student
*/
case STUDENT_ID:
return "vnd.android.cursor.item/vnd.example.students";
default:
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
}
}
App A的清单文件是：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.mycontentprovider"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.mycontentprovider.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider android:name="StudentsProvider"
android:authorities="com.example.mycontentprovider"
android:exported="true"
android:grantUriPermissions="true"
android:readPermission="com.example.mycontentprovider.permRead"
>
</provider>
</application>
当我尝试在App B中访问此内容提供程序时，我收到以下错误：
08-20 10:55:12.232: I/System.out(2620): Error123 : java.lang.SecurityException:
Permission Denial: reading com.example.mycontentprovider.StudentsProvider uri
content://com.example.mycontentprovider/students from pid=2620, uid=10081 requires
android.permission.permRead, or grantUriPermission()
即使B的清单文件中已有权限。
App B代码是：
Uri yourURI = Uri.parse("content://com.example.mycontentprovider/students");
ContentProviderClient yourCR = getContentResolver().acquireContentProviderClient(yourURI );
Cursor c =yourCR.query(yourURI, null, null, null, null );
Toast.makeText(getApplicationContext(), c.getCount(), Toast.LENGTH_LONG).show();
App B的清单文件是：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.test33"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="com.example.mycontentprovider.permRead" />
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
这里有人可以告诉我这里有什么不对/缺失。
非常感谢。
答案 0 :(得分：5)
您需要将权限声明为应用程序A.
<permission
android:name="com.example.mycontentprovider.permRead"
android:description="@string/permission_desc"
android:label="@string/permission_label"
android:protectionLevel="signature" />
并添加
<uses-permission android:name="com.example.mycontentprovider.permRead" />
进入相同的应用程序A。
您需要阅读How to use custom permissions in Android?和permission doc。
答案 1 :(得分：1)
在App A的AndroidManifest.xml中，provider标签应该是这样的：
<provider android:name="StudentsProvider"
android:authorities="com.example.mycontentprovider"
android:exported="true">
在这种情况下，访问此类内容提供商不需要特定权限。所以在App B中，这条线变得毫无用处：
<uses-permission android:name="com.example.mycontentprovider.permRead" />