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我剛剛接觸Android並通過書籍學習它。請幫助我發現我的小練習計劃中可能出現的錯誤。我可以成功創建數據庫，但是我無法使用我的查詢函數瀏覽SQLite數據庫的結果，因爲有一個異常「無法找到com.latrobe.database的提供程序信息」。無法獲得內容提供者
Exception:06-10 01:13:55.510 25546-25546/com.latrobe.database E/ActivityThread: Failed to find provider info for com.latrobe.database
06-10 01:13:55.962 25546-25655/com.latrobe.database E/Surface: getSlotFromBufferLocked: unknown buffer: 0x7f2949cda5c0
06-10 01:14:00.401 25546-25546/com.latrobe.database E/ActivityThread: Failed to find provider info for com.latrobe.database
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.latrobe.database">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<provider
android:name=".DatabaseProvider"
android:authorities="com.latrobe.database.DatabaseProvider"
android:exported="true">
</provider>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
package com.latrobe.database;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
/**
* Created by hexinhao on 16/5/30.
*/
public class MyDatabaseHelper extends SQLiteOpenHelper {
public static final String CREATE_BOOK = "create table book ("
+ "id integer primary key autoincrement, "
+ "author text, "
+ "price real, "
+ "pages integer, "
+ "name text)";
public static final String CREATE_CATEGORY = "create table Category (" + "id integer primary key autoincrement, "
+ "category_name text, "
+ "category_code integer)";
private Context mContext;
public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
mContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_BOOK);
db.execSQL(CREATE_CATEGORY);
Toast.makeText(mContext, "Create succeeded", Toast.LENGTH_SHORT).show();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists Book");
db.execSQL("drop table if exists Category");
onCreate(db);
}
}
package com.latrobe.database;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.annotation.Nullable;
public class DatabaseProvider extends ContentProvider {
public static final int BOOK_DIR = 0;
public static final int BOOK_ITEM = 1;
public static final int CATEGORY_DIR = 2;
public static final int CATEGORY_ITEM = 3;
public static final String AUTHORITY = "com.latrobe.database";
private static UriMatcher uriMatcher;
private MyDatabaseHelper dbHelper;
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(AUTHORITY, "book", BOOK_DIR);
uriMatcher.addURI(AUTHORITY, "book/#", BOOK_ITEM);
uriMatcher.addURI(AUTHORITY, "category", CATEGORY_DIR);
uriMatcher.addURI(AUTHORITY, "category/#", CATEGORY_ITEM);
}
@Override
public boolean onCreate() {
MyDatabaseHelper dbHelper = new MyDatabaseHelper(getContext(),"BookStore.db",null,2);
return true;
}
@Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = null;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
cursor = db.query("Book",null, null, null, null, null, null);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);
cursor = db.query("Book",null,"id=?",new String[]{bookId},null,null,null);
break;
case CATEGORY_DIR:
cursor = db.query("Category",null,null,null,null,null,null,null);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
cursor = db.query("Category",null,"id=?",new String[]{categoryId},null,null,null);
break;
default:
break;
}
return cursor;
}
@Nullable
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
return "vnd.android.cursor.dir/vnd.com.latrobe.database.book";
case BOOK_ITEM:
return "vnd.android.cursor.dir/vnd.com.latrobe.database.book";
case CATEGORY_DIR:
return "vnd.android.cursor.dir/vnd.com.latrobe.database.Category";
case CATEGORY_ITEM:
return "vnd.android.cursor.dir/vnd.com.latrobe.database.Category";
}
return null;
}
@Nullable
@Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
Uri uriReturn = null;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
break;
case BOOK_ITEM:
long newBookId = db.insert("Book",null,values);
uriReturn = Uri.parse("Content://"+AUTHORITY+"/book/"+newBookId);
break;
case CATEGORY_DIR:
break;
case CATEGORY_ITEM:
long newCategoryId = db.insert("Category",null,values);
uriReturn = Uri.parse("Content://"+AUTHORITY+"/category/"+newCategoryId);
break;
default:
break;
}
return uriReturn;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// 刪除數據
SQLiteDatabase db = dbHelper.getWritableDatabase();
int deletedRows = 0;
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
deletedRows = db.delete("Book", selection, selectionArgs);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);
deletedRows = db.delete("Book", "id = ?", new String[] { bookId }); break;
case CATEGORY_DIR:
deletedRows = db.delete("Category", selection, selectionArgs); break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
deletedRows = db.delete("Category", "id = ?", new String[]
{ categoryId });
break;
default:
break;
}
return deletedRows;
}
@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
int updatedRows = 0;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
updatedRows = db.update("Book",values,null,null);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);
updatedRows=db.update("Book",values,"id=?",new String[]{bookId});
break;
case CATEGORY_DIR:
updatedRows = db.update("Category",values,null,null);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
updatedRows=db.update("Category",values,"id=?",new String[]{categoryId});
break;
default:
break;
}
return updatedRows;
}
}
package com.latrobe.database;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
private MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);
Button createDatabase = (Button) findViewById(R.id.create_database);
createDatabase.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dbHelper.getWritableDatabase();
}
});
Button addData = (Button) findViewById(R.id.add_data);
addData.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name", "The Da Vinci Code");
values.put("author", "Dan Brown");
values.put("pages", 454);
values.put("price", 16.96);
db.insert("Book", null, values);
values.clear();
values.put("name", "The Lost Symbol");
values.put("author", "Dan Brown");
values.put("pages", 510);
values.put("price", 19.95);
db.insert("Book", null, values);
}
});
Button updateData = (Button) findViewById(R.id.update_data);
updateData.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("price", 10.99);
db.update("Book", values, "name = ?",
new String[] { "The Da Vinci Code" });
}
});
Button deleteButton = (Button) findViewById(R.id.delete_data);
deleteButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.delete("Book", "pages > ?", new String[] { "500" });
}
});
Button queryButton = (Button) findViewById(R.id.query_data);
queryButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://com.latrobe.database/book");
Cursor cursor = getContentResolver().query(uri, null, null,
null, null);
if (cursor != null) {
while (cursor.moveToNext()) {
String name = cursor.getString(cursor
.getColumnIndex("name"));
String author = cursor.getString(cursor
.getColumnIndex("author"));
int pages = cursor.getInt(cursor
.getColumnIndex("pages"));
double price = cursor.getDouble(cursor
.getColumnIndex("price"));
Log.d("MainActivity", "book name is " + name);
Log.d("MainActivity", "book author is " + author);
Log.d("MainActivity", "book pages is " + pages);
Log.d("MainActivity", "book price is " + price);
}
cursor.close();
}
}
});
Button replaceData = (Button) findViewById(R.id.replace_data);
replaceData.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.beginTransaction();
try {
db.delete("Book", null, null);
// if (true) {
// throw new NullPointerException();
// }
ContentValues values = new ContentValues();
values.put("name", "Game of Thrones");
values.put("author", "George Martin");
values.put("pages", 720);
values.put("price", 20.85);
db.insert("Book", null, values);
db.setTransactionSuccessful();
} catch (Exception e) {
e.printStackTrace();
} finally {
db.endTransaction();
}
}
});
}
}
是的，我忘了粘貼另一個程序的代碼，它要求內容提供者訪問其他應用程序的數據庫。但是現在，我解決了這個問題，我沒有清楚地理解提供程序中名稱和權限的含義，但是我只是將其修改爲正確的，所以現在可以在自己的程序中使用contentProvider，但也可以通過其他程序訪問。感謝您的回覆。 –