创建自己的内容提供器
创建自己的内容提供器
DatabaseTest
新建内容提供器
它会自动在AndroidMainfest.xml中生成定义
接下来实现继承的方法
package demo.jq.com.databasetest;
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;
/**
* @author jim
*/
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 = "demo.jq.com.databasetest.provider";
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 int delete(Uri uri, String selection, String[] selectionArgs) {
// 删除数据
SQLiteDatabase db = dbHelper.getReadableDatabase();
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 String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
return "book.dir";
case BOOK_ITEM:
return "book.item";
case CATEGORY_DIR:
return "category.dir";
case CATEGORY_ITEM:
return "category.item";
}
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
// 添加数据
SQLiteDatabase db = dbHelper.getWritableDatabase();
Uri uriReturn = null;
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
case BOOK_ITEM:
long newBookId = db.insert("Book",null,values);
uriReturn = Uri.parse("content://"+AUTHORITY+"/book/"+newBookId);
break;
case CATEGORY_DIR:
case CATEGORY_ITEM:
long newCategoryId = db.insert("Category",null,values);
uriReturn = Uri.parse("content://"+AUTHORITY+"/category/"+newCategoryId);
break;
default:
break;
}
return uriReturn;
}
@Override
public boolean onCreate() {
dbHelper = new MyDatabaseHelper(getContext(),"BookStore.db",null,2);
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// 查询数据
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = null;
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
cursor = db.query("Book",projection,selection,selectionArgs,null,null,sortOrder);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);
cursor = db.query("Book",projection,"id = ?",new String[]{bookId},null,null,sortOrder);
break;
case CATEGORY_DIR:
cursor = db.query("Category",projection,selection,selectionArgs,null,null,sortOrder);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
cursor = db.query("Category",projection,"id = ?",new String[]{categoryId},null,null,sortOrder);
break;
default:
break;
}
return cursor;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// 修改数据
SQLiteDatabase db = dbHelper.getReadableDatabase();
int updatedRows = 0;
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
updatedRows = db.update("Book",values,selection,selectionArgs);
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,selection,selectionArgs);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
updatedRows = db.update("Category",values,"id = ?",new String[] {categoryId});
break;
default:
break;
}
return updatedRows;
}
}
提供好对外的内容之后。
下面创建一个ProviderTest进行测试。
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="@+id/add_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add to Book"
/>
<Button
android:id="@+id/update_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Update Book"
/>
<Button
android:id="@+id/delete_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Delete From Book"
/>
<Button
android:id="@+id/query_data"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Query From Book"
/>
</LinearLayout>
package demo.jq.com.providertest;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
/**
* @author jim
*/
public class MainActivity extends AppCompatActivity {
private String newId;
private static final String TAG = "MainActivity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 初始化添加数据按钮
Button addData = (Button) findViewById(R.id.add_data);
addData.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// 添加数据
Uri uri = Uri.parse("content://demo.jq.com.databasetest.provider/book");
ContentValues values = new ContentValues();
values.put("name","A Clash of Kings");
values.put("author","George Martin");
values.put("pages",1040);
values.put("price",22.85);
Uri newUri = getContentResolver().insert(uri,values);
newId = newUri.getPathSegments().get(1);
}
});
// 更改数据
Button updateData = (Button) findViewById(R.id.update_data);
updateData.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://demo.jq.com.databasetest.provider/book/"+newId);
ContentValues values = new ContentValues();
values.put("name","A Storm of Swords");
values.put("pages",1246);
values.put("price",24.05);
getContentResolver().update(uri,values,null,null);
}
});
// 删除数据
Button deleteData = (Button) findViewById(R.id.delete_data);
deleteData.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://demo.jq.com.databasetest.provider/book/"+newId);
getContentResolver().delete(uri,null,null);
}
});
// 查询数据
Button queryData = (Button) findViewById(R.id.query_data);
queryData.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// 查询数据
Uri uri = Uri.parse("content://demo.jq.com.databasetest.provider/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(TAG,"book name is "+name);
Log.d(TAG,"book author is "+author);
Log.d(TAG,"book pages is "+pages);
Log.d(TAG,"book price is "+price);
}
}
cursor.close();
}
});
}
}
测试有效哦，可以通过uri，在另一个程序中操作数据和获取数据。
