Android 下ContentProvider的学习
使用contentProvider
1、要先继承contentProvider
2、要在配置文件中声明contentProvider
<permission android:name="aa.bb.cc.read" ></permission>
<permission android:name="aa.bb.cc.write" ></permission>
<provider
android:name=".providers.PersonContentProvider"
android:authorities="com.itheima28.sqlitedemo.providers.PersonContentProvider"
android:readPermission="aa.bb.cc.read"
android:writePermission="aa.bb.cc.write" >
</provider>
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
public class PersonContentProvider extends ContentProvider {
private static final String AUTHORITY = "com.itheima28.sqlitedemo.providers.PersonContentProvider";
private static final int PRESON_INSERT_CODE = 0;// 操作person表添加的操作的uri匹配码
private static final int PERSON_DELETE_CODE = 1;
private static final int PERSON_UPDATE_CODE = 2;
private static final int PERSON_QUERY_ALL_CODE = 3;
private static final int PERSON_QUERY_ITEM_CODE = 4;
private static UriMatcher uriMatcher;
private PersonSQLiteOpenHelper mOpenHelper;// person表的数据库帮助对象
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// 添加一些uri(分机号)
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/insert
uriMatcher.addURI(AUTHORITY, "person/insert", PRESON_INSERT_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/delete
uriMatcher.addURI(AUTHORITY, "person/delete", PERSON_DELETE_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/update
uriMatcher.addURI(AUTHORITY, "person/update", PERSON_UPDATE_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/queryAll
uriMatcher.addURI(AUTHORITY, "person/queryAll", PERSON_QUERY_ALL_CODE);
// content://com.itheima28.sqlitedemo.providers.PersonContentProvider/person/query/#
uriMatcher.addURI(AUTHORITY, "person/query/#", PERSON_QUERY_ITEM_CODE);
}
@Override
public boolean onCreate() {
mOpenHelper = new PersonSQLiteOpenHelper(getContext());
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
switch (uriMatcher.match(uri)) {
case PERSON_QUERY_ALL_CODE: // 查询所有人的uri
if(db.isOpen()) {
Cursor cursor = db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
return cursor;
// db.close(); 返回cursor结果集时, 不可以关闭数据库
}
break;
case PERSON_QUERY_ITEM_CODE:// 查询的是单条数据, uri末尾出有一个id
if(db.isOpen()) {
long id = ContentUris.parseId(uri);
Cursor cursor = db.query("person", projection, "_id = ?", new String[]{id + ""}, null, null, sortOrder);
return cursor;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return null;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
case PERSON_QUERY_ALL_CODE: // 返回多条的MIME-type
return "vnd.android.cursor.dir/person";
case PERSON_QUERY_ITEM_CODE: // 返回单条的MIME-TYPE
return "vnd.android.cursor.item/person";
default:
break;
}
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values) {
switch (uriMatcher.match(uri)) {
case PRESON_INSERT_CODE:// 添加人到person表中
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
long id = db.insert("person", null, values);
db.close();
return ContentUris.withAppendedId(uri, id);
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
switch (uriMatcher.match(uri)) {
case PERSON_DELETE_CODE:// 在person表中删除数据的操作
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
int count = db.delete("person", selection, selectionArgs);
db.close();
return count;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return 0;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
switch (uriMatcher.match(uri)) {
case PERSON_UPDATE_CODE: // 更新person表的操作
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()) {
int count = db.update("person", values, selection, selectionArgs);
db.close();
return count;
}
break;
default:
throw new IllegalArgumentException("uri不匹配: " + uri);
}
return 0;
}
}