【移动应用开发技术】Android-ContentProvider （一）创建contentProvider

【移动应用开发技术】Android——ContentProvider（一）创建contentProvider

一、在AndroidManifest.xml文件中添加

<provider

android:name=".StudentProvider"

android:authorities="com.example.android_contentprovider2.StudentProvider"

>

</provider>二、创建数据库SqliteOpenHelperpublic

class

DbHelper

extends

SQLiteOpenHelper

{

private

static

String

name

=

"mydb.db";

private

static

int

version

=

1;//

初始的版本号是一

public

DbHelper(Context

context)

{

super(context,

name,

null,

version);

//

TODO

Auto-generated

constructor

stub

}

@Override

public

void

onCreate(SQLiteDatabase

database)

{

//

TODO

Auto-generated

method

stub

String

sql

=

"create

table

student

(id

integer

primary

key

autoincrement

,name

varchar(64)

,address

varchar(64))";

database.execSQL(sql);//

对数据库的表的创建

}

@Override

public

void

onUpgrade(SQLiteDatabase

db,

int

oldVersion,

int

newVersion)

{

//

TODO

Auto-generated

method

stub

}

}三、创建ContentProviderpublic

class

StudentProvider

extends

ContentProvider

{

private

final

String

TAG

=

"StudentProvider";

private

DbHelper

helper

=

null;

private

static

final

UriMatcher

URI_MATCHER

=

new

UriMatcher(

UriMatcher.NO_MATCH);

private

static

final

int

STUDENT

=

1;//

操作单条记录

private

static

final

int

STUDENTS

=

2;//

操作多条记录

static

{

URI_MATCHER.addURI(

"com.example.android_contentprovider2.StudentProvider",

"student",

STUDENTS);

URI_MATCHER.addURI(

"com.example.android_contentprovider2.StudentProvider",

"student/#",

STUDENT);

}

public

StudentProvider()

{

//

TODO

Auto-generated

constructor

stub

}

@Override

public

int

delete(Uri

uri,

String

selection,

String[]

selectionArgs)

{

//

TODO

Auto-generated

method

stub

int

count

=

-1;//

影响数据库的行数

try

{

int

flag

=

URI_MATCHER.match(uri);

SQLiteDatabase

database

=

helper.getWritableDatabase();

switch

(flag)

{

case

STUDENT:

//

content://com.example.android_contentprovider2.StudentProvider/student/1

//

delete

from

student

where

id

=

?

//id

通过客户端传递过来的

long

id

=

ContentUris.parseId(uri);

String

where_value

=

"

id

=

"

+

id;

if

(selection

!=

null

&&

!selection.equals(""))

{

where_value

+=

"

and

"

+

selection;

}

count

=

database.delete("student",

where_value,

selectionArgs);

break;

case

STUDENTS:

count

=

database.delete("student",

selection,

selectionArgs);

break;

}

}

catch

(Exception

e)

{

//

TODO:

handle

exception

}

return

count;

}

@Override

public

String

getType(Uri

uri)

{

//

TODO

Auto-generated

method

stub

int

flag

=

URI_MATCHER.match(uri);

switch

(flag)

{

case

STUDENT:

return

"vnd.android.cursor.item/student";

case

STUDENTS:

return

"vnd.android.cursor.dir/students";

}

return

null;

}

@Override

public

Uri

insert(Uri

uri,

ContentValues

values)

{

//

TODO

Auto-generated

method

stub

//

insert

into

student

()

(?,?);

Uri

resultUri

=

null;

int

flag

=

URI_MATCHER.match(uri);

switch

(flag)

{

case

STUDENTS:

SQLiteDatabase

database

=

helper.getWritableDatabase();

long

id

=

database.insert("student",

null,

values);//

插入当前行的行号

resultUri

=

ContentUris.withAppendedId(uri,

id);

break;

}

Log.i(TAG,

">>"

+

resultUri.toString());

return

resultUri;

}

@Override

public

boolean

onCreate()

{

//

TODO

Auto-generated

method

stub

helper

=

new

DbHelper(getContext());

return

true;

}

@Override

public

Cursor

query(Uri

uri,

String[]

projection,

String

selection,

String[]

selectionArgs,

String

sortOrder)

{

//

TODO

Auto-generated

method

stub

Cursor

cursor

=

null;

try

{

SQLiteDatabase

database

=

helper.getReadableDatabase();

int

flag

=

URI_MATCHER.match(uri);

switch

(flag)

{

case

STUDENT:

long

id

=

ContentUris.parseId(uri);

String

where_value

=

"

id

=

"

+

id;

if

(selection

!=

null

&&

!selection.equals(""))

{

where_value

+=

"

and

"

+

selection;

}

cursor

=

database.query("student",

null,

where_value,

selectionArgs,

null,

null,

null,

null);

break;

case

STUDENTS:

cursor

=

database.query("student",

null,

selection,

selectionArgs,

null,

null,

null);

break;

}

}

catch

(Exception

e)

{

//

TODO:

handle

exception

}

return

cursor;

}

@Override

public

int

update(Uri

uri,

ContentValues

values,

String

selection,

String[]

selectionArgs)

{

//

TODO

Auto-generated

method

stub

int

count

=

-1;

try

{

//

update

table

set

name

=

?

,address

=

?

where

id

=

?

SQLiteDatabase

database

=

helper.getWritableDatabase();

long

id

=

ContentUris.parseId(uri);

int

flag

=

URI_MATCHER.match(uri);

switch

(flag)

{

case

STUDENT:

String

where_value

=

"

id

=

"

+

id;

if

(selection