Android共享数据ContentProvider的使用

本文来自：http://yaku2688.iteye.com/blog/1185364

ContentProvider数据共享

1.首先在AndroidManifest.xml文件中添加对外暴露的数据共享接口Content

Xml代码


<provider android:name=".UserProvider" android:authorities="com.yaku.ContentProvider.userprovider"/>

ContentProvider采用了authorities（主机名/域名）对它进行唯一标识，authorities 就是他的域名



2.Url解析

content://com.yaku.ContentProvider.userprovider/user/2

【content://】 Android定义的内容提供都的Schema

【com.yaku.ContentProvider.userprovider】 主机名或者authorities

【user】 路径

【2】 ID



示例代码：

数据结构User.java：

Java代码


package com.yaku.pojo;



public class User {

private int id;

private String name;

private int age;



public User(int id, String name, int age) {

super();

this.id = id;

this.name = name;

this.age = age;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

@Override

public String toString() {

return "User [age=" + age + ", id=" + id + ", name=" + name + "]";

}

}



数据库操作DBOpenHelper.java：

Java代码


package com.yaku.db;



import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;



public class DBOpenHelper extends SQLiteOpenHelper {

private static final String DBNAME = "yaku.db"; //数据库名称

private static final int DBVER = 1;//数据库版本



public DBOpenHelper(Context context) {

super(context, DBNAME, null, DBVER);

}



@Override

public void onCreate(SQLiteDatabase db) {

String sql = "CREATE TABLE user (userid integer primary key autoincrement, name varchar(20), age integer)";

db.execSQL(sql);//执行有更改的sql语句

}



@Override

public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {

db.execSQL("DROP TABLE IF EXISTS user");

onCreate(db);

}



}



对外共享处理类ContentProviderUser.java：

Java代码


package com.yaku.ContentProvider;



import com.yaku.db.DBOpenHelper;



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 ContentProviderUser extends ContentProvider {

private DBOpenHelper dbOpenHelper;

//常量UriMatcher.NO_MATCH表示不匹配任何路径的返回码

private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);

private static final int USERS = 1;

private static final int USER = 2;

static{

//如果match()方法匹配content://com.yaku.ContentProvider.userprovider/user路径，返回匹配码为1

MATCHER.addURI("com.yaku.ContentProvider.userprovider", "user", USERS);

//如果match()方法匹配content://com.yaku.ContentProvider.userprovider/user/123路径，返回匹配码为2

MATCHER.addURI("com.yaku.ContentProvider.userprovider", "user/#", USER);//#号为通配符

}

@Override

public int delete(Uri uri, String selection, String[] selectionArgs) {

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();

int count = 0;

switch (MATCHER.match(uri)) {

case USERS:

count = db.delete("user", selection, selectionArgs);

return count;

case USER:

//ContentUris类用于获取Uri路径后面的ID部分

long id = ContentUris.parseId(uri);

String where = "userid = "+ id;

if(selection!=null && !"".equals(selection)){

where = selection + " and " + where;

}

count = db.delete("user", where, selectionArgs);

return count;

default:

throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());

}

}



/**

* 该方法用于返回当前Url所代表数据的MIME类型。

* 如果操作的数据属于集合类型，那么MIME类型字符串应该以vnd.android.cursor.dir/开头

* 如果要操作的数据属于非集合类型数据，那么MIME类型字符串应该以vnd.android.cursor.item/开头

*/

@Override

public String getType(Uri uri) {

switch (MATCHER.match(uri)) {

case USERS:

return "vnd.android.cursor.dir/user";



case USER:

return "vnd.android.cursor.item/user";



default:

throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());

}

}



@Override

public Uri insert(Uri uri, ContentValues values) {

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();

switch (MATCHER.match(uri)) {

case USERS:

long rowid = db.insert("user", "name", values);

Uri insertUri = ContentUris.withAppendedId(uri, rowid);//得到代表新增记录的Uri

this.getContext().getContentResolver().notifyChange(uri, null);

return insertUri;



default:

throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());

}

}



@Override

public boolean onCreate() {

this.dbOpenHelper = new DBOpenHelper(this.getContext());

return false;

}



@Override

public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,

String sortOrder) {

SQLiteDatabase db = dbOpenHelper.getReadableDatabase();

switch (MATCHER.match(uri)) {

case USERS:

return db.query("user", projection, selection, selectionArgs, null, null, sortOrder);

case USER:

long id = ContentUris.parseId(uri);

String where = "userid = "+ id;

if(selection!=null && !"".equals(selection)){

where = selection + " and " + where;

}

return db.query("user", projection, where, selectionArgs, null, null, sortOrder);

default:

throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());

}

}



@Override

public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();

int count = 0;

switch (MATCHER.match(uri)) {

case USERS:

count = db.update("person", values, selection, selectionArgs);

return count;

case USER:

long id = ContentUris.parseId(uri);

String where = "userid = "+ id;

if(selection!=null && !"".equals(selection)){

where = selection + " and " + where;

}

count = db.update("user", values, where, selectionArgs);

return count;

default:

throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());

}

}

}



单元测试类（在另一个应用中）：



Java代码


package com.yaku.ContentProvider;



import android.content.ContentResolver;

import android.content.ContentValues;

import android.database.Cursor;

import android.net.Uri;

import android.test.AndroidTestCase;

import android.util.Log;



/**

* 对ContentProvider工程中的ContentProviderActivity进行单元测试

*/

public class ContentProviderActivityTest extends AndroidTestCase {

private static final String TAG = "ContentProvider";

//往内容提供者添加数据

public void testInsert() throws Throwable{

ContentResolver contentResolver = this.getContext().getContentResolver();

Uri insertUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user");

ContentValues values = new ContentValues();

values.put("name", "道长");

values.put("age", 86);

Uri uri = contentResolver.insert(insertUri, values);

Log.i(TAG, uri.toString());

}



//更新内容提供者中的数据

public void testUpdate() throws Throwable{

ContentResolver contentResolver = this.getContext().getContentResolver();

Uri updateUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user/1");

ContentValues values = new ContentValues();

values.put("name", "青眉道长");

contentResolver.update(updateUri, values, null, null);

}



//从内容提供者中删除数据

public void testDelete() throws Throwable{

ContentResolver contentResolver = this.getContext().getContentResolver();

Uri deleteUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user/1");

contentResolver.delete(deleteUri, null, null);

}



//获取内容提供者中的数据

public void testFind() throws Throwable{

ContentResolver contentResolver = this.getContext().getContentResolver();

Uri selectUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user");

Cursor cursor = contentResolver.query(selectUri, null, null, null, "userid desc");

while(cursor.moveToNext()){

int id = cursor.getInt(cursor.getColumnIndex("userid"));

String name = cursor.getString(cursor.getColumnIndex("name"));

int age = cursor.getInt(cursor.getColumnIndex("age"));

Log.i(TAG, "id="+ id + ",name="+ name+ ",age="+ age);

}

}



}



监听数据的变化：

Java代码


<span style="font-size: medium;">package com.yaku.ContentProvider;



import android.content.ContentResolver;

import android.content.ContentValues;

import android.database.Cursor;

import android.net.Uri;

import android.test.AndroidTestCase;

import android.util.Log;



/**

* 监听数据变化

*/

public class OtherContentProviderTest extends AndroidTestCase {

private static final String TAG = "OtherContentProvider";



@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);



Uri insertUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user");

ContentResolver contentResolver = this.getContentResolver();

//对指定uri进行监听，如果该uri代表的数据发生变化，就会调用PersonObserver中的onChange()

contentResolver.registerContentObserver(insertUri, true, new PersonObserver(new Handler()));

}



private final class PersonObserver extends ContentObserver{

public PersonObserver(Handler handler) {

super(handler);

}



@Override

public void onChange(boolean selfChange) {

ContentResolver contentResolver = getContentResolver();

Uri selectUri = Uri.parse("content://com.yaku.ContentProvider.userprovider/user");

Cursor cursor = contentResolver.query(selectUri, null, null, null, "userid desc");

while(cursor.moveToNext()){

int id = cursor.getInt(cursor.getColumnIndex("userid"));

String name = cursor.getString(cursor.getColumnIndex("name"));

int age = cursor.getInt(cursor.getColumnIndex("age"));

Log.i(TAG, "id="+ id + ",name="+ name+ ",age="+ age);

}

}

}

}

</span>