android 内容提供者(ContentProvider)共享SQLite

android 内容提供者(ContentProvider)共享SQLite

ContentProvider为android提供了一种不同应用之间共享数据的可能，次列提供ContentProvider将SQLite的数据库表 class 共享出来。

1、创建类DBProvider继承ContentProvider，并且重写以下方法：

a、onCreate() //创建
b、query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder)//查找
c、getType(Uri uri)//返回请求的数据类型
d、insert(Uri uri, ContentValues values)//插入数据
e、delete(Uri uri, String selection, String[] selectionArgs)//删除数据
f、update(Uri uri, ContentValues values, String selection,
String[] selectionArgs)//更新数据

2、在清单文件中标签下注册内容提供者：

<provider
android:name=".DBProvider"  //name为类DBProvider的名字，前面加 “.”
android:authorities="com.example.class_contentporvider_test.DBProvider" >
</provider>//自定义的内容提供者访问uri

3、创建DBHelper类继承SQLiteOpenHelper，并重写如下方法，创建SQLite文件：

public DBHelper(Context context) {
super(context, "test.db", null, 1);
// TODO Auto-generated constructor stub

}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
String sql = "create table class(id integer primary key autoincrement,name varchar(64),number varchar(64))";
db.execSQL(sql);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}

关于SQLite的使用详情，请参照我的上一篇博文：http://blog.csdn.net/q296264785/article/details/53155739

ContentProvider的继承类DBProvider：

UriMatcher 工具类为Uri解析提供匹配规则，UriMatcher 的实现类提供addURI方法可以往UriMatcher 添加匹配规则。addURI的第一个参数为清单文件中我们自定义的android:authorities=”com.example.class_contentporvider_test.DBProvider”；

第二个参数为访问数据库文件的目录，“*”“#”为通配符，分别代表“字符”“数字”；第三个为自定义常量。

private DBHelper helper;
private final static UriMatcher URI_MATCHER = new UriMatcher(
UriMatcher.NO_MATCH);
private final static int one = 1;
private final static int two = 2;
static {
// 添加匹配规则
URI_MATCHER.addURI("com.example.class_contentporvider_test.DBProvider",
"class", two);// 字符
URI_MATCHER.addURI("com.example.class_contentporvider_test.DBProvider",
"class/#", one);// 数字
}

文件目录表



MainActivity ：

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

DBHelper 类：

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {
private static final String SLQ_NAME = "mydb.db";
private static final int VERSION = 1; // ctrl + shift + x 小写变大写

public DBHelper(Context context) {
super(context, SLQ_NAME, null, VERSION);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
String sql = "create table person(_pid integer primary key autoincrement,name varchar(64),address varchar(64))";
db.execSQL(sql);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}

}

PersonContentProvider 类

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 DBHelper helper;
private final static UriMatcher URI_MATCHER = new UriMatcher(
UriMatcher
d1fa
.NO_MATCH);
private final static int PERSONS = 1;// 操作多条记录
private final static int PERSON = 2;// 操作单行记录
static {
// url ，路径 ，
URI_MATCHER.addURI(
//    "content://com.example.class_contentprovider.PersonContentProvider/person"  添加
"com.example.class_contentprovider.PersonContentProvider",
"person", PERSONS);
URI_MATCHER.addURI(
"com.example.class_contentprovider.PersonContentProvider",
"person/#", PERSON);
//相当于 "com.example.class_contentprovider.PersonContentProvider" + "person/#" + PERSON 的uil
}

@Override
public boolean onCreate() {
// TODO Auto-generated method stub
helper = new DBHelper(getContext());
return false;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
Cursor cursor = null;
int flag = URI_MATCHER.match(uri);
SQLiteDatabase database = helper.getReadableDatabase();
switch (flag) {
case PERSON:
long _id = ContentUris.parseId(uri);
String where_value = "_pid = " + _id;
if (selection != null && !selection.equals("")) {
where_value += selection;
}
cursor = database.query("person", projection, where_value,
selectionArgs, null, null, sortOrder);
break;
case PERSONS:
cursor = database.query("person", projection, selection,
selectionArgs, null, null, sortOrder);
break;

}
return cursor;
}

@Override
public String getType(Uri uri) {// 返回处理请求的数据类型
// TODO Auto-generated method stub
// 先解析uri,判断mime的类型
int flag = URI_MATCHER.match(uri);
switch (flag) {
case PERSON:

return "vnd.android.cursor.item/person";
case PERSONS:

return "vnd.android.cursor.dir/person";
}
return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
// TODO Auto-generated method stub
Uri result = null;
int flag = URI_MATCHER.match(uri);
switch (flag) {
case PERSONS:
SQLiteDatabase database = helper.getReadableDatabase();
long id = database.insert("person", null, values);
result = ContentUris.withAppendedId(uri, id);
break;
}
return result;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// TODO Auto-generated method stub
int flag = URI_MATCHER.match(uri);
SQLiteDatabase database = helper.getWritableDatabase();
int count = 0;
switch (flag) {
case PERSON:
long _id = ContentUris.parseId(uri);
String where_value = "_pid = " + _id;
if (selection != null && !selection.equals("")) {
where_value += selection;
}
count = database.delete("person", where_value, selectionArgs);
break;
case PERSONS:
count = database.delete("person", selection, selectionArgs);
break;
}
return count;
}

@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
int flag = URI_MATCHER.match(uri);
int count = 0;
SQLiteDatabase database = helper.getWritableDatabase();
switch (flag) {
case PERSON:
long _id = ContentUris.parseId(uri);
String where_value = "_pid = " + _id;
if (selection != null && !selection.equals("")) {
where_value += selection;
}
count = database.update("person", values, where_value,
selectionArgs);
break;
}
return count;
}

}

单元测试类：

import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;

public class MyTest extends AndroidTestCase {
public void add() {// 添加
ContentResolver contentResolver = getContext().getContentResolver();
ContentValues values = new ContentValues();
values.put("name", "源信");
values.put("address", "高新区");
Uri uri = Uri
.parse("content://com.example.class_contentprovider.PersonContentProvider/person");
contentResolver.insert(uri, values);
}

public void del() {// 删除
ContentResolver contentResolver = getContext().getContentResolver();
Uri uri = Uri
.parse("content://com.example.class_contentprovider.PersonContentProvider/person");
Uri new_uri = ContentUris.withAppendedId(uri, 1);
contentResolver.delete(new_uri, null, null);
}

public void query() {// 查找
ContentResolver contentResolver = getContext().getContentResolver();
Uri uri = Uri
.parse("content://com.example.class_contentprovider.PersonContentProvider/person");
Uri new_uri = ContentUris.withAppendedId(uri, 2);
Cursor cursor = contentResolver.query(new_uri, null, null, null, null);
while (cursor.moveToNext()) {
String str = cursor.getString(cursor.getColumnIndex("name"));
System.out.println("---query->>" + str);
}
}
}