自定义ContentProvider
一、定义
1.编写一个类，必须继承自ContentProvider类
2.实现ContentProvider类中所有的抽象方法
3.定义ContentProvider的URI
4.使用UriMatcher对象映射Uri返回代码
5.根据实际的需要编写相应方法
6.在AndroidMainfest.xml文件中使用<provider>标签注册ContentProvider
以下是实现类：
package cn.eoe.region.content.provider;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
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;
import android.util.Log;
public class RegionContentProvider extends ContentProvider
{
private static UriMatcher uriMatcher;
private static final String AUTHORITY = "cn.eoe.regioncontentprovider";
private static final int CITIES = 1;
private static final int CITY_CODE = 2;
private static final int CITY_NAME = 3;
private static final int CITIES_IN_PROVINCE = 4;
private SQLiteDatabase database;
static
{
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// content://cn.eoe.regioncontentprovider/cities
uriMatcher.addURI(AUTHORITY, "cities", CITIES);
// content://cn.eoe.regioncontentprovider/code/024
uriMatcher.addURI(AUTHORITY, "code/#", CITY_CODE);
// content://cn.eoe.regioncontentprovider/name/北京
uriMatcher.addURI(AUTHORITY, "name/*", CITY_NAME);
// content://cn.eoe.regioncontentprovider/cities_in_province/辽宁
uriMatcher
.addURI(AUTHORITY, "cities_in_province/*", CITIES_IN_PROVINCE);
}
private SQLiteDatabase openDatabase()<SPAN style="FONT-SIZE: 14px"><STRONG>//<SPAN style="BACKGROUND-COLOR: rgb(255,204,51)">写入数据库到内存卡根目录</SPAN></STRONG></SPAN>
{
try
{
String databaseFilename = "/sdcard/region.db";
if (!(new File(databaseFilename)).exists())
{
InputStream is = getContext().getResources().getAssets()
.open("region.db");
FileOutputStream fos = new FileOutputStream(databaseFilename);
byte[] buffer = new byte[8192];
int count = 0;
while ((count = is.read(buffer)) > 0)
{
fos.write(buffer, 0, count);
}
fos.close();
is.close();
}
SQLiteDatabase database = SQLiteDatabase.openOrCreateDatabase(
databaseFilename, null);
return database;
}
catch (Exception e)
{
Log.d("error", e.getMessage());
}
return null;
}
@Override
public boolean onCreate()
{
database = openDatabase();
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,<STRONG><SPAN style="BACKGROUND-COLOR: rgb(51,51,51); COLOR: #ffcc66; FONT-SIZE: 14px">//实现查找功能的关键部分</SPAN></STRONG>
String[] selectionArgs, String sortOrder)
{
Cursor cursor = null;
switch (uriMatcher.match(uri))
{
case CITIES:
cursor = database.query("v_cities_province", projection,
selection, selectionArgs, null, null, sortOrder);
break;
case CITY_CODE:
String cityCode = uri.getPathSegments().get(1);
if (selection == null)
selection = "city_code='" + cityCode + "'";
else
selection += " and (city_code='" + cityCode + "')";
cursor = database.query("t_cities", projection, selection,
selectionArgs, null, null, sortOrder);
break;
case CITY_NAME:
String cityName = uri.getPathSegments().get(1);
if (selection == null)
selection = "city_name='" + cityName + "'";
else
selection += " and (city_name='" + cityName + "')";
cursor = database.query("t_cities", projection, selection,
selectionArgs, null, null, sortOrder);
break;
case CITIES_IN_PROVINCE:
String provinceName = uri.getPathSegments().get(1);
if (selection == null)
selection = "province_name='" + provinceName + "'";
else
selection += " and (province_name='" + provinceName + "')";
cursor = database.query("v_cities_province", projection, selection,
selectionArgs, null, null, sortOrder);
break;
default:
throw new IllegalArgumentException("<" + uri + ">格式不正确.");
}
return cursor;
}
@Override
public String getType(Uri uri)
{
// TODO Auto-generated method stub
return null;
}
@Override
public Uri insert(Uri uri, ContentValues values)
{
// TODO Auto-generated method stub
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs)
{
// TODO Auto-generated method stub
return 0;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs)
{
// TODO Auto-generated method stub
return 0;
}
}
package cn.eoe.region.content.provider;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
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;
import android.util.Log;
public class RegionContentProvider extends ContentProvider
{
private static UriMatcher uriMatcher;
private static final String AUTHORITY = "cn.eoe.regioncontentprovider";
private static final int CITIES = 1;
private static final int CITY_CODE = 2;
private static final int CITY_NAME = 3;
private static final int CITIES_IN_PROVINCE = 4;
private SQLiteDatabase database;
static
{
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
// content://cn.eoe.regioncontentprovider/cities
uriMatcher.addURI(AUTHORITY, "cities", CITIES);
// content://cn.eoe.regioncontentprovider/code/024
uriMatcher.addURI(AUTHORITY, "code/#", CITY_CODE);
// content://cn.eoe.regioncontentprovider/name/北京
uriMatcher.addURI(AUTHORITY, "name/*", CITY_NAME);
// content://cn.eoe.regioncontentprovider/cities_in_province/辽宁
uriMatcher
.addURI(AUTHORITY, "cities_in_province/*", CITIES_IN_PROVINCE);
}
private SQLiteDatabase openDatabase()//写入数据库到内存卡根目录
{
try
{
String databaseFilename = "/sdcard/region.db";
if (!(new File(databaseFilename)).exists())
{
InputStream is = getContext().getResources().getAssets()
.open("region.db");
FileOutputStream fos = new FileOutputStream(databaseFilename);
byte[] buffer = new byte[8192];
int c补充：移动开发 , Android ,
