//本来这样写的,但是每次运行都要把db文件导入到/data/data/com.xx.demo_weather,有没有其他方法??
db = SQLiteDatabase.openOrCreateDatabase(
"/data/data/com.xx.demo_weather/chinacity.db", null);
anroid数据库
解决方案 »
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将db文件放在res的raw路径(可以自己添加这个路径)下面,要打开它的时候这样:
private String filename = DB_PATH+"/"+DB_NAME;
public void open()throws SQLException
{
writefromraw(filename);
db = opendatabase();
}
private void writefromraw(String dbfile) {
// TODO Auto-generated method stub
try {
if (!(new File(dbfile).exists())) {
InputStream is = mContext.getResources().openRawResource(
R.raw.livetv_database);
FileOutputStream fos = new FileOutputStream(dbfile);
byte[] buffer = new byte[BUFFER_SIZE];
int count = 0;
while ((count = is.read(buffer)) > 0) {
fos.write(buffer, 0, count);
}
fos.close();
is.close();
}
} catch (FileNotFoundException e) {
Log.e("Database", "File not found");
e.printStackTrace();
} catch (IOException e) {
Log.e("Database", "IO exception");
e.printStackTrace();
} }DB_PATH我是这样定义的:
public static final String DB_PATH = "/data"+Environment.getDataDirectory().getAbsolutePath()
+"/"+PACKAGE_NAME;
DB_NAME肯定就是你数据库的名字啦。
谢谢,我这样写哪里有错?public class TestActivity extends Activity {
static SQLiteDatabase db;
private final static String DATABASE_PATH = android.os.Environment
.getExternalStorageDirectory().getAbsolutePath() + "/database";
private static String DATABASE_FILENAME = "chinacity.db";
private Context mContext; public TestActivity(Context context) {
// TODO Auto-generated constructor stub
this.mContext = context;
} // 使用外部数据库
public static SQLiteDatabase openDatabase(Context context) {
try {
String databaseFilename = DATABASE_PATH + "/" + DATABASE_FILENAME;
File dir = new File(DATABASE_PATH);
if (!dir.exists()) // 如果文件夹不存在创建文件夹
dir.mkdir();
if (!(new File(databaseFilename)).exists()) { // 如果文件不存在创建文件
InputStream is = context.getResources().openRawResource(
R.raw.chinacity);
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();
}
db = SQLiteDatabase.openOrCreateDatabase(databaseFilename, null); } catch (Exception e) {
e.printStackTrace();
}
return db;
} @Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
System.out.println("数据库地址" + DATABASE_PATH);
Context c = new TestActivity(mContext);
SQLiteDatabase db = TestActivity.openDatabase(c);
System.out.println("数据库为===========" + db);
}
}
这个是什么?一般在android里面使用数据库的话最好要实现一个一个继承SQLiteOpenHelper的类,用来管理数据库建立之类的。我之前实现了一个类,不过没有继承SQLiteOpenHelper,哈哈,如果可以最好是继承它啦。给你参考一下。
package com.***.***;import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.os.Environment;
import android.util.Log;public class DatabaseAdapter {
private static final String TAG = "DatabaseAdapter"; public static final int BUFFER_SIZE = 400000;
public static final String PACKAGE_NAME = "com.***.***";//你的包名
public static final String DB_PATH = "/data"+Environment.getDataDirectory().getAbsolutePath()
+"/"+PACKAGE_NAME;
public static final String CHANNEL_IDC = "channel_id";//数据库里面的列名
public static final String CHANNEL_NAME = "channel_name";//数据库里面的列名
public static final String CHANNEL_NUMBER = "channel_number";//数据库里面的列名
public static final String FREE = "free";//数据库里面的列名
public static final String TYPE_ID = "type_id";//数据库里面的列名
public static final String ADDRESS_ID = "address_id";//数据库里面的列名
public static final String URL = "url";//数据库里面的列名
public static final String URLTYPE = "urlType";//数据库里面的列名
public static final String CHANNEL_IDA = "channel_id";//数据库里面的列名
private static final String DB_NAME = "***.db";//数据库名字
private static final String DB_TABLEC = "***";//数据库里面表的名字
private static final String DB_TABLEA = "***";//数据库里面表的名字
private static final int DB_VERSION = 1;
private Context mContext = null;
private SQLiteDatabase db = null;
private String filename = DB_PATH+"/"+DB_NAME;
public DatabaseAdapter(Context context) {
mContext = context;
}
public void open()throws SQLException
{ writefromraw(filename);
db = opendatabase();
}
public SQLiteDatabase opendatabase() throws SQLException
{
db = SQLiteDatabase.openOrCreateDatabase(filename, null);
return db;
}
private void writefromraw(String dbfile) {
// TODO Auto-generated method stub
try {
if (!(new File(dbfile).exists())) {
InputStream is = mContext.getResources().openRawResource(
R.raw.livetv_database);
FileOutputStream fos = new FileOutputStream(dbfile);
byte[] buffer = new byte[BUFFER_SIZE];
int count = 0;
while ((count = is.read(buffer)) > 0) {
fos.write(buffer, 0, count);
}
fos.close();
is.close();
}
} catch (FileNotFoundException e) {
Log.e("Database", "File not found");
e.printStackTrace();
} catch (IOException e) {
Log.e("Database", "IO exception");
e.printStackTrace();
} } public String fetchData(long rowId)throws SQLException//查询DB_TABLEA里面CHANNEL_IDA等于rowId的URL数据
{
Cursor mCursor = db.query(DB_TABLEA, new String[]{URL}, CHANNEL_IDA + "=" + rowId, null, null, null, null); if (mCursor.moveToFirst())
{
String url = mCursor.getString(mCursor.getColumnIndex(URL));
mCursor.close();
return url;
}
mCursor.close();
return null;
}
public Cursor fetchAllData()//查询DB_TABLEC里面CHANNEL_IDC和CHANNEL_NAME这两列所有的数据
{
Cursor mCursor = db.query(DB_TABLEC, new String[]{CHANNEL_IDC,CHANNEL_NAME}, null, null, null, null, null);
return mCursor;
}
public void close()
{
if (db != null)
db.close();
}
}
实现了这个类之后,要使用数据库就很方便啦。先定义一个这个类的实例,然后调用它的open()方法就可以打开数据库了,然后如果你要取得里面的某一个数据的话就用fetchData这个方法,全部都取得的话就用fetchAllData的方法,当然这里方法里面你要取的列是那些就要你自己定义啦,还有fetchData里面过滤的条件也是你自己要定义啊。
还有要提醒的一点是调用open()方法在用完数据库后记得要调close()方法啊,不然会报错的。还有fetchAllData也是,Cursor对象用完也是需要close()的,fetchAllData可以参考fetchData,用法差不多的。