Android 如何导入已有的外部数据库

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.os.Environment;

import android.util.Log;

public class DBManager {

private final int BUFFER_SIZE = 400000;

public static final String DB_NAME = "countries.db"; //保存的数据库文件名

public static final String PACKAGE_NAME = "com.android.ImportDatabase";

public static final String DB_PATH = "/data"+ Environment.getDataDirectory().getAbsolutePath() + "/"+ PACKAGE_NAME; //在手机里存放数据库的位置

private SQLiteDatabase database;

private Context context;

DBManager(Context context) {

this.context = context;

}

public void openDatabase() {

this.database = this.openDatabase(DB_PATH + "/" + DB_NAME);

}

private SQLiteDatabase openDatabase(String dbfile) {

try {

if (!(new File(dbfile).exists())) {　　//判断数据库文件是否存在，若不存在则执行导入，否则直接打开数据库

InputStream is = this.context.getResources().openRawResource(

R.raw.countries); //欲导入的数据库

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();

}

SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile,null);

return db;

} catch (FileNotFoundException e) {

　　Log.e("Database", "File not found");

　　 e.printStackTrace();

} catch (IOException e) {

　　Log.e("Database", "IO exception");

　　e.printStackTrace();

}

　　return null;

}

然后在程序的首个**Activity**中示例化一个**DBManager**对象，然后对其执行**openDatabase**方法就可以完成导入了，可以把一些要对数据库进行的操作写在**DBManager类**里，然后通过**DBManager**类的对象调用；也可以在完成导入之后通过一个**SQliteDatabase类**的对象打开数据库，并执行操作。  

  

我的做法是 在程序的首个**Activity**中导入数据库：

package EOE.android.ImportDatabase;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

public class RootView extends Activity {

public DBManager dbHelper;

我们在需要使用数据库的类里：

package eoe.android.ImportDatabase;

import java.util.ArrayList;

import android.app.Activity;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

public class TaxiActivity extends Activity {

private SQLiteDatabase database;

ArrayList CITY;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

database = SQLiteDatabase.openOrCreateDatabase(DBManager.DB_PATH + "/" + DBManager.DB_NAME, null);

CITY = getCity();

// 做一些事情时

database.close();

}

private ArrayList getCity() {

Cursor cur = database.rawQuery("SELECT city.id_city, city.name FROM taxi, city WHERE city.id_city = taxi.id_city GROUP BY city.id_city", null);

if (cur != null) {

int NUM_CITY = cur.getCount();

ArrayList taxicity = new ArrayList(NUM_CITY);

if (cur.moveToFirst()) {

do {

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

int id = cur.getInt(cur.getColumnIndex("id_city"));