Question

我创建了一个sqlite数据库并将.db文件复制到应用程序的assets文件夹，如问题2605555所述。代码编译正常。在运行时，它表示无法读取文件。

我想使用readymade .db文件，并且只在不存在的情况下才想创建数据库。

需要帮助才能使用.db文件创建数据库。

Answer 1

 @Override
        public void onCreate(SQLiteDatabase db) {
    File file=new File("YOUR DBfile PATH");
    db.openOrCreateDatabase(file,null,CREATE_IF_NECESSARY);
    }

Answer 2

package com.airi.buyue.data;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Environment;

import com.airi.buyue.BuyueApp;
import com.airi.buyue.R;
import com.airi.buyue.util.FileUtils;
import com.airi.buyue.util.Utilities;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class DataManager {

    public static final String DB_NAME = "zonen.db";
    public static final String TABLE_NAME = "m_nzone_copy";

    private SQLiteDatabase database;
    private final Context context;

    public DataManager(Context context) {
        this.context = context;
        getPath();
    }

    public SQLiteDatabase getDatabase() {
        return database;
    }

    public void setDatabase(SQLiteDatabase database) {
        this.database = database;
    }

    public void openDatabase() {
        this.database = this.openDatabase(getPath() + "/" + DB_NAME);
    }

    public  String getPath(){
        String DATABASE_PATH;
        if (!Utilities.isSdcardExisting()) {
            DATABASE_PATH = BuyueApp.get().getFilesDir().getPath();
        }else{
            DATABASE_PATH = Environment.getExternalStorageDirectory().getPath();
        }
        return DATABASE_PATH;
    }

    public boolean needCreate() {
        String dbfile = getPath() + "/" + DB_NAME;
        try {
            if (!(new File(dbfile).exists())) {
                return true;
            }
            FileUtils.updateFile(dbfile);
            return false;

        }  catch (Throwable ignored) {
        }
        return true;
    }

    private SQLiteDatabase openDatabase(String dbfile) {
        try {
            if (!(new File(dbfile).exists())) {
                InputStream is = this.context.getResources().openRawResource(R.raw.zone);
                FileOutputStream fos = new FileOutputStream(dbfile);
                int BUFFER_SIZE = 400000;
                byte[] buffer = new byte[BUFFER_SIZE];
                int count = 0;
                while ((count = is.read(buffer)) > 0) {
                    fos.write(buffer, 0, count);
                }
                fos.close();
                is.close();
            }
            FileUtils.updateFile(dbfile);
            return SQLiteDatabase.openOrCreateDatabase(dbfile,null);

        } catch (FileNotFoundException ignored) {
        } catch (IOException ignored) {
        } catch (Throwable ignored) {
        }
        return null;
    }

    public void closeDatabase() {
        if(this.database!=null){
            this.database.close();
        }
    }
}

Android：从db文件创建sqlite数据库

2 个答案: