如果读取资源文件assets 中的db文件

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将db文件先保存到手机上，操作如下：

package com.ssyw.exam2.util;import java.io.File;import java.io.FileOutputStream;import java.io.InputStream;import android.content.Context;import android.content.res.AssetManager;import android.database.sqlite.SQLiteDatabase;import android.os.Environment;public class DBUtil {   private Context context;   private final int BUFFER_SIZE = 1024;   // 保存的数据库文件名 与 DBHelper 统一   private static final String DB_NAME ="data.db";    private final String PACKAGE_NAME;// 包名   private final String DB_PATH; // 在手机里存放数据库的位置   public DBUtil(Context context) {      this.context = context;      PACKAGE_NAME = PackageUtil.getAppInfo(context).getAsString(            "packageName");      DB_PATH = "/data" + Environment.getDataDirectory().getAbsolutePath()            + "/" + PACKAGE_NAME + "/databases/"; // 在手机里存放数据库的位置   }   public void openDatabase() {      File dir = new File(DB_PATH);      if (!dir.exists()) {         dir.mkdir();      }      File db_file = new File(DB_PATH, DB_NAME);      if (!db_file.exists()) {         AssetManager am = context.getAssets();         try {            InputStream is = am.open(DB_NAME);            FileOutputStream fos = new FileOutputStream(db_file);            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 (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();         } // 欲导入的数据库      }   }}

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