AndroidStudio下读取assets下db文件报错

[CaptainXero]

Hi，以下问题困扰我很久，求大神们不吝赐教！
首先我是用的IDE是AndroidStudio 1.5.1 ，API 23 （Android 6.0）
在读取assets下的db文件时出现问题，以下是我的相关代码以及报错提示：

ublic class AntiVirusDao {
    private static String DB_PATH = "";
    private static String DB_NAME = "antivirus.db";
    public static String checkVirus(String md5,Context context){
        String desc = null;
        /**打开病毒MD5数据库*/
        SQLiteDatabase db = SQLiteDatabase.openDatabase
                (DB_PATH = context.getApplicationInfo().dataDir + "/"+DB_NAME,null,SQLiteDatabase.OPEN_READWRITE);
        Cursor cursor = db.rawQuery("select desc from datable where md5=?",new String[]{md5});
        if(cursor.moveToNext()){
            desc = cursor.getString(0);
        }
        cursor.close();
        db.close();
        return desc;
    }

new Thread(){
            public void run(){
                Message msg = Message.obtain();
                msg.what = SCAN_BEGIN;
                myHandler.sendMessage(msg);//sengEmptyMessage只能存放整形数据,sendMessage可以存放其他类型
                List<PackageInfo> installedPackage = pm.getInstalledPackages(0);
                total = installedPackage.size();
                for(PackageInfo info : installedPackage){
                    if(!flag){
                        isStop = true;
                        return;
                    }
                    String apkpath = info.applicationInfo.sourceDir;
                    String md5info = MD5Utils.getFileMD5(apkpath);
//                    context = getApplicationContext();
                    String result = AntiVirusDao.checkVirus(md5info,mcontext);
                    msg = Message.obtain();
                    msg.what = SCANNING;
                    ScanAppInfo scanAppInfo = new ScanAppInfo();
                    if(result==null){
                        scanAppInfo.description = "您的手机安全";
                        scanAppInfo.isVirus = false;
                    }else {
                        scanAppInfo.description = result;
                        scanAppInfo.isVirus = true;
                    }
                    process++;
                    scanAppInfo.packageName = info.packageName;
                    scanAppInfo.appName = info.applicationInfo.loadLabel(pm).toString();
                    msg.obj = scanAppInfo;
                    msg.arg1 = process;
                    myHandler.sendMessage(msg);
                    try{
                        Thread.sleep(300);
                    }catch (InterruptedException e){
                        e.printStackTrace();
                    }
                }
                msg = Message.obtain();
                msg.what = SCAN_FINISH;
                myHandler.sendMessage(msg);
            };
        }.start();
    }

[jklwan]

读取assets下的文件用InputStream is = getAssets().open("文件名");

[CaptainXero]

引用 1 楼 jklwan 的回复:

读取assets下的文件用InputStream is = getAssets().open("文件名");

Hi，感谢你的回答，请问能否针对我这个写几行代码我看一下，因为还不是很清楚。谢谢

[jklwan]

引用 2 楼 CaptainXero 的回复:

Hi，感谢你的回答，请问能否针对我这个写几行代码我看一下，因为还不是很清楚。谢谢

想要使用assets下的db数据库，你需要把文件拷贝到你知道的目录下，然后再读取，参考代码

private void copyDataBase() throws IOException{
 
    	//Open your local db as the input stream
    	InputStream myInput = myContext.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;
 
    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];
    	int length;
    	while ((length = myInput.read(buffer))>0){
    		myOutput.write(buffer, 0, length);
    	}
 
    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }

拷贝完毕以后就可以用SQLiteDatabase去读取DB_PATH + DB_NAME的数据库了。

[CaptainXero]

引用 3 楼 jklwan 的回复:

[quote=引用 2 楼 CaptainXero 的回复:] Hi，感谢你的回答，请问能否针对我这个写几行代码我看一下，因为还不是很清楚。谢谢

想要使用assets下的db数据库，你需要把文件拷贝到你知道的目录下，然后再读取，参考代码

private void copyDataBase() throws IOException{
 
    	//Open your local db as the input stream
    	InputStream myInput = myContext.getAssets().open(DB_NAME);
 
    	// Path to the just created empty db
    	String outFileName = DB_PATH + DB_NAME;
 
    	//Open the empty db as the output stream
    	OutputStream myOutput = new FileOutputStream(outFileName);
 
    	//transfer bytes from the inputfile to the outputfile
    	byte[] buffer = new byte[1024];
    	int length;
    	while ((length = myInput.read(buffer))>0){
    		myOutput.write(buffer, 0, length);
    	}
 
    	//Close the streams
    	myOutput.flush();
    	myOutput.close();
    	myInput.close();
 
    }

拷贝完毕以后就可以用SQLiteDatabase去读取DB_PATH + DB_NAME的数据库了。[/quote] 谢谢您的回答，对我非常有帮助。请问这个DB_PATH是我随意指定？我自己声明一个路径？ 比如我自己定义 String DB_PATH = “/data/data/com.example.administrator.security/databases/” 然后去读 DB_PATH+“antivirus.db” 这样对么？新手，望不吝赐教

[CaptainXero]

引用 2 楼 CaptainXero 的回复:

[quote=引用 1 楼 jklwan 的回复:] 读取assets下的文件用InputStream is = getAssets().open("文件名");

Hi，感谢你的回答，请问能否针对我这个写几行代码我看一下，因为还不是很清楚。谢谢[/quote] 谢谢，我突然明白了，问题解决了，感谢！