Java 如何在android中以编程方式更改文件/文件夹权限
如果正在存储应用程序数据库,我想更改文件夹的权限。 在谷歌上搜索后,我发现:-Java 如何在android中以编程方式更改文件/文件夹权限,java,android,file-permissions,chmod,fileutils,Java,Android,File Permissions,Chmod,Fileutils,如果正在存储应用程序数据库,我想更改文件夹的权限。 在谷歌上搜索后,我发现:- public int chmod(File path, int mode) throws Exception { Class fileUtils = Class.forName("android.os.FileUtils"); Method setPermissions = fileUtils.getMethod("setPermissions", String.class, int.class,
public int chmod(File path, int mode) throws Exception {
Class fileUtils = Class.forName("android.os.FileUtils");
Method setPermissions =
fileUtils.getMethod("setPermissions", String.class, int.class, int.class, int.class);
return (Integer) setPermissions.invoke(null, path.getAbsolutePath(), mode, -1, -1);
}
...
chmod("/foo/bar/baz", 0755);
...
这里的FileUtils
类应该是android.os
包的一部分,但是我在导入包时找不到它
您知道如何使用FileUtils
或其他方法更改文件夹的权限吗
我正在更改权限,因为在安装应用程序后,当我尝试访问数据库时,应用程序停止工作。由于我的设备是根目录
,因此当我使用根目录浏览器将数据库文件夹的权限从771
更改为777
时,应用程序开始正常工作。
那么,如何在安装应用程序时更改文件夹的权限,即在unrooted
设备中以编程方式
MyDBHelper
类:-
public class DBHelper extends SQLiteOpenHelper {
public SQLiteDatabase database = null;
public File databaseFile;
public static String databaseName = "Db1.sqlite";
public String databasePath = "";
Context mContext;
public DBHelper(Context paramContext) {
super(paramContext, databaseName, null, 1);
this.mContext = paramContext;
Log.d("data", "package name:" + paramContext.getPackageName());
//this.databasePath = ("data/data/" + paramContext.getPackageName() + "/databases/"+databaseName);
this.databasePath = (Environment.getExternalStorageDirectory().getAbsolutePath()+"/Android/data/"+paramContext.getPackageName()+"/"+databaseName);
System.out.println(databasePath);
this.databaseFile = new File(this.databasePath);
if (!this.databaseFile.exists())
try {
deployDataBase(DBHelper.databaseName, this.databasePath);
return;
} catch (IOException localIOException) {
localIOException.printStackTrace();
}
}
private void deployDataBase(String dbNAme, String dbPath)
throws IOException {
InputStream localInputStream = this.mContext.getAssets().open(dbNAme);
FileOutputStream localFileOutputStream = new FileOutputStream(dbPath);
byte[] arrayOfByte = new byte[1024];
while (true) {
int i = localInputStream.read(arrayOfByte);
if (i <= 0) {
localFileOutputStream.flush();
localFileOutputStream.close();
localInputStream.close();
return;
}
localFileOutputStream.write(arrayOfByte, 0, i);
}
}
@Override
public synchronized void close() {
if (database != null)
database.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
public类DBHelper扩展了SQLiteOpenHelper{
公共SQLiteDatabase=null;
公共文件数据库文件;
公共静态字符串databaseName=“Db1.sqlite”;
公共字符串databasePath=“”;
语境;
公共DBHelper(上下文参数上下文){
super(paramContext,databaseName,null,1);
this.mContext=paramContext;
Log.d(“数据”,“包名:”+paramContext.getPackageName());
//this.databasePath=(“data/data/”+paramContext.getPackageName()+“/databases/”+databaseName);
this.databasePath=(Environment.getExternalStorageDirectory().getAbsolutePath()+“/Android/data/”+paramContext.getPackageName()+“/”+databaseName);
System.out.println(数据库路径);
this.databaseFile=新文件(this.databasePath);
如果(!this.databaseFile.exists())
试一试{
部署数据库(DBHelper.databaseName,this.databasePath);
返回;
}捕获(IOException localIOException){
localIOException.printStackTrace();
}
}
私有数据库(字符串dbNAme、字符串dbPath)
抛出IOException{
InputStream LocaliInputStream=this.mContext.getAssets().open(dbNAme);
FileOutputStream localFileOutputStream=新的FileOutputStream(dbPath);
字节[]数组字节=新字节[1024];
while(true){
int i=localInputStream.read(arrayOfByte);
如果(i
- 不要使用您案例的db路径和文件权限
- IMO和普通设备是相互排斥的受众
- 仅用于测试根设备,在sd卡上创建db,路径派生自Environment.getExternalStorage**方法
要在SD卡上安装数据库,请执行以下操作
将该类放入代码包中
package com.test.db;
import java.io.File;
import android.content.Context;
import android.content.ContextWrapper;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.os.Environment;
/**
* Custom context wrapper to proxy the database file path.
* Instead of storing data on internal storage for app
* we will storing the data on external sd card.
*/
public class DatabaseContext extends ContextWrapper {
/*
* Used for logging.
*/
private static final String DEBUG_CONTEXT = "DatabaseContext";
/*
* Constructor wrapping given app context.
*/
public DatabaseContext(Context base) {
super(base);
}
/**
* Proxy the path to data base file for every operation
* @see android.content.ContextWrapper#getDatabasePath(java.lang.String)
*/
@Override
public File getDatabasePath(String name) {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// We can read and write the media
File sdcard = Environment.getExternalStorageDirectory();
String dbfile = sdcard.getAbsolutePath() + File.separator + "com.test" + File.separator + "database" + File.separator
+ name;
if (!dbfile.endsWith(".db")) {
dbfile += ".db";
}
File result = new File(dbfile);
if (!result.getParentFile().exists()) {
if(!result.getParentFile().mkdirs()){
result = new File(sdcard, name);
}
}
if (android.util.Log.isLoggable(DEBUG_CONTEXT, android.util.Log.WARN)) {
android.util.Log.w(DEBUG_CONTEXT,
"getDatabasePath(" + name + ") = " + result.getAbsolutePath());
}
return result;
} else {
// Something else is wrong. It may be one of many other states,
// Writing data on internal storage
return super.getDatabasePath(name);
}
}
@Override
public SQLiteDatabase openOrCreateDatabase(String name, int mode,
CursorFactory factory) {
return openOrCreateDatabase(name, mode, factory, null);
}
@Override
public SQLiteDatabase openOrCreateDatabase(String name, int mode, CursorFactory factory,
DatabaseErrorHandler errorHandler) {
SQLiteDatabase result = SQLiteDatabase.openOrCreateDatabase(getDatabasePath(name)
.getAbsolutePath(), null, errorHandler);
return result;
}
}
像这样扩展SqliteOpenHelper类
package com.test.db;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
/**
* Custom SqliteOpenHelper.
*/
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
private static final String TAG = My.class.getSimpleName();
private final Context context;
public MySQLiteOpenHelper(Context context, String name, int version, String mResourceName) {
super(new DatabaseContext(context), name, /*factory*/null, version);
this.context = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
// Create tables here
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
这是在sd卡中创建db的测试件。请检查您正在玩一个危险的游戏。@SotiriosDelimanolis但如果我不这样做,我如何解决我的问题?您的db没有在外部sd卡中定义?@Javanator如果设备没有外部sd卡怎么办?现在大多数设备没有外部存储插槽,但有ex内部存储作为内部存储的模拟分区我使用了Environment.getExternalStorageDirectory().getAbsolutePath()+“/Android/data/”+paramContext.getPackageName()+“/”+databaseName
作为存储我的db
的路径,但我在那里看不到它:(在此处打印完整路径/storage/sdcard/Android/data/com.test/Db1.sqlite应用程序出现异常:-java.io.FileNotFoundException:/storage/sdcard/Android/data/com.test/Db1.sqlite:open failed:enoint(没有此类文件或目录)
因为那里没有文件。你必须创建它。检查上面的代码段。它会帮你完成。