Android:自定义Sqlite数据库路径

默认的sqlite数据库是放在/data/data/database目录下的，今天看腾讯云IM的demo发现再该路径下找不到它存放消息的数据库，找了下后发现居然是放在/data/data/files目录下的，虽然不知道为什么要放到这个目录，不过仔细想了下突然发觉假如把数据库放到非data目录下的话，就可以不借助contentprovider之类的方式实现跨应用访问数据库了，虽然安全性会降低，但在部分场景下还是会有所作用的。

阅读下了SqliteOpenHelper的源码，和数据库路径相关部分如下。

public SQLiteDatabase getWritableDatabase() {
synchronized (this) {
return getDatabaseLocked(true);
}
}

public SQLiteDatabase getReadableDatabase() {
synchronized (this) {
return getDatabaseLocked(false);
}
}

private SQLiteDatabase getDatabaseLocked(boolean writable) {
if (mDatabase != null) {
if (!mDatabase.isOpen()) {
// Darn!  The user closed the database by calling mDatabase.close().
mDatabase = null;
} else if (!writable || !mDatabase.isReadOnly()) {
// The database is already open for business.
return mDatabase;
}
}

if (mIsInitializing) {
throw new IllegalStateException("getDatabase called recursively");
}

SQLiteDatabase db = mDatabase;
try {
mIsInitializing = true;

if (db != null) {
if (writable && db.isReadOnly()) {
db.reopenReadWrite();
}
} else if (mName == null) {
db = SQLiteDatabase.create(null);
} else {
try {
if (DEBUG_STRICT_READONLY && !writable) {
String path = mContext.getDatabasePath(mName).getPath()
db = SQLiteDatabase.openDatabase(path, mFactory,
SQLiteDatabase.OPEN_READONLY, mErrorHandler);
} else {
db = mContext.openOrCreateDatabase(mName, mEnableWriteAheadLogging ?
Context.MODE_ENABLE_WRITE_AHEAD_LOGGING : 0,
mFactory, mErrorHandler);
}
} catch (SQLiteException ex) {
if (writable) {
throw ex;
}
Log.e(TAG, "Couldn't open " + mName
+ " for writing (will try read-only):", ex);
final String path = mContext.getDatabasePath(mName).getPath();
db = SQLiteDatabase.openDatabase(path, mFactory,
SQLiteDatabase.OPEN_READONLY, mErrorHandler);
}
}
........

　　其实是调用了mContext的getDataBasePath方法，这个方法是在ContextImpl中实现的，再看下源码

@Override
public File getDatabasePath(String name) {
return validateFilePath(name, false);
}

private File validateFilePath(String name, boolean createDirectory) {
File dir;
File f;

if (name.charAt(0) == File.separatorChar) {
String dirPath = name.substring(0, name.lastIndexOf(File.separatorChar));
dir = new File(dirPath);
name = name.substring(name.lastIndexOf(File.separatorChar));
f = new File(dir, name);
} else {
dir = getDatabasesDir();
f = makeFilename(dir, name);
}

if (createDirectory && !dir.isDirectory() && dir.mkdir()) {
FileUtils.setPermissions(dir.getPath(),
FileUtils.S_IRWXU|FileUtils.S_IRWXG|FileUtils.S_IXOTH,
-1, -1);
}

return f;
}

好吧，原来这么简单，原来Android本身已经实现了自定义路径的方法了，只要传入的path的第一个字符为"/"就行了。

总结下就一句话，只要传入自定义路径的完整路径就好了。。。。