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Android中SQLite操作示例

2012-01-14 13:33 本站整理 浏览(7)
在Android中对SQLite数据库的操作,涉及以下几个方面:
1、确认数据库文件,即.db文件;
2、通过android.database.sqlite. SQLiteDatabase类的openOrCreateDatabase()方法打开数据库;
3、数据库操作:
A、开始事务: SQLiteDatabase.beginTransaction();
B、执行sql语句;
C、结束事务: SQLiteDatabase.endTransaction();
具体代码可参考如下:
Java代码





static boolean installDefaultSitesToDB(Context cxt) {
// 确认目标数据库文件
File path = cxt.getDir("databases", Context.MODE_WORLD_WRITEABLE);
path = new File(path, "db_name.db");
SQLiteDatabase db = null;
try {
// 打开数据库
db = openDB(path.getAbsolutePath());
if (db == null) {
//Log.e("tag", "open db_name.db ERROR~");
return false;
}
db.beginTransaction();//开始事务
boolean bool = doInstallData(db);//执行sql语句,插入数据
//设置事务标志
if (bool) {
db.setTransactionSuccessful();// 设置事务标志
} else {
//Log.w("tag", "doInstall.DEFAULT_SITES Fail~!");
}
return bool;
} finally {
if (db != null) {
//结束事务
if (db.inTransaction()) {db.endTransaction();}
db.close();
}
}
}
private static SQLiteDatabase openDB(String file) {
try {
//SQLiteDatabase.openOrCreateDatabase(file, null);
int flag = SQLiteDatabase.OPEN_READWRITE;
flag = flag | SQLiteDatabase.CREATE_IF_NECESSARY;
flag = flag | SQLiteDatabase.NO_LOCALIZED_COLLATORS;
SQLiteDatabase db = SQLiteDatabase.openDatabase(file, null, flag);
return db;
} catch (Throwable e) {
//Log.e("tag","openDatabase error:" + e.getMessage());
return null;
}
}
//
private static boolean doInstallData(SQLiteDatabase db) {
try {
//create table
String sql = "CREATE TABLE IF NOT EXISTS Permissions (origin TEXT UNIQUE NOT NULL, allow INTEGER NOT NULL)";
db.execSQL(sql);
ContentValues cv = new ContentValues();
for (String site : DEFAULT_SITES) {
cv.clear();
cv.put("origin", site);
cv.put("allow", 1);
long ret = db.insertOrThrow("Permissions", null, cv);
Log.d("tag", "db.insert.RET:" + ret);
}
return true;
} catch (SQLException se) {
String msg = "doInstall.error:[%s].%s";
Log.d("tag",String.format(msg, se.getClass(),se.getMessage()));
return false;
}
}