我修改了我的sqliteopenhelper类，如下所示：
public class openingclass extends SQLiteOpenHelper
{
public openingclass(Context c) {
super(c,Db_NAME, null, DB_VERSION);
}
public void createDataBase() {
boolean dbExist;
try {
dbExist = checkDataBase();
} catch (SQLiteException e) {
e.printStackTrace();
throw new Error("database dose not exist");
}
if(dbExist){
//do nothing - database already exist
}else{
try {
copyDataBase();
} catch (IOException e) {
e.printStackTrace();
throw new Error("Error copying database");
}
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH +"/"+ Db_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database does't exist yet.
throw new Error("database does't exist yet.");
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//copyDataBase();
//Open your local db as the input stream
InputStream myInput = c1.getAssets().open(Db_NAME);
// Path to the just created empty db
String outFileName = DB_PATH +"/"+ Db_NAME;
File databaseFile = new File(DB_PATH);
// check if databases folder exists, if not create one and its subfolders
if (!databaseFile.exists()){
databaseFile.mkdir();
}
//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();
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase arg0) {
String S = "create table " +
TABLE_NAME +
" (" +
TABLE_COL_MAIL + " text primary key," +
TABLE_COL_NAME + " text," +
TABLE_COL_PASS + " text," +
TABLE_COL_PHO + " text," +
TABLE_COL_ADD + " text," +
TABLE_COL_GEN + " text," +
TABLE_COL_DOB + " text" +
");";
arg0.execSQL(S);
String S1 = "create table " +
SECOND_TABLE_NAME +
" (" +
TABLE_COL_USER + " text," +
TABLE_COL_PRODUCT + " text," +
TABLE_COL_QUANTITY + " integer" +
");";
arg0.execSQL(S1);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}
我在类级别添加了数据库的名称和路径，如下所示：
private final String DB_PATH="/data/data/com.example.shopkart/databases/";
private final String Db_NAME = "dbshopkart.db";
路径不正确，因为应用程序无法在设备上看到正在运行的数据库.LOGCAT如下：
05-02 15:35:20.367: E/AndroidRuntime(7848): FATAL EXCEPTION: main
05-02 15:35:20.367: E/AndroidRuntime(7848): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shopkart/com.example.shopkart.MainActivity}: android.database.sqlite.SQLiteException: no such table: products: , while compiling: SELECT NAME from products
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.os.Handler.dispatchMessage(Handler.java:99)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.os.Looper.loop(Looper.java:130)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread.main(ActivityThread.java:3689)
05-02 15:35:20.367: E/AndroidRuntime(7848): at java.lang.reflect.Method.invokeNative(Native Method)
05-02 15:35:20.367: E/AndroidRuntime(7848): at java.lang.reflect.Method.invoke(Method.java:507)
05-02 15:35:20.367: E/AndroidRuntime(7848): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
05-02 15:35:20.367: E/AndroidRuntime(7848): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
05-02 15:35:20.367: E/AndroidRuntime(7848): at dalvik.system.NativeStart.main(Native Method)
05-02 15:35:20.367: E/AndroidRuntime(7848): Caused by: android.database.sqlite.SQLiteException: no such table: products: , while compiling: SELECT NAME from products
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteCompiledSql.compile(SQLiteCompiledSql.java:92)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:65)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:83)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:49)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:42)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1358)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1326)
05-02 15:35:20.367: E/AndroidRuntime(7848): at com.example.shopkart.datamanager.retrieveproducts(datamanager.java:218)
05-02 15:35:20.367: E/AndroidRuntime(7848): at com.example.shopkart.MainActivity.onCreate(MainActivity.java:54)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-02 15:35:20.367: E/AndroidRuntime(7848): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
05-02 15:35:20.367: E/AndroidRuntime(7848): ... 11 more
我发了这么多次，问题似乎是硬编码路径。有人能告诉我如何设置路径吗？
答案 0 :(得分：0)
你在哪里调用createDatabase（）？
尝试将此方法放在构造函数中。这样，当你创建一个opensClass的对象时，它必须在使用它之前创建数据库。
public openingclass(Context c) {
super(c,Db_NAME, null, DB_VERSION);
createDataBase();
}