我的 SQLite 数据库没有保留以前存储的数据。为此我遇到了很大的麻烦。我还没有找到任何合适的解决方案。请有人帮我解决这个问题。我想在应用程序重新启动后存储我的数据。我正在发布我的 DBhelper 类和 Main Method。请帮助。我想保留数据。这是我的 DBhelper 类。
我的 DBHelper 类：
public class DBhelper extends SQLiteOpenHelper {
private static String DB_NAME = "photodb";
private SQLiteDatabase myDataBase;
private DBhelper db;
public Context myContext;
File dbFile;
File dbFilepath;
AssetManager myassest;
AssetFileDescriptor me;
Cursor ch;
public DBhelper(Context myContext) {
super(myContext, DB_NAME, null, 1);
this.myContext = myContext;
System.out.println("Context value:--"+myContext);
String state=Environment.getExternalStorageState();
System.out.println("My Storage State:-"+state);
}
public void createDataBase(Context mycontext) throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
System.out.println("Yes");
String path = dbFile.getAbsolutePath();
System.out.println("My database Path:--"+path);
}
if(!dbExist)
{
dbFile= new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"PhotoApp");
boolean flag=dbFile.mkdir();
dbFilepath = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"PhotoApp"+"/"+"photodb");
dbFilepath.createNewFile();
System.out.println("Not..."+flag);
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
public boolean checkDataBase()
{
dbFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"photodb");
return dbFile.exists();
}
private void copyDataBase() throws IOException{
InputStream myInput = myContext.getAssets().open("photodb");
String outFileName = dbFilepath.getAbsolutePath();
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
String myPath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"PhotoApp"+"/"+"photodb" ;
System.out.println("MY DATABASE PATH:----"+myPath);
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public synchronized SQLiteDatabase getWritableDatabase() {
return super.getWritableDatabase();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void add(String imagepath,String description,String location)
{
long rowid;
ContentValues myvalue = new ContentValues();
myvalue.put("imagepath",imagepath);
myvalue.put("description", description);
myvalue.put("location", location);
System.out.println("My Image Path:-"+imagepath+"My Description:--"+description+"My location:--"+location);
String sql = "insert into photodetails values(null,'"+imagepath+"','"+description+"','"+location+"');";
myDataBase.execSQL(sql);
rowid = myDataBase.insert("photodetails", "id", myvalue);
System.out.println("My Row ID is:----"+rowid);
System.out.println("DB Updated");
}
public ArrayList<String> getimages(){
ch = myDataBase.rawQuery("select imagepath from photodetails" , null);
ArrayList <String> imageloc = new ArrayList<String>();
if(ch.getCount() > 0){
ch.moveToFirst();
do
{
imageloc.add(ch.getString(0));
}while(ch.moveToNext());
}
return imageloc;
}
public ArrayList<String> getDescriptions(){
ch = myDataBase.rawQuery("select description from photodetails" , null);
ArrayList <String> des = new ArrayList<String>();
if(ch.getCount() > 0){
ch.moveToFirst();
do
{
des.add(ch.getString(0));
}while(ch.moveToNext());
}
return des;
}
public ArrayList<String> getLocations(){
ch = myDataBase.rawQuery("select location from photodetails" , null);
ArrayList <String> local = new ArrayList<String>();
if(ch.getCount() > 0){
ch.moveToFirst();
do
{
local.add(ch.getString(0));
}while(ch.moveToNext());
}
return local;
}
}
这是我的主要活动：
public class MainActivity extends Activity {
DBhelper mydb;
Context cont;
ArrayList<String> myval = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mydb = new DBhelper(MainActivity.this);
try {
mydb.createDataBase(MainActivity.this);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
mydb.openDataBase();
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
mydb.add("helloworld", "Done", "Yes");
myval = mydb.getimages();
int i=myval.size();
System.out.println("SIze:----"+i);
finish();
// mydb.openDataBase();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}