【发布时间】：2014-03-27 23:52:09
【问题描述】：
我是 android 编程新手，所以请帮助我... 我已经使用 SQLite 数据库浏览器创建了 mydatabase.sqlite 数据库文件，并将其复制到 android 应用程序的 assets 文件夹中，以便从数据库文件中检索数据。
我想在按钮单击时显示数据库表中的所有记录并在列表视图中显示结果。
这里是代码
这是我的数据库助手类
public class DataBaseHelper extends SQLiteOpenHelper
{
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = "";
private static String DB_NAME ="datacoba";// Database name
private SQLiteDatabase mDataBase;
private final Context mContext;
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, 1);// 1? its Database Version
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
this.mContext = context;
}
public void createDataBase() throws IOException
{
//If database not exists copy it from the assets
boolean mDataBaseExist = checkDataBase();
if(!mDataBaseExist)
{
this.getReadableDatabase();
this.close();
try
{
//Copy the database from assests
copyDataBase();
Log.e(TAG, "createDatabase database created");
}
catch (IOException mIOException)
{
throw new Error("ErrorCopyingDataBase");
}
}
}
//Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
File dbFile = new File(DB_PATH + DB_NAME);
//Log.v("dbFile", dbFile + " "+ dbFile.exists());
return dbFile.exists();
}
//Copy the database from assets
private void copyDataBase() throws IOException
{
InputStream mInput = mContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer))>0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
mOutput.close();
mInput.close();
}
//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
String mPath = DB_PATH + DB_NAME;
//Log.v("mPath", mPath);
mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
//mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return mDataBase != null;
}
@Override
public synchronized void close()
{
if(mDataBase != null)
mDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
这个实用程序类
public class Utility {
public static String GetColumnValue(Cursor cur, String ColumnName) {
try {
return cur.getString(cur.getColumnIndex(ColumnName));
} catch (Exception ex) {
return "";
}
}
public static void ShowMessageBox(Context cont, String msg) {
Toast toast = Toast.makeText(cont, msg, Toast.LENGTH_SHORT);
// toast.setGravity(Gravity.CENTER, 0, 0);
toast.setGravity(Gravity.CENTER | Gravity.CENTER, 0, 0);
toast.show();
}
}
这个适配器类
public class TestAdapter
{
protected static final String TAG = "DataAdapter";
private final Context mContext;
private SQLiteDatabase mDb;
private DataBaseHelper mDbHelper;
public TestAdapter(Context context)
{
this.mContext = context;
mDbHelper = new DataBaseHelper(mContext);
}
public TestAdapter createDatabase() throws SQLException
{
try
{
mDbHelper.createDataBase();
}
catch (IOException mIOException)
{
Log.e(TAG, mIOException.toString() + " UnableToCreateDatabase");
throw new Error("UnableToCreateDatabase");
}
return this;
}
public TestAdapter open() throws SQLException
{
try
{
mDbHelper.openDataBase();
mDbHelper.close();
mDb = mDbHelper.getReadableDatabase();
}
catch (SQLException mSQLException)
{
Log.e(TAG, "open >>"+ mSQLException.toString());
throw mSQLException;
}
return this;
}
public void close()
{
mDbHelper.close();
}
public Cursor getTestData()
{
try
{
String sql ="SELECT Nama_student From Nama";
Cursor mCur = mDb.rawQuery(sql, null);
if (mCur!=null)
{
mCur.moveToNext();
}
return mCur;
}
catch (SQLException mSQLException)
{
Log.e(TAG, "getTestData >>"+ mSQLException.toString());
throw mSQLException;
}
}
}
这是我的 MainActivity 类
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void LoadEmployee(View v)
{
TestAdapter mDbHelper = new TestAdapter(this);
mDbHelper.createDatabase();
mDbHelper.open();
Cursor testdata = mDbHelper.getTestData();
String name = Utility.GetColumnValue(testdata, "Nama_student");
Utility.ShowMessageBox(this, "Name: "+ name);
mDbHelper.close();
}
}
代码产生由 toast 显示的输出，例如 this 并且只显示了表格的第一行。 如何显示表中的所有行并在列表视图中显示结果？ 编辑：这是我的 xml 布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/btnSearch"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="14dp"
android:layout_marginTop="19dp"
android:onClick="LoadEmployee"
android:text="Load Employee"
/>
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/btnSearch"
android:layout_below="@+id/btnSearch"
android:layout_marginLeft="21dp"
android:layout_marginTop="166dp" >
</ListView>
【问题讨论】：
-
也许你应该先问问谷歌。可能有很多教程。
标签： android sql database sqlite listview