[连载 5/15] Android 从入门到精通Example 之 SQLite Database Example

使用sqlite 数据库的例子

 

1. DBExample.java

public class DBExample extends Activity implements View.OnClickListener {private TextView textArea1;private EditText field1;private EditText field2;public static String newline = System.getProperty("line.separator");private SQLiteDatabase db;private static final String TAG = "DBExample";private static final String DBNAME = "sample1";private static final String TABLE1NAME = "table1";private static final String CREATE_TABLE1 = "create table if not exists "+ " table1 (id integer primary key autoincrement, "+ " text1 text not null, text2 text not null);"; /** Called when the activity is first created. */ @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main); field1 = (EditText) findViewById(R.id.field1); field2 = (EditText) findViewById(R.id.field2); Button saveButton = (Button) findViewById(R.id.button1); saveButton.setOnClickListener(this); Button deleteButton = (Button) findViewById(R.id.delbutton); deleteButton.setOnClickListener( new View.OnClickListener() { public void onClick(View v) { deleteAllRows(); } }); Button showAllButton = (Button) findViewById(R.id.showallbutton); showAllButton.setOnClickListener( new View.OnClickListener() { public void onClick(View v) { showAllValues(); } }); textArea1 = (TextView) findViewById(R.id.textarea1); openDatabase(); //insertRow("hello1", "db1"); } private void openDatabase() { try { db = openOrCreateDatabase(DBNAME, MODE_WORLD_WRITEABLE, null);db.execSQL(CREATE_TABLE1); } catch (Exception e){ Log.i(TAG, "Error opening DB or creating new DB. " + e); } } private boolean insertRow(String value1, String value2) { ContentValues values = new ContentValues(); values.put("text1", value1); values.put("text2", value2); return (db.insert(TABLE1NAME, null, values) > 0); } private boolean deleteAllRows() {textArea1.setText("Deleted All Values in Table: "+TABLE1NAME); return (db.delete(TABLE1NAME, "id>=0", null) > 0); } public List<Table1Items> getItems() { ArrayList<Table1Items> dbRows = new ArrayList<Table1Items>(); try { Cursor c = db.query(TABLE1NAME, new String[] { "id", "text1", "text2" }, null, null, null, null, null); int numRows = c.getCount(); c.moveToFirst(); for (int i = 0; i < numRows; ++i) { Table1Items item = new Table1Items(); item.id = c.getLong(0); item.text1 = c.getString(1); item.text2 = c.getString(2); dbRows.add(item); c.moveToNext(); } } catch (Exception e) { Log.e(TAG, "Error in getting items from db: " + e); } return dbRows; } /* * * clicked on button "Insert Values" * */public void onClick(View arg0) {textArea1.setText("");insertRow(field1.getText().toString(), field2.getText().toString());textArea1.append("inserted: "+field1.getText() + ", " + field2.getText().toString());field1.setText("");field2.setText("");}private void showAllValues() {textArea1.setText("");ArrayList<Table1Items> tableItems = (ArrayList<Table1Items>) getItems();for (Iterator<Table1Items> it = tableItems.iterator(); it.hasNext(); ) {Table1Items item = it.next();textArea1.append(item.toString() + newline);}}}

 

2. Table1Items.java

public class Table1Items extends Object{public long id;public String text1;public String text2;public String toString() {return ("ID: " + id + " Text1: " + text1 + " Text2: " + text2);}}