dbHelper.java
package com.terry;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.util.Log;public class dbHelper extends SQLiteOpenHelper { private final static String DATABASE_NAME="sec_db"; private final static int DATABASE_VERSION=1; private final static String TABLE_NAME="sec_pwd"; public final static String FIELD_ID="_id"; public final static String FIELD_TITLE="sec_Title"; public dbHelper(Context context) { /** * 通过构造函数来创建数据库,如果进入此函数，不存在此数据库则创建，如果存在此数据库则打开连接， * 只要进入此方法就可以用打开的连接获得getWritableDatabase()或getReadableDatabase()这两个方法。 */ super(context, DATABASE_NAME,null, DATABASE_VERSION); } /** * 一个数据库中可以包含多个表，每一条数据都存在指定的表中，要创建可以通过 execSQL 方法来执行一条 SQL 语句。 */ @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub //创建了表名为“sec_pwd” 的数据表，表内存在一个 integer 类型的主键和一个 text 类型的字段，并执行创建该表。 String sql="Create table "+TABLE_NAME+"("+FIELD_ID+" integer primary key autoincrement," +FIELD_TITLE+" text );"; db.execSQL(sql); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub String sql=" DROP TABLE IF EXISTS "+TABLE_NAME; db.execSQL(sql); onCreate(db); } /** * 查询数据 * @return */ public Cursor select() { SQLiteDatabase db=this.getReadableDatabase(); Cursor cursor=db.query(TABLE_NAME, null, null, null, null, null, " _id desc"); return cursor; } /** * 添加数据 * @param Title * @return */ public long insert(String Title) { /** * 封装了一个使用SQLite 的 insert 方法，向表中添加数据，但是insert 方法要求把数据都打包到 ContentValues 中， * ContentValue 其实可就是一个 HashTable，Key值是字段名称，Value 值是字段的值。 * 通过 ContentValues 的put 方法就可以把数据库放到 ContentValue 对象中，然后插入到表中去。 */ SQLiteDatabase db=this.getWritableDatabase(); ContentValues cv=new ContentValues(); cv.put(FIELD_TITLE, Title); long row=db.insert(TABLE_NAME, null, cv); return row; } /** * 删除数据 * @param id */ public void delete(int id) { SQLiteDatabase db=this.getWritableDatabase(); String where=FIELD_ID+"=?"; String[] whereValue={Integer.toString(id)}; db.delete(TABLE_NAME, where, whereValue); } /** * 修改数据 * @param id * @param Title */ public void update(int id,String Title) { SQLiteDatabase db=this.getWritableDatabase(); String where=FIELD_ID+"=?"; String[] whereValue={Integer.toString(id)}; ContentValues cv=new ContentValues(); cv.put(FIELD_TITLE, Title); db.update(TABLE_NAME, cv, where, whereValue); } }??这里用到了Menu做功能按钮，实例代码如下：
?package com.terry;
import android.app.Activity;import android.database.Cursor;import android.database.sqlite.SQLiteCursor;import android.os.Bundle; import android.view.Menu; import android.view.MenuItem;import android.view.View;import android.widget.AdapterView;import android.widget.EditText;import android.widget.ListAdapter;import android.widget.ListView;import android.widget.SimpleCursorAdapter;import android.widget.AdapterView.OnItemClickListener;import android.widget.AdapterView.OnItemSelectedListener;public class testDbActivity extends Activity { private dbHelper db; private Cursor myCursor; private ListView myListView; private EditText myEditText; private int _id; protected final static int MENU_ADD=Menu.FIRST; protected final static int MENU_EDIT=Menu.FIRST+1; protected final static int MENU_DELETE=Menu.FIRST+2; @Override public boolean onCreateOptionsMenu(Menu menu) { // TODO Auto-generated method stub super.onCreateOptionsMenu(menu); menu.add(Menu.NONE, MENU_ADD, 0, R.string.ADD); menu.add(Menu.NONE, MENU_EDIT, 0,R.string.EDIT); menu.add(Menu.NONE, MENU_DELETE, 0,R.string.DELETE); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // TODO Auto-generated method stub super.onOptionsItemSelected(item); switch (item.getItemId()) { case MENU_ADD: operation("add"); break; case MENU_EDIT: operation("edit"); break; case MENU_DELETE: operation("delete"); break; default: break; } return true; } /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); myEditText=(EditText)findViewById(R.id.EditText1); myListView=(ListView)findViewById(R.id.ListView1); db=new dbHelper(testDbActivity.this); myCursor=db.select(); SimpleCursorAdapter adpater=new SimpleCursorAdapter(this , R.layout.test, myCursor, new String[]{dbHelper.FIELD_TITLE}, new int[]{R.id.topTextView}); myListView.setAdapter(adpater); myListView.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub myCursor.moveToPosition(arg2); _id=myCursor.getInt(0); myEditText.setText(myCursor.getString(1)); } }); myListView.setOnItemSelectedListener(new OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub SQLiteCursor sc=(SQLiteCursor)arg0.getSelectedItem(); _id=sc.getInt(0); myEditText.setText(sc.getString(1)); } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } }); } private void operation(String cmd) { if(myEditText.getText().toString().equals("")) return; if(cmd=="add") db.insert( myEditText.getText().toString()); if(cmd=="edit") db.update(_id, myEditText.getText().toString()); if(cmd=="delete") db.delete(_id); myCursor.requery(); myListView.invalidateViews(); myEditText.setText(""); _id=0; } }?
?