一个简单通过SQLite 执行CRUD 的列表展示和编辑程序。

数据操作类

import java.util.Calendar; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper;

public class DiaryDbAdapter {

    //数据库名表名     private static final String DATABASE_NAME = "database";     private static final String DATABASE_TABLE = "diary";     private static final int DATABASE_VERSION = 1;         //字段属性     public static final String KEY_TITLE = "title";     public static final String KEY_BODY = "body";     public static final String KEY_ROWID = "_id";     public static final String KEY_CREATED = "created";     //操作对象     private DatabaseHelper mDbHelper;     //数据库本身     private SQLiteDatabase mDb;

    //建库语句     private static final String DATABASE_CREATE = "create table diary (_id integer primary key autoincrement, "             + "title text not null, body text not null, created text not null);";

    //上下文对象     private final Context mCtx;

    private static class DatabaseHelper extends SQLiteOpenHelper {

        DatabaseHelper(Context context) {             super(context, DATABASE_NAME, null, DATABASE_VERSION);         }         //自动执行         @Override         public void onCreate(SQLiteDatabase db) {             db.execSQL(DATABASE_CREATE);         }

        @Override         public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {             db.execSQL("DROP TABLE IF EXISTS diary");             onCreate(db);         }     }

    //构造函数，初始化上下文     public DiaryDbAdapter(Context ctx) {         this.mCtx = ctx;     }

    public DiaryDbAdapter open() throws SQLException {         mDbHelper = new DatabaseHelper(mCtx);         mDb = mDbHelper.getWritableDatabase(); //获得一个可写数据库         return this;     }     //关闭数据库操作类     public void closeclose() {         mDbHelper.close();     }

    //添加一条记录     public long createDiary(String title, String body) {         ContentValues initialValues = new ContentValues();         initialValues.put(KEY_TITLE, title);         initialValues.put(KEY_BODY, body);         Calendar calendar = Calendar.getInstance();         String created = calendar.get(Calendar.YEAR) + "年"                 + calendar.get(Calendar.MONTH) + "月"                 + calendar.get(Calendar.DAY_OF_MONTH) + "日"                 + calendar.get(Calendar.HOUR_OF_DAY) + "时"                 + calendar.get(Calendar.MINUTE) + "分";         initialValues.put(KEY_CREATED, created);         return mDb.insert(DATABASE_TABLE, null, initialValues);     }

    //删除一条记录     public boolean deleteDiary(long rowId) {

        return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;     }

    //获得所有数据并返回Cursor     public Cursor getAllNotes() {

        return mDb.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_TITLE,                 KEY_BODY, KEY_CREATED }, null, null, null, null, null);     }

    //获得一条数据，返回也是Cursor     public Cursor getDiary(long rowId) throws SQLException {

        Cursor mCursor =

        mDb.query(true, DATABASE_TABLE, new String[] { KEY_ROWID, KEY_TITLE,                 KEY_BODY, KEY_CREATED }, KEY_ROWID + "=" + rowId, null, null,                 null, null, null);         if (mCursor != null) {             mCursor.moveToFirst();         }         return mCursor;

    }

    //更新     public boolean updateDiary(long rowId, String title, String body) {         ContentValues args = new ContentValues();         args.put(KEY_TITLE, title);         args.put(KEY_BODY, body);         Calendar calendar = Calendar.getInstance();         String created = calendar.get(Calendar.YEAR) + "年"                 + calendar.get(Calendar.MONTH) + "月"                 + calendar.get(Calendar.DAY_OF_MONTH) + "日"                 + calendar.get(Calendar.HOUR_OF_DAY) + "时"                 + calendar.get(Calendar.MINUTE) + "分";         args.put(KEY_CREATED, created);

        return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;     } }

List 页面

import android.app.ListActivity; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.ListView; import android.widget.SimpleCursorAdapter;

/** * @author jinyan * */ public class ActivityMain extends ListActivity {     private static final int ACTIVITY_CREATE = 0;     private static final int ACTIVITY_EDIT = 1;

    private static final int INSERT_ID = Menu.FIRST;     private static final int DELETE_ID = Menu.FIRST + 1;

    private DiaryDbAdapter mDbHelper; //定义数据操作类，这个类在一个新的Java文件中定义     private Cursor mDiaryCursor; //数据存储集合

    @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.diary_list);         mDbHelper = new DiaryDbAdapter(this); //初始化数据对象         mDbHelper.open(); //打开将进行初始化，实例化一个数据库         renderListView(); //刷新ListView

    }

    private void renderListView() {         mDiaryCursor = mDbHelper.getAllNotes();         startManagingCursor(mDiaryCursor); //让数据被托管，这样可以垃圾回收         String[] from = new String[] { DiaryDbAdapter.KEY_TITLE,                 DiaryDbAdapter.KEY_CREATED };//数据字段         int[] to = new int[] { R.id.text1, R.id.created }; //List控件 Id         SimpleCursorAdapter notes = new SimpleCursorAdapter(this,                 R.layout.diary_row, mDiaryCursor, from, to); //绑定Cousor对象到List         setListAdapter(notes); //绑定当前List 数据     }

    //重写草组偶菜单方法，建立菜单。     @Override     public boolean onCreateOptionsMenu(Menu menu) {         super.onCreateOptionsMenu(menu);         menu.add(0, INSERT_ID, 0, R.string.menu_insert);         menu.add(0, DELETE_ID, 0, R.string.menu_delete);         return true;     }

    //菜单选择事件     @Override     public boolean onMenuItemSelected(int featureId, MenuItem item) {         switch (item.getItemId()) {         case INSERT_ID:             createDiary();             return true;         case DELETE_ID:             mDbHelper.deleteDiary(getListView().getSelectedItemId());             renderListView();             return true;         }         return super.onMenuItemSelected(featureId, item);     }

    //插入事件代码，就是一个跳转     private void createDiary() {         Intent i = new Intent(this, ActivityDiaryEdit.class);         startActivityForResult(i, ACTIVITY_CREATE);     }

    @Override     // 需要对position和id进行一个很好的区分     // position指的是点击的这个ViewItem在当前ListView中的位置     // 每一个和ViewItem绑定的数据，肯定都有一个id，通过这个id可以找到那条数据。     protected void onListItemClick(ListView l, View v, int position, long id) {         super.onListItemClick(l, v, position, id);         Cursor c = mDiaryCursor; //定义一个临时变量         c.moveToPosition(position); //         Intent i = new Intent(this, ActivityDiaryEdit.class); //跳转到编辑页面         //写入参数         i.putExtra(DiaryDbAdapter.KEY_ROWID, id); //ID可以作为参数传进来         i.putExtra(DiaryDbAdapter.KEY_TITLE, c.getString(c                 .getColumnIndexOrThrow(DiaryDbAdapter.KEY_TITLE)));         i.putExtra(DiaryDbAdapter.KEY_BODY, c.getString(c                 .getColumnIndexOrThrow(DiaryDbAdapter.KEY_BODY)));                 //调转带ID         startActivityForResult(i, ACTIVITY_EDIT);     }

    //返回后刷新列表     @Override     protected void onActivityResult(int requestCode, int resultCode,             Intent intent) {         super.onActivityResult(requestCode, resultCode, intent);         renderListView();     } }

编辑页面

import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText;

public class ActivityDiaryEdit extends Activity {

    //初始化成员变量     private EditText mTitleText;     private EditText mBodyText;     private Long mRowId;     private DiaryDbAdapter mDbHelper; // 数据库操作类

    @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         //初始化数据操作控件         mDbHelper = new DiaryDbAdapter(this);         mDbHelper.open();         //设置页面         setContentView(R.layout.diary_edit);         //获得页面控件         mTitleText = (EditText) findViewById(R.id.title);         mBodyText = (EditText) findViewById(R.id.body);         Button confirmButton = (Button) findViewById(R.id.confirm);                 mRowId = null;         // 每一个intent都会带一个Bundle型的extras数据。         Bundle extras = getIntent().getExtras();                 //说明是编辑         if (extras != null) {             //获得传递过来的参数             String title = extras.getString(DiaryDbAdapter.KEY_TITLE);             String body = extras.getString(DiaryDbAdapter.KEY_BODY);             mRowId = extras.getLong(DiaryDbAdapter.KEY_ROWID);

            //初始化控件             if (title != null) {                 mTitleText.setText(title);             }             if (body != null) {                 mBodyText.setText(body);             }         }

        //设置保存事件         confirmButton.setOnClickListener(new View.OnClickListener() {             public void onClick(View view) {                 String title = mTitleText.getText().toString();                 String body = mBodyText.getText().toString();                 //不等于空是修改，否则添加                 if (mRowId != null) {                     mDbHelper.updateDiary(mRowId, title, body);                 } else                     mDbHelper.createDiary(title, body);                                 Intent mIntent = new Intent();                 setResult(RESULT_OK, mIntent);//设置点击按键                 finish();//结束页面             }

        });     } }