>>>實現功能
主要是對對SQLite編輯和修改
分析代碼結構，需要NotePadList類用於展示筆記，NotePadAdd類用於實現筆記的添加，需要NotePadDetil實現修改筆記，需要NotePadProvieder實現對數據庫操作。
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第一步，編寫NotePadList
xml部分
<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=".NotePadList" >
<ListView
android:id="@+id/id_listview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>java部分
public class NotePadList extends Activity {
private NotePadProvider nProvider = new NotePadProvider(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setNoteListView();
}
SimpleCursorAdapter adapter;
private void setNoteListView() {
c = qurydata();
//lsitviw
ListView lsv = (ListView) findViewById(R.id.id_listview);
//simpleadapter
adapter=new SimpleCursorAdapter(this,
R.layout.notepadlist,
c, new String[]{"content","created"},
new int[]{R.id.lsit_textview,R.id.lsit_textview2},
CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
lsv.setAdapter(adapter);
lsv.setOnItemClickListener(new OnItemClickListener() { //長按實現頁面跳轉，到notepaddetil
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
c.moveToPosition(position);//獲取點擊位置的Cursor
String content = c.getString(c.getColumnIndex("content"));//查詢取值
Intent intent = new Intent(NotePadList.this, NotepadDetil.class);
intent.putExtra("contentKey",content);//通過intent傳遞相應的值
intent.putExtra("idKey",String.valueOf(position+1));
startActivityForResult(intent, 100);//傳遞請求碼以便執行刷新
}
});
}
Cursor c;/**查詢*/
private Cursor qurydata() {
String sql="select * from notetab";
c =nProvider.query(sql, null);
return c;
}
@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;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {//點擊添加按鈕菜單，跳轉添加界面
if (item.getItemId() == R.id.noteAddId) {
startActivityForResult(new Intent(this, NotePadAdd.class),
100);//請求碼
}
return super.onOptionsItemSelected(item);
}
/**刷新*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode==100&&resultCode==200) {
c = qurydata();<span style="font-family: Arial, Helvetica, sans-serif;">//再次獲取</span>
adapter.changeCursor(c);
}
}
}<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:id="@+id/noteAddId"
android:orderInCategory="100"
android:showAsAction="always"
android:title="添加"
android:icon="@android:drawable/ic_menu_add"/>
</menu>第二步，書寫notePadProvider類，實現對數據庫的操作
java代碼
public class NotePadProvider {
private DBHelper dbHelper;
public NotePadProvider(Context context) {
dbHelper=new DBHelper(context,
"notepad.db", null, 1);
}
/**寫入數據*/
public long insert(String table,ContentValues values){
SQLiteDatabase sdb=dbHelper.getWritableDatabase();//獲取數據庫的寫入功能
long id=sdb.insert(table, null, values);
sdb.close();
return id;
}
/**更新*/
public long updata(String table, ContentValues values, String whereClause, String[] whereArgs){
SQLiteDatabase sdb = dbHelper.getWritableDatabase();
long id = sdb.update(table, values, whereClause, whereArgs);
return id;
}
/**查詢*/
public Cursor query(String sql,String whereArgs[]){
SQLiteDatabase sdb=
dbHelper.getReadableDatabase();<span style="font-family: Arial, Helvetica, sans-serif;">//獲取數據庫的讀入功能</span>
return sdb.rawQuery(sql, whereArgs);
}
/**操作SQLite的一個工具類*/
class DBHelper extends SQLiteOpenHelper{
public DBHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
}
/**數據庫創建時執行，且只執行一次*/
@Override
public void onCreate(SQLiteDatabase db) {
String sql=
"create table if not exists notetab(" +
"_id integer primary key autoincrement," +
"content text not null," +
"created text not null)";
db.execSQL(sql);
Log.i("TAG", "table create ok!");
}
/**數據庫版本升級時執行*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.i("TAG", "onUpgrade");
}
}
}-------------------------------------------------------------------
第三步：編寫NotePadAdd類，實現增加筆記功能
public class NotePadAdd extends Activity {
private EditText et;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note_pad);
et = (EditText) findViewById(R.id.editText1);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.note_pad, menu);
return true;
}
@SuppressLint("SimpleDateFormat")
@Override
public boolean onOptionsItemSelected(MenuItem item) {
NotePadProvider nProvider = new NotePadProvider(this);
if (item.getItemId() == R.id.save) {
//獲得頁面數據
String content = et.getText().toString();
//對數據進行非空驗證
if (TextUtils.isEmpty(content)) {
et.setError("null");
return true;
}
//將數據寫到數據庫
ContentValues values = new ContentValues();
values.put("content", content);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
values.put("created", sdf.format(new Date()));
long id = nProvider.insert("notetab", values);
if (id==-1) {
Toast.makeText(this, "insert error", 0).show();
return true;
}
//關閉當前頁面
setResult(200);//跳轉回notepadlist主界面的時候，自動刷新主界面
finish();
}
return super.onOptionsItemSelected(item);
}
}<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=".NotePadAdd" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView1"
android:layout_below="@+id/textView1"
android:layout_marginLeft="22dp"
android:layout_marginTop="31dp"
android:ems="10"
android:hint="輸入">
<requestFocus />
</EditText>
</RelativeLayout><menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:id="@+id/save"
android:orderInCategory="100"
android:showAsAction="always"
android:title="保存"
android:icon="@android:drawable/ic_menu_save"></item>
</menu>第四步，編寫NotePadDetil,實現修改
java
public class NotepadDetil extends Activity {
private EditText et;
private MenuItem et_save;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_notepad_detil);
initView();
et.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
et.setFocusableInTouchMode(true);
et_save.setVisible(true);
}
});
}
private void initView() {
et = (EditText) findViewById(R.id.id_editText);
Intent intent = getIntent();
String contentNew = intent.getStringExtra("contentKey");
String contentOld = et.getText().toString();
if (TextUtils.isEmpty(contentOld)) {//非空判斷
et.setText(contentNew);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.notepad_detil, menu);
et_save = menu.findItem(R.id.edt_save);
et_save.setVisible(false);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.edt_save) {
//獲取當前頁面的數據
String newcontent = et.getText().toString();
NotePadProvider nProvider=new NotePadProvider(this);
ContentValues values=new ContentValues();
values.put("content", newcontent);
Intent intent=getIntent();
String id=intent.getStringExtra("idKey");
nProvider.updata("notetab",
values, "_id=?", new String[]{id});
//4.關閉頁面
setResult(200);//跳轉後刷新
finish();
}
return super.onOptionsItemSelected(item);
}
}<menu xmlns:android="http://schemas.android.com/apk/res/android" >
<item
android:id="@+id/edt_save"
android:orderInCategory="100"
android:showAsAction="always"
android:title="保存"
android:icon="@android:drawable/ic_menu_save"/>
</menu>
<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=".NotepadDetil" >
<EditText
android:layout_width="wrap_content"
android:id="@+id/id_editText"
android:layout_height="wrap_content"
android:focusable="false"
android:background="@null"/>
</RelativeLayout>