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8.2 Android Basic 数据存储 Database SQLite Demo 2

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<<SQLiteDemo2.zip>>

SQLite Demo 2

本演練演示一個日記本程序

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新建項目SQLiteDemo2, 編輯res/layout/main.xml 文件
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<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk

/res/android"

android:layout_width="wrap_content" android:layout_height="wrap_content">

<ListView android:id="@+id/android:list" android:layout_width="wrap_content"

android:layout_height="wrap_content" />

<TextView android:id="@+id/android:empty"

android:layout_width="wrap_content" android:layout_height="wrap_content"

android:text="沒有日記內容點擊菜單開始寫日記" />

</LinearLayout>

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2. 在res/layout/ 新建布局文件 diary_row.xml 用于顯示日記的界面：

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout android:id="@+id/row"

xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent">

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<TextView android:id="@+id/text1"

android:layout_width="wrap_content" android:layout_height="30px"

android:maxWidth="200dip"

android:textSize="22sp"

android:layout_marginTop="10dip"

android:text="標題" />

<TextView android:id="@+id/created" android:layout_width="wrap_content"

android:layout_height="35px" android:layout_alignParentRight="true"

android:layout_marginLeft="10dip"

android:layout_marginTop="10dip"

android:text="xxxx年xx月xx日" />

</RelativeLayout>

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3. 在res/layout/新建布局文件 diary_edit.xml 用于編輯日記的界面

<?xml version="1.0" encoding="utf-8"?>

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical" android:layout_width="fill_parent"

android:layout_height="fill_parent">

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<LinearLayout android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="wrap_content">

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<TextView android:layout_width="wrap_content"

android:layout_height="wrap_content" android:text="@string/title"

android:padding="2px" />

<EditText android:id="@+id/title"

android:layout_width="fill_parent"

android:layout_height="wrap_content" android:layout_weight="1" />

</LinearLayout>

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<TextView android:layout_width="wrap_content"

android:layout_height="wrap_content" android:text="@string/body" />

<EditText android:id="@+id/body" android:layout_width="fill_parent"

android:layout_height="fill_parent" android:layout_weight="1"

android:scrollbars="vertical" android:gravity="top" />

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<Button android:id="@+id/confirm" android:text="@string/confirm"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

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</LinearLayout>

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4. 打開res/values/string.xml，添加如下內容：

<?xml version="1.0" encoding="utf-8"?>

<resources>

<string name="hello">Hello World, SQLiteDemo2!</string>

<string name="app_name">SQLiteDemo2</string>

<string name="menu_insert">添加一篇新日記</string>

<string name="menu_delete">刪除一篇日記</string>

<string name="title">標題</string>

<string name="body">內容</string>

<string name="confirm">確定</string>

<string name="edit_diary">編輯日記</string>

</resources>

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5. 新建DiaryDbAdapter類，用于封裝對數據庫的操作。

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;

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public class DiaryDbAdapter {

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";

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private static final String TAG = "DiaryDbAdapter";

private DatabaseHelper mDbHelper;

private SQLiteDatabase mDb;

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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);";

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private static final String DATABASE_NAME = "database";

private static final String DATABASE_TABLE = "diary";

private static final int DATABASE_VERSION = 1;

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private final Context mCtx;

private static class DatabaseHelper extends SQLiteOpenHelper {

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DatabaseHelper(Context context) {

super(context, DATABASE_NAME, null, DATABASE_VERSION);

}

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@Override

public void onCreate(SQLiteDatabase db) {

db.execSQL(DATABASE_CREATE);

}

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@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

db.execSQL("DROP TABLE IF EXISTS diary");

onCreate(db);

}

}

public DiaryDbAdapter(Context ctx) {

this.mCtx = ctx;

}

public DiaryDbAdapter open() throws SQLException {

mDbHelper = new DatabaseHelper(mCtx);

mDb = mDbHelper.getWritableDatabase();

return this;

}

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public void closeclose() {

mDbHelper.close();

}

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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) + "時"

+ calendar.get(Calendar.MINUTE) + "分";

initialValues.put(KEY_CREATED, created);

return mDb.insert(DATABASE_TABLE, null, initialValues);

}

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public boolean deleteDiary(long rowId) {

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

}

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public Cursor getAllNotes() {

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return mDb.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_TITLE,

KEY_BODY, KEY_CREATED }, null, null, null, null, null);

}

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public Cursor getDiary(long rowId) throws SQLException {

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Cursor mCursor =

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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;

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}

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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) + "時"

+ calendar.get(Calendar.MINUTE) + "分";

args.put(KEY_CREATED, created);

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

}

}

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6. 新建類DiaryEditActivity類繼承自Activity類用于編輯日記:

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

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public class DiaryEditActivity extends Activity {

private EditText mTitleText;

private EditText mBodyText;

private Long mRowId;

private DiaryDbAdapter mDbHelper;

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@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

mDbHelper = new DiaryDbAdapter(this);

mDbHelper.open();

setContentView(R.layout.diary_edit);

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mTitleText = (EditText) findViewById(R.id.title);

mBodyText = (EditText) findViewById(R.id.body);

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Button confirmButton = (Button) findViewById(R.id.confirm);

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mRowId = null;

// 每一個intent都會帶一個Bundle型的extras數據。

Bundle extras = getIntent().getExtras();

if (extras != null) {

String title = extras.getString(DiaryDbAdapter.KEY_TITLE);

String body = extras.getString(DiaryDbAdapter.KEY_BODY);

mRowId = extras.getLong(DiaryDbAdapter.KEY_ROWID);

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if (title != null) {

mTitleText.setText(title);

}

if (body != null) {

mBodyText.setText(body);

}

}

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confirmButton.setOnClickListener(new View.OnClickListener() {

public void onClick(View view) {

String title = mTitleText.getText().toString();

String body = mBodyText.getText().toString();

if (mRowId != null) {

mDbHelper.updateDiary(mRowId, title, body);

} else

mDbHelper.createDiary(title, body);

Intent mIntent = new Intent();

setResult(RESULT_OK, mIntent);

finish();

}

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});

}

}

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7. 編輯SQLiteDemo2類

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import android.app.Activity;

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;

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public class SQLiteDemo2 extends ListActivity {

private static final int ACTIVITY_CREATE = 0;

private static final int ACTIVITY_EDIT = 1;

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private static final int INSERT_ID = Menu.FIRST;

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

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private DiaryDbAdapter mDbHelper;

private Cursor mDiaryCursor;

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@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

mDbHelper = new DiaryDbAdapter(this);

mDbHelper.open();

renderListView();

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}

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private void renderListView() {

mDiaryCursor = mDbHelper.getAllNotes();

startManagingCursor(mDiaryCursor);

String[] from = new String[] { DiaryDbAdapter.KEY_TITLE,

DiaryDbAdapter.KEY_CREATED };

int[] to = new int[] { R.id.text1, R.id.created };

SimpleCursorAdapter notes = new SimpleCursorAdapter(this,

R.layout.diary_row, mDiaryCursor, from, to);

setListAdapter(notes);

}

@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;

}

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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);

}

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private void createDiary() {

Intent i = new Intent(this, DiaryEditActivity.class);

startActivityForResult(i, ACTIVITY_CREATE);

}

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protected void onListItemClick(ListView l, View v, int position, long id) {

super.onListItemClick(l, v, position, id);

Cursor c = mDiaryCursor;

c.moveToPosition(position);

Intent i = new Intent(this, DiaryEditActivity.class);

i.putExtra(DiaryDbAdapter.KEY_ROWID, id);

i.putExtra(DiaryDbAdapter.KEY_TITLE, c.getString(c

.getColumnIndexOrThrow(DiaryDbAdapter.KEY_TITLE)));

i.putExtra(DiaryDbAdapter.KEY_BODY, c.getString(c

.getColumnIndexOrThrow(DiaryDbAdapter.KEY_BODY)));

startActivityForResult(i, ACTIVITY_EDIT);

}

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@Override

protected void onActivityResult(int requestCode, int resultCode,

Intent intent) {

super.onActivityResult(requestCode, resultCode, intent);

renderListView();

}

}

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8. 在AndroidManifest.xml 中配置

<activity android:name="DiaryEditActivity"></activity>

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轉載于:https://www.cnblogs.com/xingquan/archive/2011/03/25/1995718.html

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