NotePad笔记本应用功能拓展，添加时间戳显示和查询功能（根据标题查询）
一、NoteList中显示条目增加时间戳显示
过程及重要代码
要增加时间戳，首先要获取当前时间，北京时间要用GMT时间加八小时得到（这里是创建Note时获取的时间）
Date date = new Date(now);
SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
format.setTimeZone(TimeZone.getTimeZone("GMT+08:00"));
String formatDate = format.format(date);
原程序已经在数据库SQLite定义好了时间变量，所以可以把获取到的时间赋值给时间变量
if (values.containsKey(NotePad.Notes.COLUMN_NAME_CREATE_DATE) == false) {
values.put(NotePad.Notes.COLUMN_NAME_CREATE_DATE, formatDate);
}
if (values.containsKey(NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE) == false) {
values.put(NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE, formatDate);
}
时间戳是显示在每条Note的下面，所以在noteslist_item.xml添加一个用于显示时间戳的TextView
<TextView
android:id="@+id/text1_date"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="17dp"
android:paddingLeft="5dip"
/>
接着在它的java文件NoteList.java中关于显示Note的函数里加上时间的显示
private static final String[] PROJECTION = new String[] {
NotePad.Notes._ID, // 0
NotePad.Notes.COLUMN_NAME_TITLE, // 1
NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE //日期
};
private static final int COLUMN_INDEX_TITLE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setDefaultKeyMode(DEFAULT_KEYS_SHORTCUT);
Intent intent = getIntent();
if (intent.getData() == null) {
intent.setData(NotePad.Notes.CONTENT_URI);
}
getListView().setOnCreateContextMenuListener(this);
Cursor cursor = managedQuery(
getIntent().getData(), // Use the default content URI for the provider.
PROJECTION, // Return the note ID and title for each note.
null, // No where clause, return all records.
null, // No where clause, therefore no where column values.
NotePad.Notes.DEFAULT_SORT_ORDER // Use the default sort order.
);
String[] dataColumns = {
NotePad.Notes.COLUMN_NAME_TITLE,
NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE
} ;
int[] viewIDs = {
android.R.id.text1,
R.id.text1_date
};
SimpleCursorAdapter adapter
= new SimpleCursorAdapter(
this, // The Context for the ListView
R.layout.noteslist_item, // Points to the XML for a list item
cursor, // The cursor to get items from
dataColumns,
viewIDs
);
setListAdapter(adapter);
}
注意，还要在NoteEditor.java里也添加获取时间的功能（这里是编辑Note时获取的时间），不然无法正确显示编辑Note后的时间
效果截图
二、添加笔记查询功能（根据标题查询）
过程及重要代码
先在顶部的菜单栏中添加查找的图标,这里用的是Android Studio自带图标库里的ic_menu_search
代码：
<item
android:id="@+id/menu_search"
android:icon="@android:drawable/ic_menu_search"
android:title="Search"
app:showAsAction="always" />
再新建一个Activity——NoteSearch,用于查找功能的布局和功能实现
布局样式：
代码：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<SearchView
android:id="@+id/search_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:iconifiedByDefault="false"
/>
<ListView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
接着在菜单栏java文件的switch选择中，添加查找功能的case
case R.id.menu_search:
/*
查找功能
*/
Intent intent = new Intent(this, NoteSearch.class);
this.startActivity(intent);
return true;
然后在NoteSearch.java里完成查找功能的实现
原理：在用Cursor获取数据库的数据时，添加SearchView里的查找条件selection
public boolean onQueryTextChange(String string) {
String selection1 = NotePad.Notes.COLUMN_NAME_TITLE+" like ? or "+NotePad.Notes.COLUMN_NAME_NOTE+" like ?";
String[] selection2 = {"%"+string+"%","%"+string+"%"};
Cursor cursor = sqLiteDatabase.query(
NotePad.Notes.TABLE_NAME,
PROJECTION, // The columns to return from the query
selection1, // The columns for the where clause
selection2, // The values for the where clause
null, // don't group the rows
null, // don't filter by row groups
NotePad.Notes.DEFAULT_SORT_ORDER // The sort order
);
剩下的显示功能，用原来NoteList的显示代码即可完成
// The names of the cursor columns to display in the view, initialized to the title column
String[] dataColumns = {
NotePad.Notes.COLUMN_NAME_TITLE,
NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE
} ;
// The view IDs that will display the cursor columns, initialized to the TextView in
// noteslist_item.xml
int[] viewIDs = {
android.R.id.text1,
R.id.text1_date
};
// Creates the backing adapter for the ListView.
SimpleCursorAdapter adapter
= new SimpleCursorAdapter(
this, // The Context for the ListView
R.layout.noteslist_item, // Points to the XML for a list item
cursor, // The cursor to get items from
dataColumns,
viewIDs
);
// Sets the ListView's adapter to be the cursor adapter that was just created.
listView.setAdapter(adapter);
return true;
}
onCreate也基本沿用了原来NoteList.java的实现代码
ListView listView;
SQLiteDatabase sqLiteDatabase;
/**
* The columns needed by the cursor adapter
*/
private static final String[] PROJECTION = new String[]{
NotePad.Notes._ID, // 0
NotePad.Notes.COLUMN_NAME_TITLE, // 1
NotePad.Notes.COLUMN_NAME_MODIFICATION_DATE//时间
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.note_search);
SearchView searchView = findViewById(R.id.search_view);
Intent intent = getIntent();
if (intent.getData() == null) {
intent.setData(NotePad.Notes.CONTENT_URI);
}
listView = findViewById(R.id.list_view);
sqLiteDatabase = new NotePadProvider.DatabaseHelper(this).getReadableDatabase();
searchView.setOnQueryTextListener(this);
}
效果截图
