在ActionBar裡面加入搜尋框是現在APP應用的常用做法。要想把搜尋做好,可不是那麼容易。涉及到自動提示和真正的搜尋。下圖是我對一個相對完整的搜尋框涉及的元素關系做了一個圖,箭頭隻表示它們之間有關系,不是類圖中的繼承。
一個Activity會有一個ActionBar,預設情況下。你可以在ActionBar裡面添加菜單條目。菜單條目可以設定标題,圖示以及關聯的ActionView,這裡我們關聯了一個SearchView。SearchView和SearchableInfo關聯,和搜尋服務關聯。同時為了更好的處理關于SearchView的事件響應,我們抽象了一個控制類MovieSearch。它是邏輯控制中心,有搜尋完了的跳轉SearchActivity(包含SearchFregment),也有内容提示。内容提示主要是根據輸入的字進行聯想,或者根據曆史記錄或者熱門搜尋。是以這裡有個SearchHistory,它又和資料表相關。
在加載自動提示的地方,我們用到了一個類MatrixCursor,是以,我們詳細的了解這個類的用法。
假如有一個如下的資料庫表結構
_id
name
price
R.drawable.ic_launcher
zhangsan
39
lisi
40
wangwu
41
zhaoliu
42
現在咱們就通過MatrixCursor這個東西,來虛構出一張上面那樣的表結構,下面通過一個例子,就可以完全了解MatrixCursor這個東西
見示例代碼如下:
<span style="font-size:14px;">package com.test.matrixcursor;
import android.app.ListActivity;
import android.database.MatrixCursor;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.View;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends ListActivity {
private static final String[] COLUMN_NAME = { "_id", "name", "price" };
private MatrixCursor matrixCursor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
createList();
//createList2();
}
private void createList() {
matrixCursor = new MatrixCursor(COLUMN_NAME, 1);
startManagingCursor(matrixCursor);
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "zhangsan",
39 });
matrixCursor
.addRow(new Object[] { R.drawable.ic_launcher, "lisi", 40 });
.addRow(new Object[] { R.drawable.ic_launcher, "wangwu", 41 });
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "zhaoliu",
42 });
.addRow(new Object[] { R.drawable.ic_launcher, "sunqi", 43 });
setListAdapter(new SimpleCursorAdapter(this, R.layout.activity_main,
matrixCursor, COLUMN_NAME, new int[] { R.id.icon, R.id.name,
R.id.price }));
private void createList2() {
MatrixCursor.RowBuilder builder1 = matrixCursor.newRow();
builder1.add(R.drawable.ic_launcher);
builder1.add("zhangsan");
builder1.add(39);
MatrixCursor.RowBuilder builder2 = matrixCursor.newRow();
builder2.add(R.drawable.ic_launcher);
builder2.add("lisi");
builder2.add(40);
MatrixCursor.RowBuilder builder3 = matrixCursor.newRow();
builder3.add(R.drawable.ic_launcher);
builder3.add("wangwu");
builder3.add(41);
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
matrixCursor.moveToPosition(position);
StringBuilder builder = new StringBuilder();
builder.append("Name:")
.append(matrixCursor.getString(matrixCursor
.getColumnIndex("name"))).append("\n");
builder.append("Price:")
.getColumnIndex("price"))).append("\n");
Toast.makeText(getApplicationContext(), builder.toString(), 1000)
.show();
}
</span>
實作步驟僅需3步,下面通過字元數組來說明:
步驟1.首先建立一個字元數組,且字元數組的值對應着表的字段,如下:
String[] COLUMN_NAME = { "_id", "name", "price" };
步驟2.利用MatrixCursor的構造方法,構造一個MatrixCursor,傳入的參數即是步驟1中建立的字段數組,如下:
MatrixCursormatrixCursor=newMatrixCursor(COLUMN_NAME);
也可以指定初始大小,如:
matrixCursor=newMatrixCursor( COLUMN_NAME,
10);
步驟3. 通過matrixCursor 的addRow方法添加一行值,相當于向資料庫中插入一條記錄,如下:
matrixCursor.addRow(new Object[] { R.drawable.ic_launcher, "zhangsan",39 });
注:步驟3也可以通過構造一個MatrixCursor.RowBuilder來實作,也是相當于向資料庫中插入一條記錄,如下:
MatrixCursor.RowBuilder builder1 = matrixCursor.newRow();
builder1.add(R.drawable.ic_launcher);
builder1.add("zhangsan");
builder1.add(39);
//builder1.add(399999);
通過上面三步即可完成MatrixCursor 的構造。從MatrixCursor 中取出資料的過程與Cursor相同,不再贅述!
注釋:如果builder1對象add的數量大于字段的個數,即打開builder1.add(399999);注釋,那麼将會報以下錯誤:
02-27 19:00:44.882: W/dalvikvm(29036): threadid=1: thread exiting with uncaught exception (group=0x41e689a8)
02-27 19:00:44.882: W/dalvikvm(29036): threadid=1: uncaught exception occurred
02-27 19:00:44.883: W/System.err(29036): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.matrixcursor/com.test.matrixcursor.MainActivity}:android.database.CursorIndexOutOfBoundsException: No more
columns left.
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2356)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2408)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread.access$600(ActivityThread.java:167)
02-27 19:00:44.883: W/System.err(29036): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1378)
02-27 19:00:44.883: W/System.err(29036): at android.os.Handler.dispatchMessage(Handler.java:107)
02-27 19:00:44.883: W/System.err(29036): at android.os.Looper.loop(Looper.java:194)
02-27 19:00:44.884: W/System.err(29036): at android.app.ActivityThread.main(ActivityThread.java:5405)
02-27 19:00:44.884: W/System.err(29036): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 19:00:44.884: W/System.err(29036): at java.lang.reflect.Method.invoke(Method.java:525)
02-27 19:00:44.884: W/System.err(29036): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:838)
02-27 19:00:44.884: W/System.err(29036): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
02-27 19:00:44.884: W/System.err(29036): at dalvik.system.NativeStart.main(Native Method)
02-27 19:00:44.886: W/System.err(29036): Caused by: android.database.CursorIndexOutOfBoundsException: No more columns left.
02-27 19:00:44.887: W/System.err(29036): at android.database.MatrixCursor$RowBuilder.add(MatrixCursor.java:206)
02-27 19:00:44.887: W/System.err(29036): at com.test.matrixcursor.MainActivity.createList(MainActivity.java:46)
02-27 19:00:44.888: W/System.err(29036): at com.test.matrixcursor.MainActivity.onCreate(MainActivity.java:20)
02-27 19:00:44.889: W/System.err(29036): at android.app.Activity.performCreate(Activity.java:5127)
02-27 19:00:44.889: W/System.err(29036): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1151)
02-27 19:00:44.890: W/System.err(29036): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2320)
程式運作結果: