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Filter
翻譯時(shí)間：2010-11-07
版本：Android 2.2 r1
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結(jié)構(gòu)
繼承關(guān)系
public abstract class Filter extends Object
????????
java.lang.Object
???? android.widget.Filter
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類概述
過濾器通過過濾模式來約束數(shù)據(jù)，通常由實(shí)現(xiàn)了Filterable接口的子類來生成。
過濾操作是通過調(diào)用 filter(CharSequence) 或者 filter(CharSequence, android.widget.Filter.FilterListener)這些異步方法來完成的。以上方法一旦被調(diào)用，過濾請求就會被遞交到請求隊(duì)列中等待處理，同時(shí)該操作會取消那些之前遞交的但是還沒有被處理的請求。
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構(gòu)造函數(shù)
???????? public Filter ()
創(chuàng)建一個(gè)新的異步過濾器。
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公共方法
public CharSequence convertResultToString (Object resultValue)
??? 將受過濾的集合對象轉(zhuǎn)換成CharSequence文本。所有繼承了Filter的子類應(yīng)該重寫該方法。該方法的默認(rèn)實(shí)現(xiàn)：如果參數(shù)為null則返回空字符串或者返回參數(shù)的字符串形式.
參數(shù)
??????????????????????????? resultValue? 轉(zhuǎn)換成CharSequence文本的對象
?????????????????? 返回值
??????????????????????????? CharSequence 文本
??????????????????
public final void filter(CharSequence constraint, Filter.FilterListener listener)
啟動一個(gè)異步的過濾操作。對該方法的調(diào)用會取消之前隊(duì)列中等待處理的過濾請求并且遞交新的過濾請求等待執(zhí)行。完成過濾操作之后，通知監(jiān)聽器。
參數(shù)
??????????????????????????? constraint? 過濾數(shù)據(jù)的約束條件
listener? 監(jiān)聽過濾操作完成之后發(fā)出的通知
參見
??????????????????????????? filter(CharSequence)
performFiltering(CharSequence)
publishResults(CharSequence, android.widget.Filter.FilterResults)
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public final void filter(CharSequence constraint)
啟動一個(gè)異步的過濾操作。對該方法的調(diào)用會取消之前隊(duì)列中等待處理的過濾請求并且遞交新的過濾請求等待執(zhí)行。
參數(shù)
??????????????????????????? constraint? 過濾數(shù)據(jù)的約束條件
?????????????????? 參見
??????????????????????????? filter(CharSequence, android.widget.Filter.FilterListener)
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受保護(hù)方法
protected abstract Filter.FilterResults performFiltering (CharSequence constraint)
根據(jù)約束條件調(diào)用一個(gè)工作線程過濾數(shù)據(jù)。子類必須實(shí)現(xiàn)該方法來執(zhí)行過濾操作。過濾結(jié)果以Filter.FilterResults的形式返回，然后在UI線程中通過publishResults(CharSequence,android.widget.Filter.FilterResults)方法來發(fā)布。
約定：當(dāng)約束條件為null時(shí)，原始數(shù)據(jù)必須被恢復(fù)。
參數(shù)
constraint ????? 約束條件
返回值
過濾結(jié)果
參見
??? ?????????????????? filter(CharSequence, android.widget.Filter.FilterListener)
??? ?????????????????? publishResults(CharSequence, android.widget.Filter.FilterResults)
?? ???????????????????? Filter.FilterResults
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protected abstract void publishResults (CharSequence constraint, Filter.FilterResults results)
通過調(diào)用UI線程在用戶界面發(fā)布過濾結(jié)果。子類必須實(shí)現(xiàn)該方法來顯示performFiltering(CharSequence)的過濾結(jié)果。
參數(shù)
constraint ????? 約束條件
results ?? 過濾結(jié)果
參見
??? ?????????????????? filter(CharSequence, android.widget.Filter.FilterListener)
performFiltering(CharSequence)
Filter.FilterResults
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補(bǔ)充
示例代碼
?????????????????? 未過濾的數(shù)據(jù)如下圖所示：
為過濾器設(shè)置約束條件（只顯示年齡為22的用戶）：
???????? Java：TestFilter.java
public class TestFilter extends ListActivity {
???
??? @Override
??? public void onCreate(Bundle savedInstanceState) {
??????? super.onCreate(savedInstanceState);
??????? setContentView(R.layout.main);
??????? ArrayList<HashMap<String,String>> list = new
????????? ????????????ArrayList <HashMap<String, String>>();
??????? HashMap<String, String> map1 = new HashMap<String, String>();
??????? HashMap<String, String> map2 = new HashMap<String, String>();
??????? HashMap<String, String> map3 = new HashMap<String, String>();
??????? map1.put("name", "henly");
??????? map1.put("age", "22");
??????? map2.put("name", "john");
??????? map2.put("age", "23");
??????? map3.put("name", "lilei");
??????? map3.put("age", "22");
??????? list.add(map1);
??????? list.add(map2);
????? ??list.add(map3);
??????? SimpleAdapter simpleAdapter = new SimpleAdapter(this, list, R.layout.user, new String[]{"name","age"}, new int[]{R.id.name,R.id.age});
??????? String str = new String("22");
??????? CharSequence constraint = str.subSequence(0, str.length());
??????? Filter filter = simpleAdapter.getFilter(); //得到一個(gè)過濾器
??????? filter.filter(constraint);? //為該過濾器設(shè)置約束條件
??????? setListAdapter(simpleAdapter);
??? }
}
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???????? XML：main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
??? android:orientation="vertical"
??? android:layout_width="fill_parent"
??? android:layout_height="fill_parent"
??? >
??? <LinearLayout android:id="@+id/listlinearlayout"
??? ???????? android:layout_width="fill_parent"
??? ???????? android:layout_height="wrap_content"
??? ???????? android:orientation="vertical">
??? ???????? <ListView android:id="@id/android:list"
??? ?????????????????? android:layout_width="fill_parent"
??? ?????????????????? android:layout_height="wrap_content"
??? ?????????????????? android:drawSelectorOnTop="false"
??? ?????????????????? android:scrollbars="vertical" />
??? ???????? </LinearLayout>
</LinearLayout>
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XML：user.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
??? android:orientation="horizontal"
??? android:layout_width="fill_parent"
??? android:layout_height="fill_parent"
??? android:paddingLeft="12dip"
??? android:paddingRight="12dip"
??? android:paddingTop="1dip"
??? android:paddingBottom="1dip"
??? >
<TextView android:id="@+id/name"
???????? android:layout_width="150dip"
???????? android:layout_height="30dip"
???????? android:textSize="12pt"
???????? />
<TextView android:id="@+id/age"
???????? android:layout_width="wrap_content"
???????? android:layout_height="wrap_content"
???????? android:textSize="12pt"
???????? />
</LinearLayout>