自訂 Android Preference——SpinnerPreference的私人定製

標籤：android   preference   spinner   widget   布局   

因客戶需求SpinnerPreference，網上各種搜尋不到，無奈只能重寫組件，現將過程分享大家。

自訂SpinnerPreference一：首先從擴充preference開始：類檔案必須繼承自Preference並實現建構函式，如下

public MySpinnerPreference(Context context) {        super(context);    }    public MySpinnerPreference(Context context, AttributeSet attrs) {        super(context, attrs);    }    public MySpinnerPreference(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);    }

二：自訂布局檔案的重寫

<?xml version="1.0" encoding="utf-8"?><!-- Layout of a header item in PreferenceActivity. --><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:background="?android:attr/activatedBackgroundIndicator"    android:gravity="center_vertical"    android:minHeight="48dp"    android:paddingEnd="?android:attr/scrollbarSize"    android:paddingStart="@dimen/mypreference_margin_start" >    <RelativeLayout        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_marginBottom="6dip"        android:layout_marginEnd="6dip"        android:layout_marginStart="2dip"        android:layout_marginTop="6dip"        android:layout_weight="1"        android:gravity="center_vertical" >        <TextView            android:id="@+android:id/title"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:ellipsize="marquee"            android:fadingEdge="horizontal"            android:singleLine="true"            android:textAppearance="?android:attr/textAppearanceMedium" />        <TextView            android:id="@+android:id/summary"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_alignStart="@android:id/title"            android:layout_below="@android:id/title"            android:ellipsize="end"            android:maxLines="2"            android:textAppearance="?android:attr/textAppearanceSmall" />    </RelativeLayout>    <!-- Preference should place its actual preference widget here. -->    <Spinner        android:id="@+id/spinner1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:padding="8dip" /></LinearLayout>

三：引用一個layout檔案為其指定UI，可以通過實現如下兩個回呼函數：

  @Override    protected View onCreateView(ViewGroup parent) {        // TODO Auto-generated method stub        return super.onCreateView(parent);    }    @Override    protected void onBindView(View view) {        super.onBindView(view);        mSpinner = (Spinner) view.findViewById(R.id.spinner1);        String[] arraystr = view.getResources().getStringArray(R.array.itemspinner_values);        mAdapter = new ArrayAdapter<String>(view.getContext(), android.R.layout.simple_spinner_dropdown_item, arraystr);        //  也可一自己定義適配器的樣式        // mAdapter = new ArrayAdapter<String>(view.getContext(), R.layout.preference_categoary, mMeausStr);        mSpinner.setAdapter(mAdapter);        mSpinner.setOnItemSelectedListener(this);    }

四：為組建添加需要的事件這裡 implements OnItemSelectedListener

    @Override    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {        if (callChangeListener(position)) {            setValue(position);        }    }    @Override    public void onNothingSelected(AdapterView<?> parent) {    }

五：儲存或持久化我們的改動

設置我們的改動

public void setValue(int value) {        // Always persist/notify the first time.        final boolean changed = !TextUtils.equals(Integer.toString(mValue), Integer.toString(value));        if (changed || !mValueSet) {            mValue = value;            mValueSet = true;            persistInt(value);            if (changed) {                notifyChanged();            }        }    }   @Override    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {        mPos = position;        if (callChangeListener(position)) {            setValue(position);        }    }

可以持久化多種基礎資料型別 (Elementary Data Type)

    @Override    protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {        setValue(restoreValue ? getPersistedInt(mValue) : (Integer) defaultValue);    }

六效果圖