由于系统自带的Preference只支持CheckBoxPreference ListPreference editPreference等几种偏好选项,假如我们需要在Preference中添加SeekBar来实现一个音量控制条的功能,这时候就需要自定义一个类.

这里我们通过继承DialogPreference来实现.

首先定义一个xml布局文件来描述seekbar的布局

seek.xml:

<?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" ><RelativeLayoutandroid:layout_width="wrap_content"android:layout_height="wrap_content" ><TextViewandroid:id="@+id/text1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_alignParentLeft="true"android:text="111" /><TextViewandroid:id="@+id/text2"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_alignParentRight="true"android:text="222" /></RelativeLayout><SeekBarandroid:id="@+id/seekbar1"android:layout_width="match_parent"android:layout_height="wrap_content" /><TextViewandroid:id="@+id/text3"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="333" /></LinearLayout>

接着我们需要定义2个seekbar的属性,minValue和maxValue来分别描述进度条的最小值和最大值.

我们知道自定义控件的属性需要在attrs.xml中声明:

<?xml version="1.0" encoding="utf-8"?>
<resources><declare-styleable name="com.example.dialogpreferencesseekbar.SeekBarPreferences"><attr name="minValue" format="integer" /><attr name="maxValue" format="integer" /></declare-styleable>
</resources>

再来看看我们自定义SeekBarPreference继承于DialogPreference的类SeekBarPreferences.java：

package com.example.dialogpreferencesseekbar;import android.content.Context;
import android.content.res.TypedArray;
import android.preference.DialogPreference;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;public class SeekBarPreferences extends DialogPreference implementsOnSeekBarChangeListener {private static final String PREFERENCE_NS = "http://schemas.android.com/apk/res/com.example.dialogpreferencesseekbar";private static final String ANDROID_NS = "http://schemas.android.com/apk/res/android";private static final String ATTR_DEFAULT_VALUE = "defaultValue";private static final String ATTR_MIN_VALUE = "minValue";private static final String ATTR_MAX_VALUE = "maxValue";private int mMinValue;private int mMaxValue;private int mDefaultValue;private int mCurrentValue;private SeekBar mSeekBar;private TextView mValueText;public SeekBarPreferences(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stubmMinValue = attrs.getAttributeIntValue(PREFERENCE_NS, ATTR_MIN_VALUE, 0);mMaxValue = attrs.getAttributeIntValue(PREFERENCE_NS, ATTR_MAX_VALUE,100);
/********也可以通过Context的obtainStyledAttributes获得自定义的属性值***********/
//		TypedArray array = context.obtainStyledAttributes(attrs,
//				R.styleable.com_example_dialogpreferencesseekbar_SeekBarPreferences);
//		mMaxValue = array.getInteger(R.styleable.com_example_dialogpreferencesseekbar_SeekBarPreferences_maxValue, 100);
//		mMinValue = array.getInteger(R.styleable.com_example_dialogpreferencesseekbar_SeekBarPreferences_minValue, 0);mDefaultValue = attrs.getAttributeIntValue(ANDROID_NS,ATTR_DEFAULT_VALUE, 50);//		array.recycle();}@Overrideprotected View onCreateDialogView() {// TODO Auto-generated method stub// Get current value from settingsmCurrentValue = getPersistedInt(mDefaultValue);// Inflate layoutLayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);View view = inflater.inflate(R.layout.seek, null);// Put minimum and maximum((TextView) view.findViewById(R.id.text1)).setText(Integer.toString(mMinValue));((TextView) view.findViewById(R.id.text2)).setText(Integer.toString(mMaxValue));// Setup SeekBarmSeekBar = (SeekBar) view.findViewById(R.id.seekbar1);mSeekBar.setMax(mMaxValue - mMinValue);mSeekBar.setProgress(mCurrentValue - mMinValue);mSeekBar.setOnSeekBarChangeListener(this);// Put current valuemValueText = (TextView) view.findViewById(R.id.text3);mValueText.setText(Integer.toString(mCurrentValue));return view;}@Overridepublic void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {// TODO Auto-generated method stubmCurrentValue = progress + mMinValue;mValueText.setText(Integer.toString(mCurrentValue));}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}}

这里包含SeekBar的DialogPreference就自定义好了

这时我们需要定义整个Preference的布局文件了dialog_slider.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"xmlns:example="http://schemas.android.com/apk/res/com.example.dialogpreferencesseekbar" ><PreferenceCategory android:title="第一层" ><com.example.dialogpreferencesseekbar.SeekBarPreferencesandroid:defaultValue="25"android:dialogTitle="音量进度条"android:key="seekBarPreference"android:persistent="true"android:summary="touch it"android:title="音量调节"example:maxValue="100"example:minValue="0" /></PreferenceCategory><PreferenceCategory android:title="第二层" ><CheckBoxPreferenceandroid:key="checkbox_preference"android:summary="this is demo"android:title="勾选" /></PreferenceCategory></PreferenceScreen>

包含了两层 第一层是我们上边自定义的呼出SeekBar的偏好选项 下边一层是一个CheckBoxPreference

我们PreferenceFragment将dialog_slider.xml包含进去.

MyDialogFragment.java:

package com.example.dialogpreferencesseekbar;import android.os.Bundle;
import android.preference.PreferenceFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;public class MyDialogFragment extends PreferenceFragment {@Overridepublic void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);addPreferencesFromResource(R.layout.dialog_slider);}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {// TODO Auto-generated method stubreturn super.onCreateView(inflater, container, savedInstanceState);}}

通过FragmentTransaction的replace方法就可以打开我们的自定义的偏好设置了.

效果图: