Deletes all rows from all the tables that are registered to this database as entities().

This does NOT reset the auto-increment value generated by autoGenerate().

After deleting the rows,Room will set a WAL checkpoint and run VACUUM. This means that the data is completely erased. The space will be reclaimed by the system if the amount surpasses the threshold of database file size.

我在我的项目中检查了它,看起来db在该调用之后没有数据,但是当我拉动时
 来自我的设备的* .db文件并在sqlite查看器中打开它我已经看到所有数据都存在,表格已填满且没有任何内容被删除.
怎么可能？我认为这是我的应用程序中的潜在缺陷.请提供清洁室数据库的可靠方法

looks like db has no data after that call

这意味着该方法有效.

when I pulled *.db file from my device and opened it in sqlite viewer
I’ve seen that all the data exists

很可能事务还没有从WAL文件移动到原始数据库.

解

您可以使用wal_checkpoint pragma强制检查点.根据数据库查询以下语句.

pragma wal_checkpoint(full)

/**
 * Create a linear gradient shader to show variations in value.
 */
private void setVerValSlider() {
    float[] hsv = new float[3];
    hsv[0] = mHSV[0];
    hsv[1] = mHSV[1];
    hsv[2] = 1;
    int col = Color.HSVToColor(hsv);

    int colors[] = new int[2];
    colors[0] = col;
    colors[1] = 0xFF000000;
    GradientDrawable gradDraw = new GradientDrawable(Orientation.TOP_BottOM,colors);
    gradDraw.setDither(true);
    gradDraw.setLevel(10000);
    gradDraw.setBounds(0,mSliderThicknessPx,mPaletteDimPx);
    gradDraw.draw(mVerSliderCv);
}

/**
 * Creates a new drawable (implementation of the Drawable object may vary depending on the OS version).
 * The result Drawable will be colored with the given color,and clipped to match the given bounds.
 * Note that the drawable's alpha is set to 0 when argument color is {@link Color#TRANSPARENT}.
 *
 * @param color  Integer color used to color the output drawable
 * @param bounds Four-dimensional vector representing drawable bounds
 * @return Colored and clipped drawable object
 */
@NonNull
public static Drawable createColoredDrawable(@ColorInt final int color,@Nullable final Rect bounds) {
    // create the drawable depending on the OS (pre-Honeycomb Couldn't use color drawables inside state lists)
    Drawable drawable;
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB || bounds != null) {
        drawable = new GradientDrawable(Orientation.BottOM_TOP,new int[] { color,color }).mutate();
    } else {
        drawable = new ColorDrawable(color).mutate();
    }

    // set the alpha value
    if (color == Color.TRANSPARENT) {
        drawable.setAlpha(0);
    }

    // update bounds
    if (bounds != null) {
        drawable.setBounds(bounds);
    }
    return drawable;
}

protected View makeHeaderView(int headerHeight,float headerRadius) {
    LayoutParams headerParams = new LayoutParams(LayoutParams.FILL_PARENT,headerHeight);

    TextView header = new TextView(getContext());

    if(colors != null) {
        GradientDrawable headerBG = new GradientDrawable(Orientation.BottOM_TOP,new int[]{colors.getColor(Colors.AUTH_PANEL_BottOM),colors.getColor(Colors.AUTH_PANEL_TOP)});
        headerBG.setCornerRadii(new float[]{headerRadius,headerRadius,0.0f,0.0f});

        CompatUtils.setBackgroundDrawable(header,headerBG);
    }

    if(localizationService != null) {
        header.setText(localizationService.getString(I18NConstants.SHARE_HEADER));
    }

    header.setTextSize(TypedValue.COMPLEX_UNIT_DIP,18);
    header.setTextColor(Color.WHITE);
    header.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);
    header.setLayoutParams(headerParams);

    return header;
}

@Override
protected ImageView makeImage() {
    defaultProfilePicture = drawables.getDrawable(Socialize.DEFAULT_USER_ICON);
    profilePicture = new ImageView(getContext());

    int imageSize = displayUtils.getDIP(64);
    int imagePadding = displayUtils.getDIP(4);

    LayoutParams imageLayout = new LinearLayout.LayoutParams(imageSize,imageSize);

    GradientDrawable imageBG = new GradientDrawable(Orientation.BottOM_TOP,new int[] {Color.WHITE,Color.WHITE});
    imageBG.setstroke(2,Color.BLACK);
    imageBG.setAlpha(64);

    profilePicture.setLayoutParams(imageLayout);
    profilePicture.setPadding(imagePadding,imagePadding,imagePadding);

    CompatUtils.setBackgroundDrawable(profilePicture,imageBG);

    profilePicture.setScaleType(ScaleType.CENTER_CROP);

    return profilePicture;
}

protected View makeHeaderView(int headerHeight,headerBG);
    }

       if(localizationService != null) {
           header.setText(localizationService.getString(I18NConstants.AUTH_HEADER));
       }

    header.setTextSize(TypedValue.COMPLEX_UNIT_DIP,18);
    header.setTextColor(Color.WHITE);
    header.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);
    header.setLayoutParams(headerParams);

    return header;
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    if (bottomShadow == null) {
        bottomShadow = new GradientDrawable(Orientation.BottOM_TOP,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

public SearchView(Context context,StringBuilder queryText) {
    super(context);

    mContext = context;
    mQueryText = queryText;

    mPaint = new Paint();
    mPaint.setAntiAlias(true);

    final SurfaceHolder holder = getHolder();
    holder.setFormat(PixelFormat.TRANSLUCENT);
    holder.addCallback(mSurfaceCallback);

    final Resources res = context.getResources();

    int mExtremeRadius = 128;

    // Gradient colors.
    final int gradientInnerColor = res.getColor(R.color.search_overlay);
    final int gradientOuterColor = res.getColor(R.color.search_overlay);
    final int[] colors = new int[] {gradientInnerColor,gradientOuterColor};
    mGradientBackground =
            new GradientDrawable(Orientation.TOP_BottOM,colors);
    mGradientBackground.setGradientType(GradientDrawable.LINEAR_GRADIENT);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(
                R.drawable.two_line);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.white);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(
                R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

/**
 * Create a linear gradient shader to show variations in value.
 */
private void setVerValSlider() {
    float[] hsv = new float[3];
    hsv[0] = mHSV[0];
    hsv[1] = mHSV[1];
    hsv[2] = 1;
    int col = Color.HSVToColor(hsv);

    int colors[] = new int[2];
    colors[0] = col;
    colors[1] = 0xFF000000;
    GradientDrawable gradDraw = new GradientDrawable(Orientation.TOP_BottOM,SLIDER_THICKnesS,PALETTE_DIM);
    gradDraw.draw(mVerSliderCv);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

/**
 * Inits the.
 */
private void init() {
    l = new char[] {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z','#' };
    paint = new Paint();
    paint.setColor(Color.parseColor("#949494"));
    paint.setTypeface(Typeface.DEFAULT_BOLD);
    paint.setTextSize(22);
    paint.setAntiAlias(true);
    paint.setTextAlign(Paint.Align.CENTER);

    gradientDrawable = new GradientDrawable(Orientation.BottOM_TOP,new int []{0x99B0B0B0,0x99B0B0B0});
    gradientDrawable.setCornerRadius(30);

}

public ActionBarBackgroundUpdater(Window paramWindow,PlayHeaderListLayout paramPlayHeaderListLayout)
{
  this.mWindow = paramWindow;
  this.mHeaderListLayout = paramPlayHeaderListLayout;
  Resources localResources = paramPlayHeaderListLayout.getResources();
  this.mTransparentBackground = new ColorDrawable(0);
  final int i = FinskySearchToolbar.getToolbarHeight(this.mHeaderListLayout.getContext());
  int[] arrayOfInt = new int[2];
  arrayOfInt[0] = this.mHeaderListLayout.getResources().getColor(2131689730);
  arrayOfInt[1] = 0;
  this.mProtectionBackground = new GradientDrawable(GradientDrawable.Orientation.TOP_BottOM,arrayOfInt)
  {
    protected final void onBoundsChange(Rect paramAnonymousRect)
    {
      if (paramAnonymousRect.bottom - paramAnonymousRect.top > i) {
        paramAnonymousRect.bottom = (paramAnonymousRect.top + i);
      }
      super.onBoundsChange(paramAnonymousRect);
    }
  };
  this.mBaseBackground = this.mProtectionBackground;
  this.mSearchStatusBarColor = localResources.getColor(2131689676);
  this.mWasHeaderListFloating = this.mHeaderListLayout.isHeaderFloating();
  this.mWasstatusBarUnderlayProtectingControls = this.mHeaderListLayout.isstatusBarUnderlayProtectingControls();
  updateActionBar();
}

public void setLastLineOverdrawColor(int paramInt)
{
  if (!this.mToDrawOverLastLineIfNecessary)
  {
    this.mLastLineOverdrawPaint = new Paint();
    this.mLastLineOverdrawPaint.setStyle(Paint.Style.FILL_AND_stroke);
    Resources localResources = getResources();
    this.mLastLineFadeOutSize = localResources.getDimensionPixelSize(R.dimen.play_text_view_fadeout);
    this.mLastLineFadeOutHintMargin = localResources.getDimensionPixelSize(R.dimen.play_text_view_fadeout_hint_margin);
  }
  this.mLastLineOverdrawPaint.setColor(paramInt);
  GradientDrawable.Orientation localOrientation = GradientDrawable.Orientation.LEFT_RIGHT;
  int[] arrayOfInt = new int[2];
  arrayOfInt[0] = (0xFFFFFF & paramInt);
  arrayOfInt[1] = paramInt;
  this.mLastLineFadeOutDrawable = new GradientDrawable(localOrientation,arrayOfInt);
  this.mToDrawOverLastLineIfNecessary = true;
}

public final void a(View paramView,Bundle paramBundle)
{
  super.a(paramView,paramBundle);
  this.ad = ((MediaView)paramView.findViewById(dl.ae));
  this.ae = ((ImageButton)paramView.findViewById(dl.N));
  this.af = ((ProgressBar)paramView.findViewById(dl.ag));
  this.ad.c(aaw.qd);
  this.ad.d(aaw.qd);
  this.ad.n = true;
  int[] arrayOfInt = new int[3];
  arrayOfInt[0] = g().getColor(aaw.qc);
  arrayOfInt[1] = g().getColor(aaw.qe);
  arrayOfInt[2] = g().getColor(aaw.qc);
  GradientDrawable localGradientDrawable = new GradientDrawable(GradientDrawable.Orientation.BottOM_TOP,arrayOfInt);
  localGradientDrawable.setGradientType(0);
  this.ad.b(localGradientDrawable);
  this.ae.setonClickListener(this);
  w();
  if (paramBundle != null) {
    this.ad.a((ipf)paramBundle.getParcelable("current_media_ref"));
  }
}

protected void init(Context context,AttributeSet attrs) {
    Resources res = getResources();
    this.setCenterDrawable(res.getDrawable(R.drawable.wheel_val_light));
    this.setBackgroundResource(R.drawable.wheel_bg_light);

    GradientDrawable topShadow = new GradientDrawable(Orientation.TOP_BottOM,new int[] { 0x00000000,0x00000000 });
    this.setTopShadowDrawable(topShadow);

    GradientDrawable bottomShadow = new GradientDrawable(Orientation.BottOM_TOP,0x00000000 });
    this.setBottomShadowDrawable(bottomShadow);

    mTextColorValue = 0xFF000000;
    mTextColorItems = 0xFF888888;

    TEXT_SIZE = (int) AppUtil.sp2px(getContext(),18);
    setFakeBoldText(false);
    setCyclic(true);
}

public SearchView(Context context,StringBuilder queryText,Searchtextformatter
        textformatter) {
    super(context);

    mQueryText = queryText;
    mtextformatter = textformatter;

    final SurfaceHolder holder = getHolder();
    holder.setFormat(PixelFormat.TRANSLUCENT);
    holder.addCallback(mSurfaceCallback);

    // Gradient colors.
    final int[] colors = new int[] {GRADIENT_INNER_COLOR,GRADIENT_OUTER_COLOR};
    mGradientBackground = new GradientDrawable(Orientation.TOP_BottOM,colors);
    mGradientBackground.setGradientType(GradientDrawable.LINEAR_GRADIENT);
}

/**
     * Initialize.
     * 
     * @param context
     */
    private void initialize(Context context) {
        this.setVerticalScrollBarEnabled(false);
        this.setSlotInCenter(true);
        this.setorientation(VERTICAL);
        this.setGravity(Gravity.CENTER_HORIZONTAL);
        this.setUnselectedAlpha(1.0f);

        // This lead the onDraw() will be called.
        this.setwillNotDraw(false);

        // The selector rectangle drawable.
        this.mSelectorDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
        this.mTopShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
        this.mBottomShadow = new GradientDrawable(Orientation.BottOM_TOP,SHADOWS_COLORS);

        // The default background.
//        this.setBackgroundResource(R.drawable.wheel_bg);

        // disable the sound effect default.
        this.setSoundEffectsEnabled(true);
    }

/**
 * Initialize.
 *
 * @param context
 */
private void initialize(Context context) {
    this.setVerticalScrollBarEnabled(false);
    this.setSlotInCenter(true);
    this.setorientation(Tosgallery.VERTICAL);
    this.setGravity(Gravity.CENTER_HORIZONTAL);
    this.setUnselectedAlpha(1.0f);

    // This lead the onDraw() will be called.
    this.setwillNotDraw(false);

    // The selector rectangle drawable.
    this.mSelectorDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    this.mTopShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    this.mBottomShadow = new GradientDrawable(Orientation.BottOM_TOP,SHADOWS_COLORS);

    // The default background.
    this.setBackgroundResource(R.drawable.wheel_bg);

    // disable the sound effect default.
    this.setSoundEffectsEnabled(false);
}

@Override
public String translate() {
    AX2JCodeBlock codeBlock = new AX2JCodeBlock(GradientDrawable.class,getRoot().getobjectName());
    for (AX2JNode node : getRoot().getChildren()) {
        if (node.getLabelName().equals("gradient")) {
            String orientation;
            Attribute attribute = node.findAttrByName("android:angle");
            orientation = (attribute == null)? "Orientation.TOP_BottOM" : translateValue(codeBlock,attribute,Integer.class);
            addImport(Orientation.class);
            codeBlock.add("GradientDrawable " + getRoot().getobjectName() + " = new GradientDrawable(" +
                    orientation + ",null);\n",AX2JCode.PRIORITY_SECOND);
        } else if(node.getLabelName().equals("solid")) {
            codeBlock.add("GradientDrawable " + getRoot().getobjectName() + " = new GradientDrawable();\n",AX2JCode.PRIORITY_SECOND);
        }
    }
    addCodeBlock(codeBlock);

    return super.translate();
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    if (topBlurShadow == null) {
        topBlurShadow = new GradientDrawable(Orientation.TOP_BottOM,BLUR_SHADOWS_COLORS);
    }

    if (bottomBlurShadow == null) {
        bottomBlurShadow = new GradientDrawable(Orientation.BottOM_TOP,BLUR_SHADOWS_COLORS);
    }

    if (bottomShadow == null) {
        bottomShadow = new GradientDrawable(Orientation.BottOM_TOP,SHADOWS_COLORS);
    }

}

/**
 * Create a linear gradient shader to show variations in value.
 */
private void setVerValSlider() {
    float[] hsv = new float[3];
    hsv[0] = mHSV[0];
    hsv[1] = mHSV[1];
    hsv[2] = 1;
    int col = Color.HSVToColor(hsv);

    int colors[] = new int[2];
    colors[0] = col;
    colors[1] = 0xFF000000;
    GradientDrawable gradDraw = new GradientDrawable(Orientation.TOP_BottOM,PALETTE_DIM);
    gradDraw.draw(mVerSliderCv);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(
                R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

private ExpiryInfoView(Context paramContext,String paramString)
{
  super(paramContext);
  RelativeLayout.LayoutParams localLayoutParams1 = new RelativeLayout.LayoutParams(-1,-1);
  setBackgroundColor(-1);
  setLayoutParams(localLayoutParams1);
  RelativeLayout.LayoutParams localLayoutParams2 = new RelativeLayout.LayoutParams(-1,(int)TypedValue.applyDimension(1,3.0F,getResources().getdisplayMetrics()));
  localLayoutParams2.addRule(10,-1);
  ImageView localImageView = new ImageView(paramContext);
  localImageView.setLayoutParams(localLayoutParams2);
  int[] arrayOfInt = { -16777216,0 };
  localImageView.setBackgroundDrawable(new GradientDrawable(GradientDrawable.Orientation.TOP_BottOM,arrayOfInt));
  addView(localImageView);
  int i = (int)TypedValue.applyDimension(1,20.0F,getResources().getdisplayMetrics());
  RelativeLayout.LayoutParams localLayoutParams3 = new RelativeLayout.LayoutParams(-1,-2);
  localLayoutParams3.addRule(13,-1);
  localLayoutParams3.setMargins(i,i,i);
  TextView localTextView = new TextView(paramContext);
  localTextView.setGravity(17);
  localTextView.setLayoutParams(localLayoutParams3);
  localTextView.setText(paramString);
  localTextView.setTextColor(-16777216);
  addView(localTextView);
}

/**
 * Inits the.
 */
private void init() {
    l = new char[] {'A',0x99B0B0B0});
    gradientDrawable.setCornerRadius(30);

}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(wheelForeground);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(wheelBackground);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

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

    TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.ColorButton,defStyle,0);
    _color = a.getColor(R.styleable.ColorButton_color,Color.RED);
    a.recycle();

    _highlightDrawable = new GradientDrawable(Orientation.TOP_BottOM,new int[]
            {
                Color.WHITE,Color.TRANSPARENT,Color.TRANSPARENT
            });
    _highlightDrawable.setShape(GradientDrawable.oval);
    _colorDrawable = new GradientDrawable();
    _colorDrawable.setColor(_color);
    _colorDrawable.setShape(GradientDrawable.oval);
}

public ColorButton(Context context,Color.RED);

    _highlightDrawable = new GradientDrawable(Orientation.TOP_BottOM,Color.TRANSPARENT
            });
    _highlightDrawable.setShape(GradientDrawable.oval);
    _colorDrawable = new GradientDrawable();
    _colorDrawable.setColor(_color);
    _colorDrawable.setShape(GradientDrawable.oval);
}

/**
 * Initializes the views.
 *
 * @param rootView View that contains all the content,such as the label,gradient view,etc.
 * @param textResourceId The resource ID of the text to show on the label.
 * @param seekBarMax The range of the seek bar.
 * @param seekBarListener The listener for when the seek bar value changes.
 */
ColorPickerAdvancedComponent(final View rootView,final int textResourceId,final int seekBarMax,final OnSeekBarchangelistener seekBarListener) {
    mGradientView = rootView.findViewById(R.id.gradient);
    mText = (TextView) rootView.findViewById(R.id.text);
    mText.setText(textResourceId);
    mGradientDrawable = new GradientDrawable(GradientDrawable.Orientation.LEFT_RIGHT,null);
    mSeekBar = (SeekBar) rootView.findViewById(R.id.seek_bar);
    mSeekBar.setonSeekBarchangelistener(seekBarListener);
    mSeekBar.setMax(seekBarMax);
    // Setting the thumb offset means the seek bar thumb can move all the way to each end
    // of the gradient view.
    Context context = rootView.getContext();
    int offset = context.getResources()
                        .getDrawable(R.drawable.color_picker_advanced_select_handle)
                        .getIntrinsicWidth();
    mSeekBar.setThumbOffset(offset / 2);
}

/**
 * Initializes resources
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

/**
 * Initializes resources 
 */
private void initResourcesIfNecessary() {
    if (centerDrawable == null) {
        centerDrawable = getContext().getResources().getDrawable(R.drawable.wheel_val);
    }

    if (topShadow == null) {
        topShadow = new GradientDrawable(Orientation.TOP_BottOM,SHADOWS_COLORS);
    }

    setBackgroundResource(R.drawable.wheel_bg);
}

我的标签xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TabHost
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@android:id/tabhost"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >

        <RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical" >

            <FrameLayout
                android:id="@android:id/tabcontent"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:layout_above="@android:id/tabs" />

            <TabWidget
                android:id="@android:id/tabs"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:background="#FFFFFF"
                android:tabStripEnabled="false"
                android:layout_gravity="bottom" />
        </RelativeLayout>
    </TabHost>

</LinearLayout>

TabHost t;
    t.getTabWidget().setStripEnabled(false);
    t.getTabWidget().setDividerDrawable(R.drawable.ic_launcher);