public String getString(int index) {
        if (mRecycled) {
            throw new RuntimeException("Cannot make calls to a recycled instance!");
        }

        index *= AssetManager.STYLE_NUM_ENTRIES;
        final int[] data = mData;
        final int type = data[index+AssetManager.STYLE_TYPE];
        if (type == TypedValue.TYPE_NULL) {
            return null;
        } else if (type == TypedValue.TYPE_STRING) {
            return loadStringValueAt(index).toString();
        }

        TypedValue v = mValue;
        if (getValueAt(index, v)) {
            Log.w(Resources.TAG, "Converting to string: " + v);
            CharSequence cs = v.coerceToString();
            return cs != null ? cs.toString() : null;
        }
        Log.w(Resources.TAG, "getString of bad type: 0x"
              + Integer.toHexString(type));
        return null;
    }

上面的index要乘以6（STYLE_NUM_ENTRIES），因为是每6个一组的，如果type为null就返回空，如果为String类型就会调用loadStringValueAt方法获取我们设置的值。有一点要注意，如果我们在attrs中设置的format类型和我们自定义设置的参数不符的话，当运行的时候是会报错的，必须要设置相符并clean才能解决。否则就执行下面的方法，强制转换为字符串，代码比较简单，这里就不再贴出。在来看下一个bool类型和int类型的，由于这两个差不多，就随便挑一个

    public int getInt(int index, int defValue) {
        index *= AssetManager.STYLE_NUM_ENTRIES;
        final int[] data = mData;
        final int type = data[index+AssetManager.STYLE_TYPE];
        if (type == TypedValue.TYPE_NULL) {
            return defValue;
        } else if (type >= TypedValue.TYPE_FIRST_INT
            && type <= TypedValue.TYPE_LAST_INT) {
            return data[index+AssetManager.STYLE_DATA];
        }

        TypedValue v = mValue;
        if (getValueAt(index, v)) {
            Log.w(Resources.TAG, "Converting to int: " + v);
            return XmlUtils.convertValueToInt(
                v.coerceToString(), defValue);
        }
        Log.w(Resources.TAG, "getInt of bad type: 0x"
              + Integer.toHexString(type));
        return defValue;
    }

    /** Identifies the start of integer values that were specified as
     *  color constants (starting with '#'). */
    public static final int TYPE_FIRST_COLOR_INT = 0x1c;

    /** The <var>data</var> field holds a color that was originally
     *  specified as #aarrggbb. */
    public static final int TYPE_INT_COLOR_ARGB8 = 0x1c;
    /** The <var>data</var> field holds a color that was originally
     *  specified as #rrggbb. */
    public static final int TYPE_INT_COLOR_RGB8 = 0x1d;
    /** The <var>data</var> field holds a color that was originally
     *  specified as #argb. */
    public static final int TYPE_INT_COLOR_ARGB4 = 0x1e;
    /** The <var>data</var> field holds a color that was originally
     *  specified as #rgb. */
    public static final int TYPE_INT_COLOR_RGB4 = 0x1f;

    /** Identifies the end of integer values that were specified as color
     *  constants. */
    public static final int TYPE_LAST_COLOR_INT = 0x1f;

    /** Identifies the end of plain integer values. */
    public static final int TYPE_LAST_INT = 0x1f;

    public static final int
    convertValueToInt(CharSequence charSeq, int defaultValue)
    {
        if (null == charSeq)
            return defaultValue;

        String nm = charSeq.toString();

        // XXX This code is copied from Integer.decode() so we don't
        // have to instantiate an Integer!

        int value;
        int sign = 1;
        int index = 0;
        int len = nm.length();
        int base = 10;

        if ('-' == nm.charAt(0)) {
            sign = -1;
            index++;
        }

        if ('0' == nm.charAt(index)) {
            //  Quick check for a zero by itself
            if (index == (len - 1))
                return 0;

            char    c = nm.charAt(index + 1);

            if ('x' == c || 'X' == c) {
                index += 2;
                base = 16;
            } else {
                index++;
                base = 8;
            }
        }
        else if ('#' == nm.charAt(index))
        {
            index++;
            base = 16;
        }

        return Integer.parseInt(nm.substring(index), base) * sign;
    }

    public int getColor(int index, int defValue) {
        index *= AssetManager.STYLE_NUM_ENTRIES;
        final int[] data = mData;
        final int type = data[index+AssetManager.STYLE_TYPE];
        if (type == TypedValue.TYPE_NULL) {
            return defValue;
        } else if (type >= TypedValue.TYPE_FIRST_INT
            && type <= TypedValue.TYPE_LAST_INT) {
            return data[index+AssetManager.STYLE_DATA];
        } else if (type == TypedValue.TYPE_STRING) {
            final TypedValue value = mValue;
            if (getValueAt(index, value)) {
                ColorStateList csl = mResources.loadColorStateList(
                        value, value.resourceId);
                return csl.getDefaultColor();
            }
            return defValue;
        }

        throw new UnsupportedOperationException("Can't convert to color: type=0x"
                + Integer.toHexString(type));
    }

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_pressed="true" android:color="@color/blue"/>
    <item android:state_pressed="false" android:state_selected="true" android:color="@color/yellow"/>
    <item android:state_pressed="false" android:state_selected="false" android:color="@color/green"/>

</selector>

    public int getLayoutDimension(int index, String name) {
        index *= AssetManager.STYLE_NUM_ENTRIES;
        final int[] data = mData;
        final int type = data[index+AssetManager.STYLE_TYPE];
        if (type >= TypedValue.TYPE_FIRST_INT
                && type <= TypedValue.TYPE_LAST_INT) {
            return data[index+AssetManager.STYLE_DATA];
        } else if (type == TypedValue.TYPE_DIMENSION) {
            return TypedValue.complexToDimensionPixelSize(
                data[index+AssetManager.STYLE_DATA], mResources.mMetrics);
        }

        throw new RuntimeException(getPositionDescription()
                + ": You must supply a " + name + " attribute.");
    }

        protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) {
            width = a.getLayoutDimension(widthAttr, "layout_width");
            height = a.getLayoutDimension(heightAttr, "layout_height");
        }

    public static int getDefaultSize(int size, int measureSpec) {
        int result = size;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        switch (specMode) {
        case MeasureSpec.UNSPECIFIED:
            result = size;
            break;
        case MeasureSpec.AT_MOST:
        case MeasureSpec.EXACTLY:
            result = specSize;
            break;
        }
        return result;
    }