Android TypedArray源码详解
尊重原创，转载请标明出处 http://blog.csdn.net/abcdef314159
在自定义控件的时候，如果我们想额外的添加一些属性，就会用到TypedArray这个类，那么这个类是怎么得到的，以及怎么使用的，这篇讲会详细讲解，下面是我以前自定义控件的一段代码
TypedArray typedArray = context.obtainStyledAttributes(attrs,R.styleable.myaccount_item_style); public TypedArray obtainStyledAttributes(AttributeSet set,
int[] attrs, int defStyleAttr, int defStyleRes) {
final int len = attrs.length;
final TypedArray array = TypedArray.obtain(Resources.this, len);
// XXX note that for now we only work with compiled XML files.
// To support generic XML files we will need to manually parse
// out the attributes from the XML file (applying type information
// contained in the resources and such).
final XmlBlock.Parser parser = (XmlBlock.Parser)set;
AssetManager.applyStyle(mTheme, defStyleAttr, defStyleRes,
parser != null ? parser.mParseState : 0, attrs, array.mData, array.mIndices);
array.mTheme = this;
array.mXml = parser;
…………………………
return array;
}
static TypedArray obtain(Resources res, int len) {
final TypedArray attrs = res.mTypedArrayPool.acquire();
if (attrs != null) {
attrs.mLength = len;
attrs.mRecycled = false;
final int fullLen = len * AssetManager.STYLE_NUM_ENTRIES;
if (attrs.mData.length >= fullLen) {
return attrs;
}
attrs.mData = new int[fullLen];
attrs.mIndices = new int[1 + len];
return attrs;
}
return new TypedArray(res,
new int[len*AssetManager.STYLE_NUM_ENTRIES],
new int[1+len], len);
}他首先会从TypedArray池中获取，如果有就取出，mDate的大小不能小于属性个数的6倍，因为STYLE_NUM_ENTRIES的值为6，如果没有就new一个然后返回，把属性的值提取出来之后我们就可以来操作了，我们先来看一下View类初始化中的一段代码
final int N = a.getIndexCount();
for (int i = 0; i < N; i++) {
int attr = a.getIndex(i);
switch (attr) {
case com.android.internal.R.styleable.View_background:
background = a.getDrawable(attr);
break;
…………………………
}
} /*package*/ TypedArray(Resources resources, int[] data, int[] indices, int len) {
mResources = resources;
mMetrics = mResources.mMetrics;
mAssets = mResources.mAssets;
mData = data;
mIndices = indices;
mLength = len;
}
/*package*/ static final int STYLE_NUM_ENTRIES = 6;
/*package*/ static final int STYLE_TYPE = 0;
/*package*/ static final int STYLE_DATA = 1;
/*package*/ static final int STYLE_ASSET_COOKIE = 2;
/*package*/ static final int STYLE_RESOURCE_ID = 3;
/*package*/ static final int STYLE_CHANGING_CONFIGURATIONS = 4;
/*package*/ static final int STYLE_DENSITY = 5; /** The type held by this value, as defined by the constants here.
* This tells you how to interpret the other fields in the object. */
public int type;
/** If the value holds a string, this is it. */
public CharSequence string;
/** Basic data in the value, interpreted according to {@link #type} */
public int data;
/** Additional information about where the value came from; only
* set for strings. */
public int assetCookie;
/** If Value came from a resource, this holds the corresponding resource id. */
public int resourceId;
/** If Value came from a resource, these are the configurations for which
* its contents can change. */
public int changingConfigurations = -1;
/**
* If the Value came from a resource, this holds the corresponding pixel density.
* */
public int density;
/**
* Return the number of values in this array.
*/
public int length() {
if (mRecycled) {
throw new RuntimeException("Cannot make calls to a recycled instance!");
}
return mLength;
}
/**
* Return the number of indices in the array that actually have data.
*/
public int getIndexCount() {
if (mRecycled) {
throw new RuntimeException("Cannot make calls to a recycled instance!");
}
return mIndices[0];
}
public int getIndex(int at) {
if (mRecycled) {
throw new RuntimeException("Cannot make calls to a recycled instance!");
}
return mIndices[1+at];
}
<declare-styleable name="CustomTheme">
<attr name="textView1" format="string" />
<attr name="textView2" format="boolean" />
<attr name="textView3" format="integer" />
<attr name="textView4" format="float" />
<attr name="textView5" format="color" />
<attr name="textView6" format="dimension" />
<attr name="textView7" format="fraction" />
<attr name="textView8" format="reference" />
<attr name="textView9" format="enum" />
<attr name="textView10" format="flags" />
</declare-styleable> private CharSequence loadStringValueAt(int index) {
final int[] data = mData;
final int cookie = data[index+AssetManager.STYLE_ASSET_COOKIE];
if (cookie < 0) {
if (mXml != null) {
return mXml.getPooledString(
data[index+AssetManager.STYLE_DATA]);
}
return null;
}
return mAssets.getPooledStringForCookie(cookie, data[index+AssetManager.STYLE_DATA]);
} private boolean getValueAt(int index, TypedValue outValue) {
final int[] data = mData;
final int type = data[index+AssetManager.STYLE_TYPE];
if (type == TypedValue.TYPE_NULL) {
return false;
}
outValue.type = type;
outValue.data = data[index+AssetManager.STYLE_DATA];
outValue.assetCookie = data[index+AssetManager.STYLE_ASSET_COOKIE];
outValue.resourceId = data[index+AssetManager.STYLE_RESOURCE_ID];
outValue.changingConfigurations = data[index+AssetManager.STYLE_CHANGING_CONFIGURATIONS];
outValue.density = data[index+AssetManager.STYLE_DENSITY];
outValue.string = (type == TypedValue.TYPE_STRING) ? loadStringValueAt(index) : null;
return true;
}
/** Additional information about where the value came from; only
* set for strings. */
public int assetCookie;
/** The <var>string</var> field holds string data. In addition, if
* <var>data</var> is non-zero then it is the string block
* index of the string and <var>assetCookie</var> is the set of
* assets the string came from. */
public static final int TYPE_STRING = 0x03; /*package*/ final CharSequence getPooledStringForCookie(int cookie, int id) {
// Cookies map to string blocks starting at 1.
return mStringBlocks[cookie - 1].get(id);
public final View createView(String name, String prefix, AttributeSet attrs)
throws ClassNotFoundException, InflateException {
Constructor<? extends View> constructor = sConstructorMap.get(name);
Class<? extends View> clazz = null;
try {
…………………………
constructor = clazz.getConstructor(mConstructorSignature);
…………………………
Object[] args = mConstructorArgs;
args[1] = attrs;
constructor.setAccessible(true);
final View view = constructor.newInstance(args);
…………………………
return view;
} catch (NoSuchMethodException e) {
…………………………
} finally {
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
}
} /*package*/ XmlResourceParser loadXmlResourceParser(int id, String type)
throws NotFoundException {
synchronized (mAccessLock) {
TypedValue value = mTmpValue;
if (value == null) {
mTmpValue = value = new TypedValue();
}
getValue(id, value, true);
if (value.type == TypedValue.TYPE_STRING) {
return loadXmlResourceParser(value.string.toString(), id,
value.assetCookie, type);
}
throw new NotFoundException(
"Resource ID #0x" + Integer.toHexString(id) + " type #0x"
+ Integer.toHexString(value.type) + " is not valid");
}
} 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));
}这个就不用多说了，因为color有String和int两种类型，如果是String类型就会返回ColorStateList的默认值，因为ColorStateList可能有好几种类型，但必须都是false的才是默认的，下面随便看一个，下面这些提取之后默认的就是green，因为只有他的所有状态都是false。
<?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;
}
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