前言
非常喜欢用RadioButton+RadioGroup做Tabs，能自动处理选中等效果，但是自带的RadioGroup不支持嵌套RadioButton（从源码可看出仅仅是判断子控件是不是RadioButton），本文参考RadioGroup修改了一个支持嵌套CompoundButton的控件，非常实用。
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正文
/** * 支持嵌套CompoundButton的NestRadioGroup * * @author 农民伯伯 http://www.cnblogs.com/over140/ * */ public class NestRadioGroup extends LinearLayout { // holds the checked id; the selection is empty by default private int mCheckedId = -1; // tracks children radio buttons checked state private CompoundButton.OnCheckedChangeListener mChildOnCheckedChangeListener; // when true, mOnCheckedChangeListener discards events private boolean mProtectFromCheckedChange = false; private OnCheckedChangeListener mOnCheckedChangeListener; private PassThroughHierarchyChangeListener mPassThroughListener; /** * { @inheritDoc } */ public NestRadioGroup(Context context) { super(context); init(); } /** * { @inheritDoc } */ public NestRadioGroup(Context context, AttributeSet attrs) { super(context, attrs); init(); } private void init() { mCheckedId = View.NO_ID; setOrientation(HORIZONTAL); mChildOnCheckedChangeListener = new CheckedStateTracker(); mPassThroughListener = new PassThroughHierarchyChangeListener(); super.setOnHierarchyChangeListener(mPassThroughListener); } /** * { @inheritDoc } */ @Override public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) { // the user listener is delegated to our pass-through listener mPassThroughListener.mOnHierarchyChangeListener = listener; } /** * { @inheritDoc } */ @Override protected void onFinishInflate() { super.onFinishInflate(); // checks the appropriate radio button as requested in the XML file if (mCheckedId != View.NO_ID) { mProtectFromCheckedChange = true; setCheckedStateForView(mCheckedId, true); mProtectFromCheckedChange = false; setCheckedId(mCheckedId); } } /** 递归查找具有选中属性的子控件 */ private static CompoundButton findCheckedView(View child) { if (child instanceof CompoundButton) return (CompoundButton) child; if (child instanceof ViewGroup) { ViewGroup group = (ViewGroup) child; for ( int i = 0, j = group.getChildCount(); i < j; i++) { CompoundButton check = findCheckedView(group.getChildAt(i)); if (check != null) return check; } } return null; // 没有找到 } @Override public void addView(View child, int index, ViewGroup.LayoutParams params) { final CompoundButton view = findCheckedView(child); if (view != null) { if (view.isChecked()) { mProtectFromCheckedChange = true; if (mCheckedId != -1) { setCheckedStateForView(mCheckedId, false); } mProtectFromCheckedChange = false; setCheckedId(view.getId()); } } super.addView(child, index, params); } /** * <p>Sets the selection to the radio button whose identifier is passed in * parameter. Using -1 as the selection identifier clears the selection; * such an operation is equivalent to invoking { @link #clearCheck()}.</p> * * @param id the unique id of the radio button to select in this group * * @see #getCheckedRadioButtonId() * @see #clearCheck() */ public void check( int id) { // don't even bother if (id != -1 && (id == mCheckedId)) { return; } if (mCheckedId != -1) { setCheckedStateForView(mCheckedId, false); } if (id != -1) { setCheckedStateForView(id, true); } setCheckedId(id); } private void setCheckedId( int id) { mCheckedId = id; if (mOnCheckedChangeListener != null) { mOnCheckedChangeListener.onCheckedChanged( this, mCheckedId); } } private void setCheckedStateForView( int viewId, boolean checked) { View checkedView = findViewById(viewId); if (checkedView != null && checkedView instanceof CompoundButton) { ((CompoundButton) checkedView).setChecked(checked); } } /** * <p>Returns the identifier of the selected radio button in this group. * Upon empty selection, the returned value is -1.</p> * * @return the unique id of the selected radio button in this group * * @see #check(int) * @see #clearCheck() * * @attr ref android.R.styleable#NestRadioGroup_checkedButton */ public int getCheckedRadioButtonId() { return mCheckedId; } /** * <p>Clears the selection. When the selection is cleared, no radio button * in this group is selected and { @link #getCheckedRadioButtonId()} returns * null.</p> * * @see #check(int) * @see #getCheckedRadioButtonId() */ public void clearCheck() { check(-1); } /** * <p>Register a callback to be invoked when the checked radio button * changes in this group.</p> * * @param listener the callback to call on checked state change */ public void setOnCheckedChangeListener(OnCheckedChangeListener listener) { mOnCheckedChangeListener = listener; } /** * { @inheritDoc } */ @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new NestRadioGroup.LayoutParams(getContext(), attrs); } /** * { @inheritDoc } */ @Override protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { return p instanceof NestRadioGroup.LayoutParams; } @Override protected LinearLayout.LayoutParams generateDefaultLayoutParams() { return new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); } /** * <p>This set of layout parameters defaults the width and the height of * the children to { @link #WRAP_CONTENT} when they are not specified in the * XML file. Otherwise, this class ussed the value read from the XML file.</p> * * <p>See * { @link android.R.styleable#LinearLayout_Layout LinearLayout Attributes} * for a list of all child view attributes that this class supports.</p> * */ public static class LayoutParams extends LinearLayout.LayoutParams { /** * { @inheritDoc } */ public LayoutParams(Context c, AttributeSet attrs) { super(c, attrs); } /** * { @inheritDoc } */ public LayoutParams( int w, int h) { super(w, h); } /** * { @inheritDoc } */ public LayoutParams( int w, int h, float initWeight) { super(w, h, initWeight); } /** * { @inheritDoc } */ public LayoutParams(ViewGroup.LayoutParams p) { super(p); } /** * { @inheritDoc } */ public LayoutParams(MarginLayoutParams source) { super(source); } /** * <p>Fixes the child's width to * { @link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} and the child's * height to { @link android.view.ViewGroup.LayoutParams#WRAP_CONTENT} * when not specified in the XML file.</p> * * @param a the styled attributes set * @param widthAttr the width attribute to fetch * @param heightAttr the height attribute to fetch */ @Override protected void setBaseAttributes(TypedArray a, int widthAttr, int heightAttr) { if (a.hasValue(widthAttr)) { width = a.getLayoutDimension(widthAttr, "layout_width"); } else { width = WRAP_CONTENT; } if (a.hasValue(heightAttr)) { height = a.getLayoutDimension(heightAttr, "layout_height"); } else { height = WRAP_CONTENT; } } } /** * <p>Interface definition for a callback to be invoked when the checked * radio button changed in this group.</p> */ public interface OnCheckedChangeListener { /** * <p>Called when the checked radio button has changed. When the * selection is cleared, checkedId is -1.</p> * * @param group the group in which the checked radio button has changed * @param checkedId the unique identifier of the newly checked radio button */ public void onCheckedChanged(NestRadioGroup group, int checkedId); } private class CheckedStateTracker implements CompoundButton.OnCheckedChangeListener { public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { // prevents from infinite recursion if (mProtectFromCheckedChange) { return; } mProtectFromCheckedChange = true; if (mCheckedId != -1) { setCheckedStateForView(mCheckedId, false); } mProtectFromCheckedChange = false; int id = buttonView.getId(); setCheckedId(id); } } /** * <p>A pass-through listener acts upon the events and dispatches them * to another listener. This allows the table layout to set its own internal * hierarchy change listener without preventing the user to setup his.</p> */ private class PassThroughHierarchyChangeListener implements ViewGroup.OnHierarchyChangeListener { private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener; /** * { @inheritDoc } */ @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1) public void onChildViewAdded(View parent, View child) { if (parent == NestRadioGroup. this) { CompoundButton view = findCheckedView(child); // 查找子控件 if (view != null) { int id = view.getId(); // generates an id if it's missing if (id == View.NO_ID && Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 ) { id = View.generateViewId(); view.setId(id); } view.setOnCheckedChangeListener(mChildOnCheckedChangeListener); } } if (mOnHierarchyChangeListener != null) { mOnHierarchyChangeListener.onChildViewAdded(parent, child); } } /** * { @inheritDoc } */ public void onChildViewRemoved(View parent, View child) { if (parent == NestRadioGroup. this) { CompoundButton view = findCheckedView(child); // 查找子控件 if (view != null) { view.setOnCheckedChangeListener( null); } } if (mOnHierarchyChangeListener != null) { mOnHierarchyChangeListener.onChildViewRemoved(parent, child); } } }
}
代码说明
代码主要是仿照RadioGroup改写，主要是findCheckedView方法递归查找具有选中属性的子控件。
用法
< com.xxx.ui.view.NestRadioGroup android:id ="@+id/main_radio" android:layout_width ="fill_parent" android:layout_height ="wrap_content" android:gravity ="center" android:orientation ="horizontal" > < RadioButton android:id ="@+id/radio_button0" android:layout_width ="0dip" android:layout_height ="wrap_content" android:layout_weight ="1.0" android:checked ="true" android:text ="@string/bottom_feed" /> < RadioButton android:id ="@+id/radio_button1" android:layout_width ="0dip" android:layout_height ="wrap_content" android:layout_weight ="1.0" android:text ="@string/bottom_square" /> < RelativeLayout android:layout_width ="0dip" android:layout_height ="fill_parent" android:layout_weight ="1.0" android:orientation ="horizontal" > < RadioButton android:id ="@+id/radio_button2" style ="@style/title_tab_text_style" android:layout_width ="wrap_content" android:layout_height ="wrap_content" android:layout_centerInParent ="true" android:text ="@string/bottom_message" /> < ImageView android:id ="@+id/new_message_tips" android:layout_width ="wrap_content" android:layout_height ="wrap_content" android:layout_marginTop ="10dip" android:layout_toRightOf ="@+id/radio_button2" android:src ="@drawable/news_tips_red" /> </ RelativeLayout > </ com.xxx.ui.view.NestRadioGroup >
代码说明
1、实现非常常见的Tabs效果，结合ViewPager来使用，new_message_tips可以是一个类似微信右上角的小红圈，用来提醒有新的消息。
2、View.generateViewId需要4.2以上才能使用，所以最好自己设置id