【Android自定义控件】支持多层嵌套RadioButton的RadioGroup

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。 

博客出处：http://www.cnblogs.com/over140/p/3795877.html

/**
 * 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