android自定义RadioGroup实现继承多种布局

       android自带的RadioGroup是继承自LinearLayout，如果布局的时候不是直接在RadioGroup中radiobutton,即radiobutton的父布局不是RadioGroup，这时是查找不到radiobutton的。为了更方便布局，往往radioButton的外面还会包裹一层布局的。如果要实现这种效果，可以自定义一个RadioGroup,于是看了RadioGroup的源码，发现问题在于addView方法和自定义的PassThroughHierarchyChangeListener；

LinearLayout,ConstraintLayout等布局都是继承自viewGroup,要查询它们下面的RadioButton，则在addView方法中增加查询代码。

先拷贝源码，然后去掉RadioGroup(Context context, AttributeSet attrs) 中的方法，新增了一个方法，查找viewGroup控件中的radioButton。

/** 查找radioButton控件
因为往往不是只有一个RadioButton，所以返回一个集合，并且当布局下没有RadioButton时后面也不会报错*/
public List<RadioButton> findRadioButton(ViewGroup group) {
List<RadioButton> resBtns=new ArrayList<>();
int len = group.getChildCount();
for (int i = 0; i < len; i++) {
if (group.getChildAt(i) instanceof RadioButton) {
resBtns.add((RadioButton) group.getChildAt(i));
} else if (group.getChildAt(i) instanceof ViewGroup) {
findRadioButton((ViewGroup) group.getChildAt(i));
}
}
return resBtns;
}

然后在addView方法中使用

@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if (child instanceof RadioButton) {
final RadioButton button = (RadioButton) child;
if (button.isChecked()) {
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
setCheckedId(button.getId());
}
} else if (child instanceof ViewGroup) {//自己的，可查询viewGroup内部的radioButton
final List<RadioButton> buttons = findRadioButton((ViewGroup) child);
for(RadioButton button:buttons) {
if (button.isChecked()) {
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
setCheckedId(button.getId());
}
}
}

super.addView(child, index, params);
}

可以查询到radioButton了，还需要对其进行点击，移除等监听方法、

private class PassThroughHierarchyChangeListener implements
ViewGroup.OnHierarchyChangeListener {
private ViewGroup.OnHierarchyChangeListener mOnHierarchyChangeListener;

public void onChildViewAdded(View parent, View child) {
if (parent == MyRadioGroup.this && child instanceof RadioButton) {
int id = child.getId();
// generates an id if it's missing
if (id == View.NO_ID) {
id = child.hashCode();
child.setId(id);
}
((RadioButton) child)
.setOnCheckedChangeListener(mChildOnCheckedChangeListener);
} else if (parent == MyRadioGroup.this
&& child instanceof ViewGroup) {
List<RadioButton> btns = findRadioButton((ViewGroup) child);
for(RadioButton btn:btns) {
int id = btn.getId();
// generates an id if it's missing
if (id == View.NO_ID) {
id = btn.hashCode();
btn.setId(id);
}
btn.setOnCheckedChangeListener(mChildOnCheckedChangeListener);
}
}

if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewAdded(parent, child);
}
}

public void onChildViewRemoved(View parent, View child) {
if (parent == MyRadioGroup.this && child instanceof RadioButton) {
((RadioButton) child).setOnCheckedChangeListener(null);
} else if (parent == MyRadioGroup.this
&& child instanceof ViewGroup) {

List<RadioButton> btns=findRadioButton((ViewGroup) child);
for(RadioButton btn:btns){
btn.setOnCheckedChangeListener(
null);
}
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
}
}
}其他的可以按照自己的意思来完成布局。这里我继承的是ConstraintLayout，也可以继承其他的布局，看需要。

下面是全部的代码

import android.content.Context;
import android.content.res.TypedArray;
import android.support.constraint.ConstraintLayout;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CompoundButton;
import android.widget.RadioButton;

import java.util.ArrayList;
import java.util.List;

/**
* Created by 墨 on 2018/1/5.
*/

public class MyRadioGroup extends ConstraintLayout {
// 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;

public MyRadioGroup(Context context) {
super(context);
init();
}

public MyRadioGroup(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

private void init() {
mChildOnCheckedChangeListener = new CheckedStateTracker();
mPassThroughListener = new PassThroughHierarchyChangeListener();
super.setOnHierarchyChangeListener(mPassThroughListener);
}

@Override
public void setOnHierarchyChangeListener(OnHierarchyChangeListener listener) {
// the user listener is delegated to our pass-through listener
mPassThroughListener.mOnHierarchyChangeListener = listener;
}

@Override
protected void onFinishInflate() {
super.onFinishInflate();

// checks the appropriate radio button as requested in the XML file
if (mCheckedId != -1) {
mProtectFromCheckedChange = true;
setCheckedStateForView(mCheckedId, true);
mProtectFromCheckedChange = false;
setCheckedId(mCheckedId);
}
}

@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if (child instanceof RadioButton) {
final RadioButton button = (RadioButton) child;
if (button.isChecked()) {
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
setCheckedId(button.getId());
}
} else if (child instanceof ViewGroup) {//自己的，可查询group内部的radioButton
final List<RadioButton> buttons = findRadioButton((ViewGroup) child);
for(RadioButton button:buttons) {
if (button.isChecked()) {
mProtectFromCheckedChange = true;
if (mCheckedId != -1) {
setCheckedStateForView(mCheckedId, false);
}
mProtectFromCheckedChange = false;
setCheckedId(button.getId());
}
}
}

super.addView(child, index, params);
}

/** 查找radioButton控件 */
public List<RadioButton> findRadioButton(ViewGroup group) {
List<RadioButton> resBtns=new ArrayList<>();
int len = group.getChildCount();
for (int i = 0; i < len; i++) {
if (group.getChildAt(i) instanceof RadioButton) {
resBtns.add((RadioButton) group.getChildAt(i));
} else if (group.getChildAt(i) instanceof ViewGroup) {
findRadioButton((ViewGroup) group.getChildAt(i));
}
}
return resBtns;
}

/**
* <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 RadioButton) {
((RadioButton) 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()
*/
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 MyRadioGroup.LayoutParams(getContext(), attrs);
}

/**
* {@inheritDoc}
*/
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof MyRadioGroup.LayoutParams;
}

@Override
protected ConstraintLayout.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>

* Attributes} for a list of all child view attributes that this class
* supports.
* </p>
*
*/
public static class LayoutParams extends ConstraintLayout.LayoutParams {
/**
* {@inheritDoc}
*/
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}

/**
* {@inheritDoc}
*/
public LayoutParams(int w, int h) {
super(w, h);
}

/**
* {@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(MyRadioGroup 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;

public void onChildViewAdded(View parent, View child) {
if (parent == MyRadioGroup.this && child instanceof RadioButton) {
int id = child.getId();
// generates an id if it's missing
if (id == View.NO_ID) {
id = child.hashCode();
child.setId(id);
}
((RadioButton) child)
.setOnCheckedChangeListener(mChildOnCheckedChangeListener);
} else if (parent == MyRadioGroup.this
&& child instanceof ViewGroup) {
List<RadioButton> btns = findRadioButton((ViewGroup) child);
for(RadioButton btn:btns) {
int id = btn.getId();
// generates an id if it's missing
if (id == View.NO_ID) {
id = btn.hashCode();
btn.setId(id);
}
btn.setOnCheckedChangeListener(mChildOnCheckedChangeListener);
}
}

if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewAdded(parent, child);
}
}

public void onChildViewRemoved(View parent, View child) {
if (parent == MyRadioGroup.this && child instanceof RadioButton) {
((RadioButton) child).setOnCheckedChangeListener(null);
} else if (parent == MyRadioGroup.this
&& child instanceof ViewGroup) {

List<RadioButton> btns=findRadioButton((ViewGroup) child);
for(RadioButton btn:btns){
btn.setOnCheckedChangeListener(
null);
}
}
if (mOnHierarchyChangeListener != null) {
mOnHierarchyChangeListener.onChildViewRemoved(parent, child);
}
}
}
}