Android GridView仿微信添加多图效果

 <GridView
  android:id="@+id/gridView"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:columnWidth="90dp"
  android:gravity="center"
  android:horizontalSpacing="4dp"
  android:numColumns="3"
  android:scrollbars="none"
  android:stretchMode="columnWidth"
  android:verticalSpacing="4dp" / 

 //图片数据，ImageItem是图片选择的库自带的Bean
 private ArrayList<ImageItem  images;
 //adapter是核心，添加按钮的处理删除的处理都在里面，后面会说，别急
 private MultiImageAdapter adapter;
 //初次进入的时候先只传this
 adapter = new MultiImageAdapter(this);
 gridView.setAdapter(adapter);

 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  if (data != null && requestCode == 3) {
   //判断一下是否有数据，有的话就addAll()，不会覆盖已经有的图
   if(images == null){
    images = (ArrayList<ImageItem )
      data.getSerializableExtra(ImagePicker.EXTRA_RESULT_ITEMS);
   }else{
    images.addAll((ArrayList<ImageItem )
      data.getSerializableExtra(ImagePicker.EXTRA_RESULT_ITEMS));
   }
   //拿到图片数据后把images传过去
   adapter = new MultiImageAdapter(this,images);
   gridView.setAdapter(adapter);
  } else {
   Toast.makeText(this, "没有选择图片", Toast.LENGTH_SHORT).show();
  }
 }

 <?xml version="1.0" encoding="utf-8"? 
 <com.anfq.mylibrary.view.SquareLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:background="#ffffff"
  android:layout_height="match_parent" 
  <RelativeLayout
   android:layout_width="match_parent"
   android:layout_height="wrap_content" 
   <ImageView
    android:id="@+id/ivIcon"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorPrimaryDark"
    android:scaleType="fitXY" / 
   <ImageButton
    android:id="@+id/ibDelete"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentEnd="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:background="@null"
    android:padding="10dp"
    android:src="@drawable/del" / 
  </RelativeLayout 
  <ImageButton
   android:id="@+id/ibAdd"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:layout_centerInParent="true"
   android:background="#eeeeee"
   android:src="@drawable/add"
   android:visibility="gone" / 
 </com.anfq.mylibrary.view.SquareLayout 

 public class SquareLayout extends RelativeLayout {
  public SquareLayout(Context context, AttributeSet attrs, int defStyle) {
   super(context, attrs, defStyle);
  }
  public SquareLayout(Context context, AttributeSet attrs) {
   super(context, attrs);
  }
  public SquareLayout(Context context) {
   super(context);
  }
  @SuppressWarnings("unused")
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   setMeasuredDimension(getDefaultSize(0, widthMeasureSpec),
     getDefaultSize(0, heightMeasureSpec));
   int childWidthSize = getMeasuredWidth();
   int childHeightSize = getMeasuredHeight();
   // 高度和宽度一样
   heightMeasureSpec = widthMeasureSpec = MeasureSpec.makeMeasureSpec(
     childWidthSize, MeasureSpec.EXACTLY);
   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  }
 }

public class MultiImageAdapter extends BaseAdapter {
private Activity activity;
private LayoutInflater inflater;
private ArrayList<ImageItem  mImages;
//用来判断是否是刚刚进入，刚进入只显示添加按钮，也就是上面java代码中只传this的时候
private boolean is = false;
ImagePicker imagePicker = ImagePicker.getInstance();
public MultiImageAdapter(Activity activity, ArrayList<ImageItem  images) {
this.activity = activity;
this.inflater = LayoutInflater.from(activity);
this.mImages = images;
initImagePicker();//设置图片选择的一些属性
} public MultiImageAdapter(Activity activity) {
this.activity = activity;
this.inflater = LayoutInflater.from(activity);
is = true;//设置为true表示第一次初始化
initImagePicker();//设置图片选择的一些属性
}
@Override
public int getCount() {
if(!is){
//这里判断数据如果有9张就size等于9,否则就+1，+1是为按钮留的位置
return mImages.size()==9?mImages.size():mImages.size()+1;
}
//没有数据就是1，1是为按钮留的位置
return 1;
}
@Override
public Object getItem(int position) {
return mImages.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View view, final ViewGroup parent) {
ViewHolder holder = null;
if (null == view) {
view = inflater.inflate(R.layout.item_ulti_image, null);
holder = new ViewHolder();
holder.ivIcon = (ImageView) view.findViewById(R.id.ivIcon);
holder.ibAdd = (ImageButton) view.findViewById(R.id.ibAdd);
holder.ibDelete = (ImageButton) view.findViewById(R.id.ibDelete);
view.setTag(holder);
} else {
holder = (ViewHolder) view.getTag();
}
if(!is){
//选了图片后会进入这里，先判断下position 是否等于size
if(position == mImages.size()){
//执行到这里就说明是最后一个位置，判断是否有9张图
if(mImages.size() != 9){
//没有9张图就显示添加按钮
holder.ibAdd.setVisibility(View.VISIBLE);
}else{
//有就隐藏
holder.ibAdd.setVisibility(View.GONE);
}
}else{
//还不是最后一个位置的时候执行这里
//隐藏添加按钮，要设置图片嘛~
holder.ibAdd.setVisibility(View.GONE);
//根据条目位置设置图片
ImageItem item = mImages.get(position);
Glide.with(activity)
.load(item.path)
.into(holder.ivIcon);
}
//删除按钮的点击事件
holder.ibDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//移除图片
mImages.remove(position);
//更新
notifyDataSetChanged();
}
});
}else{
//初次初始化的时候显示添加按钮
holder.ibAdd.setVisibility(View.VISIBLE);
}
//添加按钮点击事件
holder.ibAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//判断是否是初始化进入
if(!is){
//到这里表示已经选过了，然后用9-size算出还剩几个图的位置
imagePicker.setSelectLimit(9-mImages.size());//选中数量限制
}
//跳转到图片选择
Intent intent = new Intent(activity, ImageGridActivity.class);
activity.startActivityForResult(intent, 3);
}
});
return view;
}
protected class ViewHolder {
/** icon */
protected ImageView ivIcon;
/** 移除 */
protected ImageButton ibDelete;
/**添加 */
protected ImageButton ibAdd;
}
private void initImagePicker() {
imagePicker.setImageLoader(new GlideImageLoader()); //设置图片加载器
imagePicker.setShowCamera(true);//显示拍照按钮
imagePicker.setCrop(true);//允许裁剪（单选才有效）
imagePicker.setSaveRectangle(true);//是否按矩形区域保存
imagePicker.setSelectLimit(9);//选中数量限制
imagePicker.setStyle(CropImageView.Style.CIRCLE);//裁剪框的形状
imagePicker.setFocusWidth(100);//裁剪框的宽度。单位像素（圆形自动取宽高最小值）
imagePicker.setFocusHeight(100);//裁剪框的高度。单位像素（圆形自动取宽高最小值）
imagePicker.setOutPutX(1000);//保存文件的宽度。单位像素
imagePicker.setOutPutY(1000);//保存文件的高度。单位像素
}
}