Android 使用HorizontalScrollView 实现Gallery效果

　　Gallery（画廊）是一个锁定中心条目并且拥有水平滚动列表的视图，一般用来浏览图片，并且可以响应事件显示信息；Gallery还可以和ImageSwitcher组件结合使用来实现一个通过缩略图来浏览图片的效果；

　　但Gallery被谷歌废弃了，Google推荐使用ViewPager和HorizontalScrollView来实现Gallery的效果；

（1）看一个例子：用Gallery来实现：

代码：

ScrollView1.java

package com.xiaozhang.dialog;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;

public class ScrollView1 extends Activity {

    private Gallery gallery;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.view);
        gallery = (Gallery) findViewById(R.id.gallery);
        // 设置图片适配器
        gallery.setAdapter(new ImageAdapter(this));
        // 设置监听器
        gallery.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View v,
                    int position, long id) {
                Toast.makeText(ScrollView1.this,
                        "点击了第" + (position + 1) + "张图片", Toast.LENGTH_LONG)
                        .show();
            }
        });
    }
}

class ImageAdapter extends BaseAdapter {
    // 声明Context
    private Context context;
    // 图片源数组
    private Integer[] imageInteger = { R.drawable.pic1, R.drawable.pic2,
            R.drawable.pic3, R.drawable.pic4, R.drawable.pic5, R.drawable.pic6,
            R.drawable.pic7 };

    // 声明 ImageAdapter
    public ImageAdapter(Context c) {
        context = c;
    }

    @Override
    // 获取图片的个数
    public int getCount() {
        return imageInteger.length;
    }

    @Override
    // 获取图片在库中的位置
    public Object getItem(int position) {
        return position;
    }

    @Override
    // 获取图片在库中的位置
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ImageView imageView = new ImageView(context);
        // 给ImageView设置资源
        imageView.setImageResource(imageInteger[position]);
        // 设置比例类型
        imageView.setScaleType(ImageView.ScaleType.CENTER);

        imageView.setLayoutParams(new Gallery.LayoutParams(350, 350));
        return imageView;
    }
}

view.xml

<?xml version="1.0" encoding="utf-8"?>
<Gallery xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/gallery"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?android:galleryItemBackground"
    android:spacing="10dp"
    />

用HorizontalScrollView来实现：

MainActivity.java

package com.xiaozhang.horizontal;

import android.app.Activity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

    private LinearLayout mGallery;
    private int[] imgId;
    private LayoutInflater mInflater;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        mInflater = LayoutInflater.from(this);

        imgId = new int[] { R.drawable.pic1, R.drawable.pic2, R.drawable.pic3,
                R.drawable.pic4, R.drawable.pic5, R.drawable.pic6,
                R.drawable.pic7, R.drawable.pic8, R.drawable.pic9 };
        initView();
    }

    private void initView() {
        mGallery = (LinearLayout) findViewById(R.id.gallery_id);

        for (int i = 0; i < imgId.length; i++) {

            View view = mInflater.inflate(R.layout.gallery, mGallery, false);
            ImageView img = (ImageView) view.findViewById(R.id.gallery_image);
            img.setImageResource(imgId[i]);
            TextView txt = (TextView) view.findViewById(R.id.gallery_text);
            txt.setText("some info ");
            mGallery.addView(view);
        }
    }
}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <HorizontalScrollView
        android:layout_width="wrap_content"
        android:layout_height="260dp"
        android:layout_gravity="center_vertical"
        android:background="#AA4444"
        android:scrollbars="none" >

        <LinearLayout
            android:id="@+id/gallery_id"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:orientation="horizontal" >
        </LinearLayout>
    </HorizontalScrollView>

</LinearLayout>

gallery.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="240dp"
    android:layout_height="240dp"
    android:background="@android:color/white" >

    <ImageView
        android:id="@+id/gallery_image"
        android:layout_width="180dp"
        android:layout_height="180dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_margin="5dp"
        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/gallery_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/gallery_image"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        android:textColor="#ff0000"
        android:textSize="25sp" />

</RelativeLayout>

（2）看另一个例子：滑动下面的小图查看大图片；

　　先用Gallery来实现；

实现方式：

MainActivity.java

package com.xiaozhang.dialog;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Gallery.LayoutParams;
import android.widget.ViewSwitcher.ViewFactory;

public class MainActivity extends Activity implements OnItemSelectedListener,
        ViewFactory {

    private ImageSwitcher mSwitcher;
    // 小图片
    private Integer[] mThumbIds = { R.drawable.pic1, R.drawable.pic2,
            R.drawable.pic3, R.drawable.pic4, R.drawable.pic5, R.drawable.pic6,
            R.drawable.pic7, R.drawable.pic8 };
    // 大图片
    private Integer[] mImageIds = { R.drawable.pic1, R.drawable.pic2,
            R.drawable.pic3, R.drawable.pic4, R.drawable.pic5, R.drawable.pic6,
            R.drawable.pic7, R.drawable.pic8 };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 设置窗口无标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
        // 注意在使用一个ImageSwitcher之前，
        // 一定要调用setFactory方法，要不setImageResource这个方法会报空指针异常。
        mSwitcher.setFactory(this);
        // 设置动画效果
        mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
        mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));

        Gallery g = (Gallery) findViewById(R.id.gallery);

        // 添加OnItemSelectedListener监听器
        g.setAdapter(new ImageAdapter(this));
        g.setOnItemSelectedListener(this);

    }

    // 创建内部类ImageAdapter
    public class ImageAdapter extends BaseAdapter {
        public ImageAdapter(Context c) {
            mContext = c;
        }

        public int getCount() {
            return mThumbIds.length;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i = new ImageView(mContext);

            i.setImageResource(mThumbIds[position]);
            // 设置边界对齐
            i.setAdjustViewBounds(true);
            // 设置布局参数
            i.setLayoutParams(new Gallery.LayoutParams(
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            // 设置背景资源
            i.setBackgroundResource(R.drawable.pic1);
            return i;
        }

        private Context mContext;
    }

    @Override
    // 实现onItemSelected()方法，更换图片
    public void onItemSelected(AdapterView<?> adapter, View v, int position,
            long id) {
        // 设置图片资源
        mSwitcher.setImageResource(mImageIds[position]);
    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {

    }

    @Override
    // 实现makeView()方法，为ImageView设置布局格式
    public View makeView() {
        ImageView i = new ImageView(this);
        // 设置背景颜色
        i.setBackgroundColor(0xFF0000);
        // 设置比例类型
        i.setScaleType(ImageView.ScaleType.FIT_CENTER);
        // 设置布局参数
        i.setLayoutParams(new ImageSwitcher.LayoutParams(
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        return i;
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageSwitcher
        android:id="@+id/switcher"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" />

    <Gallery
        android:id="@+id/gallery"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:background="#550000"
        android:gravity="center_vertical"
        android:spacing="16dp" />

</RelativeLayout>

而利用HorizontalScrollView的实现方式为：

代码实现：

HorizontalScrollViewAdapter.java

package com.example.zhy_horizontalscrollview;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

public class HorizontalScrollViewAdapter {

    private LayoutInflater mInflater;
    private List<Integer> mDatas;

    public HorizontalScrollViewAdapter(Context context, List<Integer> mDatas) {
        mInflater = LayoutInflater.from(context);
        this.mDatas = mDatas;
    }

    public int getCount() {
        return mDatas.size();
    }

    public Object getItem(int position) {
        return mDatas.get(position);
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            viewHolder = new ViewHolder();
            convertView = mInflater.inflate(
                    R.layout.activity_index_gallery_item, parent, false);
            viewHolder.mImg = (ImageView) convertView
                    .findViewById(R.id.id_index_gallery_item_image);
            viewHolder.mText = (TextView) convertView
                    .findViewById(R.id.id_index_gallery_item_text);

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        viewHolder.mImg.setImageResource(mDatas.get(position));
        viewHolder.mText.setText("some info ");

        return convertView;
    }

    private class ViewHolder {
        ImageView mImg;
        TextView mText;
    }

}

MainActivity.java

package com.example.zhy_horizontalscrollview;

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

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;

import com.example.zhy_horizontalscrollview.MyHorizontalScrollView.CurrentImageChangeListener;
import com.example.zhy_horizontalscrollview.MyHorizontalScrollView.OnItemClickListener;

public class MainActivity extends Activity {

    private MyHorizontalScrollView mHorizontalScrollView;
    private HorizontalScrollViewAdapter mAdapter;
    private ImageView mImg;
    private List<Integer> mDatas = new ArrayList<Integer>(Arrays.asList(
            R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d,
            R.drawable.e, R.drawable.f, R.drawable.g, R.drawable.h,
            R.drawable.l));

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        mImg = (ImageView) findViewById(R.id.id_content);

        mHorizontalScrollView = (MyHorizontalScrollView) findViewById(R.id.id_horizontalScrollView);
        mAdapter = new HorizontalScrollViewAdapter(this, mDatas);
        // 添加滚动回调
        mHorizontalScrollView
                .setCurrentImageChangeListener(new CurrentImageChangeListener() {
                    @Override
                    public void onCurrentImgChanged(int position,
                            View viewIndicator) {
                        mImg.setImageResource(mDatas.get(position));
                        viewIndicator.setBackgroundColor(Color
                                .parseColor("#AA024DA4"));
                    }
                });
        // 添加点击回调
        mHorizontalScrollView.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onClick(View view, int position) {
                mImg.setImageResource(mDatas.get(position));
                view.setBackgroundColor(Color.parseColor("#AA024DA4"));
            }
        });
        // 设置适配器
        mHorizontalScrollView.initDatas(mAdapter);
    }

}

MyHorizontalScrollView.java

package com.example.zhy_horizontalscrollview;

import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.graphics.Color;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;

public class MyHorizontalScrollView extends HorizontalScrollView implements
        OnClickListener {

    /**
     * 图片滚动时的回调接口
     *
     * @author zhy
     *
     */
    public interface CurrentImageChangeListener {
        void onCurrentImgChanged(int position, View viewIndicator);
    }

    /**
     * 条目点击时的回调
     *
     * @author zhy
     *
     */
    public interface OnItemClickListener {
        void onClick(View view, int pos);
    }

    private CurrentImageChangeListener mListener;

    private OnItemClickListener mOnClickListener;

    private static final String TAG = "MyHorizontalScrollView";

    /**
     * HorizontalListView中的LinearLayout
     */
    private LinearLayout mContainer;

    /**
     * 子元素的宽度
     */
    private int mChildWidth;
    /**
     * 子元素的高度
     */
    private int mChildHeight;
    /**
     * 当前最后一张图片的index
     */
    private int mCurrentIndex;
    /**
     * 当前第一张图片的下标
     */
    private int mFristIndex;
    /**
     * 当前第一个View
     */
    private View mFirstView;
    /**
     * 数据适配器
     */
    private HorizontalScrollViewAdapter mAdapter;
    /**
     * 每屏幕最多显示的个数
     */
    private int mCountOneScreen;
    /**
     * 屏幕的宽度
     */
    private int mScreenWitdh;

    /**
     * 保存View与位置的键值对
     */
    private Map<View, Integer> mViewPos = new HashMap<View, Integer>();

    public MyHorizontalScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // 获得屏幕宽度
        WindowManager wm = (WindowManager) context
                .getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics outMetrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(outMetrics);
        mScreenWitdh = outMetrics.widthPixels;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mContainer = (LinearLayout) getChildAt(0);
    }

    /**
     * 加载下一张图片
     */
    protected void loadNextImg() {
        // 数组边界值计算
        if (mCurrentIndex == mAdapter.getCount() - 1) {
            return;
        }
        // 移除第一张图片，且将水平滚动位置置0
        scrollTo(0, 0);
        mViewPos.remove(mContainer.getChildAt(0));
        mContainer.removeViewAt(0);

        // 获取下一张图片，并且设置onclick事件，且加入容器中
        View view = mAdapter.getView(++mCurrentIndex, null, mContainer);
        view.setOnClickListener(this);
        mContainer.addView(view);
        mViewPos.put(view, mCurrentIndex);

        // 当前第一张图片小标
        mFristIndex++;
        // 如果设置了滚动监听则触发
        if (mListener != null) {
            notifyCurrentImgChanged();
        }

    }

    /**
     * 加载前一张图片
     */
    protected void loadPreImg() {
        // 如果当前已经是第一张，则返回
        if (mFristIndex == 0)
            return;
        // 获得当前应该显示为第一张图片的下标
        int index = mCurrentIndex - mCountOneScreen;
        if (index >= 0) {
            // mContainer = (LinearLayout) getChildAt(0);
            // 移除最后一张
            int oldViewPos = mContainer.getChildCount() - 1;
            mViewPos.remove(mContainer.getChildAt(oldViewPos));
            mContainer.removeViewAt(oldViewPos);

            // 将此View放入第一个位置
            View view = mAdapter.getView(index, null, mContainer);
            mViewPos.put(view, index);
            mContainer.addView(view, 0);
            view.setOnClickListener(this);
            // 水平滚动位置向左移动view的宽度个像素
            scrollTo(mChildWidth, 0);
            // 当前位置--，当前第一个显示的下标--
            mCurrentIndex--;
            mFristIndex--;
            // 回调
            if (mListener != null) {
                notifyCurrentImgChanged();

            }
        }
    }

    /**
     * 滑动时的回调
     */
    public void notifyCurrentImgChanged() {
        // 先清除所有的背景色，点击时会设置为蓝色
        for (int i = 0; i < mContainer.getChildCount(); i++) {
            mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
        }

        mListener.onCurrentImgChanged(mFristIndex, mContainer.getChildAt(0));

    }

    /**
     * 初始化数据，设置数据适配器
     *
     * @param mAdapter
     */
    public void initDatas(HorizontalScrollViewAdapter mAdapter) {
        this.mAdapter = mAdapter;
        mContainer = (LinearLayout) getChildAt(0);
        // 获得适配器中第一个View
        final View view = mAdapter.getView(0, null, mContainer);
        mContainer.addView(view);

        // 强制计算当前View的宽和高
        if (mChildWidth == 0 && mChildHeight == 0) {
            int w = View.MeasureSpec.makeMeasureSpec(0,
                    View.MeasureSpec.UNSPECIFIED);
            int h = View.MeasureSpec.makeMeasureSpec(0,
                    View.MeasureSpec.UNSPECIFIED);
            view.measure(w, h);
            mChildHeight = view.getMeasuredHeight();
            mChildWidth = view.getMeasuredWidth();
            Log.e(TAG, view.getMeasuredWidth() + "," + view.getMeasuredHeight());
            mChildHeight = view.getMeasuredHeight();
            // 计算每次加载多少个View
            mCountOneScreen = (mScreenWitdh / mChildWidth == 0) ? mScreenWitdh
                    / mChildWidth + 1 : mScreenWitdh / mChildWidth + 2;

            Log.e(TAG, "mCountOneScreen = " + mCountOneScreen
                    + " ,mChildWidth = " + mChildWidth);

        }
        // 初始化第一屏幕的元素
        initFirstScreenChildren(mCountOneScreen);
    }

    /**
     * 加载第一屏的View
     *
     * @param mCountOneScreen
     */
    public void initFirstScreenChildren(int mCountOneScreen) {
        mContainer = (LinearLayout) getChildAt(0);
        mContainer.removeAllViews();
        mViewPos.clear();

        for (int i = 0; i < mCountOneScreen; i++) {
            View view = mAdapter.getView(i, null, mContainer);
            view.setOnClickListener(this);
            mContainer.addView(view);
            mViewPos.put(view, i);
            mCurrentIndex = i;
        }

        if (mListener != null) {
            notifyCurrentImgChanged();
        }

    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        switch (ev.getAction()) {
        case MotionEvent.ACTION_MOVE:
            // Log.e(TAG, getScrollX() + "");

            int scrollX = getScrollX();
            // 如果当前scrollX为view的宽度，加载下一张，移除第一张
            if (scrollX >= mChildWidth) {
                loadNextImg();
            }
            // 如果当前scrollX = 0， 往前设置一张，移除最后一张
            if (scrollX == 0) {
                loadPreImg();
            }
            break;
        }
        return super.onTouchEvent(ev);
    }

    @Override
    public void onClick(View v) {
        if (mOnClickListener != null) {
            for (int i = 0; i < mContainer.getChildCount(); i++) {
                mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
            }
            mOnClickListener.onClick(v, mViewPos.get(v));
        }
    }

    public void setOnItemClickListener(OnItemClickListener mOnClickListener) {
        this.mOnClickListener = mOnClickListener;
    }

    public void setCurrentImageChangeListener(
            CurrentImageChangeListener mListener) {
        this.mListener = mListener;
    }

}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="vertical" >

    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1" >

        <ImageView
            android:id="@+id/id_content"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:scaleType="centerCrop"
            android:src="@drawable/ic_launcher" />
    </FrameLayout>

    <com.example.zhy_horizontalscrollview.MyHorizontalScrollView
        android:id="@+id/id_horizontalScrollView"
        android:layout_width="wrap_content"
        android:layout_height="150dp"
        android:layout_gravity="bottom"
        android:background="@android:color/white"
        android:scrollbars="none" >

        <LinearLayout
            android:id="@+id/id_gallery"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:orientation="horizontal" >
        </LinearLayout>
    </com.example.zhy_horizontalscrollview.MyHorizontalScrollView>

</LinearLayout>

activity_index_gallery_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="120dp"
    android:layout_height="130dp"
    android:background="@android:color/white" >

    <ImageView
        android:id="@+id/id_index_gallery_item_image"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_margin="5dp"
        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/id_index_gallery_item_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/id_index_gallery_item_image"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        android:textColor="#ff0000"
        android:textSize="12dp" />

</RelativeLayout>

其中第二个是转载自：

http://blog.csdn.net/lmj623565791/article/details/38140505

多谢群主；