使用Viewpager制作图片阅读器（4）- 文件夹分类（附上源码）

      源码下载地址：http://download.csdn.net/detail/hewence1/7853405

       我们现在做的是把所有的图片都放在一个list里面的，当比较多的时候显示加载就使用起来就不方便了。本文在上一节的基础上增加一个功能：

       在进入list列表之前把图片的文件夹进行分类，点击对应的文件夹来查看本文件夹里面的内容，而不是查看android设备里面所有的图片。

    先看一下效果

      先新建一个图片文件夹的对应的实例类：

MyPhotoDir.java

public class MyPhotoDir {    private String DirPath;    private ArrayList<MyPhoto> mList = new ArrayList<MyPhoto>();    private Drawable mThumb;    private String Name;        public MyPhotoDir(String dirPath){        DirPath = dirPath;    }    public String getDirPath() {        return DirPath;    }        public void setDirPath(String dirPath) {        DirPath = dirPath;    }    public ArrayList<MyPhoto> getmList() {        return mList;    }    public void setmList(ArrayList<MyPhoto> mList) {        this.mList = mList;    }    public int getCount() {        return mList.size();    }    public Drawable getmThumb() {        if (null == mThumb){            mThumb = createThumb(400 , 400);        }        return mThumb;    }        /**     * 生成缩略图     */    private Drawable createThumb(int width , int height) {        Bitmap output = Bitmap.createBitmap(width, height,                Bitmap.Config.ARGB_8888);        Canvas canvas = new Canvas(output);        canvas.drawARGB(0x99, 0xff,0xff, 0x00);        final Paint paint = new Paint();        final int padding = width / 10;        Bitmap bit0 , bit1 = null , bit2 = null , bit3 = null;        if (mList.size() >= 4){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);            bit2 = ImageLoader.decodeSampledBitmapFromResource(mList.get(2).getPath(), width, height);            bit3 = ImageLoader.decodeSampledBitmapFromResource(mList.get(3).getPath(), width, height);        }else if (mList.size() == 3){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);            bit2 = ImageLoader.decodeSampledBitmapFromResource(mList.get(2).getPath(), width, height);        }else if (mList.size() == 2){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);        }else if (mList.size() == 1){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);        }else{            return null;        }                        canvas.drawBitmap(bit0, new Rect(0, 0, bit0.getWidth(), bit0.getHeight()),                new Rect(padding / 2, padding / 2, width / 2, height / 2), paint);        if (null != bit1){            canvas.drawBitmap(bit1, new Rect(0, 0, bit1.getWidth(), bit1.getHeight()),                    new Rect(width / 2, padding / 2, width - padding / 2, height / 2), paint);         }        if (null != bit2){            canvas.drawBitmap(bit2, new Rect(0, 0, bit2.getWidth(), bit2.getHeight()),                    new Rect(padding / 2, height / 2, width / 2, height - padding / 2), paint);        }        if (null != bit3){            canvas.drawBitmap(bit3, new Rect(0, 0, bit3.getWidth(), bit3.getHeight()),                    new Rect(width / 2, height / 2, width - padding / 2, height - padding / 2), paint);        }                return new BitmapDrawable(output);    }        public void setmThumb(Drawable mThumb) {        this.mThumb = mThumb;    }    public String getName() {        if (TextUtils.isEmpty(Name)){            int index = DirPath.lastIndexOf("/");            Name = DirPath.substring(index + 1);        }        return Name;    }    public void setName(String name) {        Name = name;    }    public void add(MyPhoto photo) {        mList.add(photo);    }        @Override    public boolean equals(Object o) {        LogUtils.w("equals Object o");        if (this == o){            LogUtils.w("equals Object this == o return  true");            return true;        }        if (o instanceof MyPhotoDir){            MyPhotoDir dir = (MyPhotoDir)o;            String pathDir = dir.getDirPath();            LogUtils.w("equals Object dir.getDirPath() = " + pathDir + "this.getDirPath() = " + this.getDirPath());            if (pathDir != null  && pathDir.equals(this.getDirPath())){                LogUtils.w("equals Object path.eques path  return  true");                return true;            }        }        LogUtils.w("equals Object return false");        return false;    }}

其中DirPath是photoDir的唯一标识
里面的List就对应的文件夹下面的所有的图片的列表，每个图片的缩略图都是更加这个list的里面的图片来合成的，合成方法是List的前四张（少于4张就有几张合成几张）图片拼起来的。对应函数：createThumb（）

**     * 生成缩略图     */    private Drawable createThumb(int width , int height) {        Bitmap output = Bitmap.createBitmap(width, height,                Bitmap.Config.ARGB_8888);        Canvas canvas = new Canvas(output);        canvas.drawARGB(0x99, 0xff,0xff, 0x00);        final Paint paint = new Paint();        final int padding = width / 10;        Bitmap bit0 , bit1 = null , bit2 = null , bit3 = null;        if (mList.size() >= 4){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);            bit2 = ImageLoader.decodeSampledBitmapFromResource(mList.get(2).getPath(), width, height);            bit3 = ImageLoader.decodeSampledBitmapFromResource(mList.get(3).getPath(), width, height);        }else if (mList.size() == 3){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);            bit2 = ImageLoader.decodeSampledBitmapFromResource(mList.get(2).getPath(), width, height);        }else if (mList.size() == 2){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);            bit1 = ImageLoader.decodeSampledBitmapFromResource(mList.get(1).getPath(), width, height);        }else if (mList.size() == 1){            bit0 = ImageLoader.decodeSampledBitmapFromResource(mList.get(0).getPath(), width, height);        }else{            return null;        }                        canvas.drawBitmap(bit0, new Rect(0, 0, bit0.getWidth(), bit0.getHeight()),                new Rect(padding / 2, padding / 2, width / 2, height / 2), paint);        if (null != bit1){            canvas.drawBitmap(bit1, new Rect(0, 0, bit1.getWidth(), bit1.getHeight()),                    new Rect(width / 2, padding / 2, width - padding / 2, height / 2), paint);         }        if (null != bit2){            canvas.drawBitmap(bit2, new Rect(0, 0, bit2.getWidth(), bit2.getHeight()),                    new Rect(padding / 2, height / 2, width / 2, height - padding / 2), paint);        }        if (null != bit3){            canvas.drawBitmap(bit3, new Rect(0, 0, bit3.getWidth(), bit3.getHeight()),                    new Rect(width / 2, height / 2, width - padding / 2, height - padding / 2), paint);        }                return new BitmapDrawable(output);    }    

大家可以使用自己的合成方法！

那么在获取数据的时候就要把前面的方法进行修改：

思路如下：

1.在得到文件的全名之后，在得到图片的文件夹的路劲，

2.把MyPhoto尝试加入到列表（DataConfig.mPhotoDirList）分类中

3.在加入列表之前先检查myPhoto对应的文件夹是否已经在DataConfig.mPhotoDirList，

   如果存在的话，就把myPhoto加入到对应的PhotoDir的list中

   如果不存在的话，就根据MyPhoto的文件夹路径new 一个PhotoDir，把PhotoDir加入到DataConfig.mPhotoDirLis，再把MymyPhoto加入到对应的PhotoDir的list中

private void joinItemToDir(MyPhoto photo) {        String stringDir = photo.getPathDir();        MyPhotoDir mPhotoDir = null;        if (!TextUtils.isEmpty(stringDir)){            if (null == (mPhotoDir = findPhotoDir(stringDir)) ){  // 不存在这个目录                mPhotoDir = new MyPhotoDir(stringDir);                DataConfig.mPhotoDirList.add(mPhotoDir);            }             mPhotoDir.add(photo);        }    }            /**     * @return  是否存在这个图片目录     * 不存在的话就返回null     */    private MyPhotoDir findPhotoDir(String pathDir) {        for (MyPhotoDir dir : DataConfig.mPhotoDirList){            if (dir.getDirPath().equals(pathDir)){                return dir;            }        }        return null;    }

得到数据之后就就跟Adapter联系起来，显示UI

布局文件：

<pre name="code" class="java"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="@drawable/photo10" >    <GridView         android:id="@+id/mGridView"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_centerHorizontal="true"        android:horizontalSpacing="20dp"        android:numColumns="3"        android:verticalSpacing="20dp"        >            </GridView>    </RelativeLayout>

设置

Adapter mAdapter = new MyPhoteDirAdapter(DataConfig.mPhotoDirList, MainActivity.this);        mGridView.setAdapter(mAdapter);

MyPhoteDirAdapter.java<pre name="code" class="java">    Context mContext = null;    ArrayList<MyPhotoDir> mList = null;        public MyPhoteDirAdapter(ArrayList<MyPhotoDir> list , Context context){        mList = list;        mContext = context;    }    @Override    public int getCount() {        return mList.size();    }    @Override    public Object getItem(int arg0) {        return mList.get(arg0);    }    @Override    public long getItemId(int arg0) {        return arg0;    }         ViewHolder mHolder = null;    @Override    public View getView(int position, View view, ViewGroup parent) {        ViewHolder mHolder = null;        if (null == view){            view = LayoutInflater.from(mContext).inflate(R.layout.layout_photodir, null);            mHolder = new ViewHolder();            mHolder.mImage = (ImageView)view.findViewById(R.id.photo_thumb);            mHolder.mText = (TextView)view.findViewById(R.id.photo_name);            view.setTag(mHolder);        }else{            mHolder = (ViewHolder)view.getTag();        }        mHolder.mImage.setImageDrawable(mList.get(position).getmThumb());        mHolder.mText.setText(mList.get(position).getName());        return view;    }        public class ViewHolder{        public ImageView mImage = null;        public TextView mText = null;    }

对应布局文件：

<pre name="code" class="html"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >        <ImageView         android:id="@+id/photo_thumb"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:scaleType="fitXY"/>    <TextView         android:id="@+id/photo_name"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:textSize="25dp"        android:textColor="#ffffffff"        android:layout_centerHorizontal="true"        android:layout_below="@id/photo_thumb"/></RelativeLayout>

再加上点击进入对应的文件夹就大功告成了：

mGridView.setOnItemClickListener(new OnItemClickListener() {            @Override            public void onItemClick(AdapterView<?> arg0, View view, int position, long arg3) {                LogUtils.i("onItemClick position = " + position);                Intent it = new Intent(MainActivity.this , MyListActivity.class);                mCurPosition = position;                it.putExtra("index", position);                startActivityForResult(it, REQUEST_MY_LIST);            }        });

点击时把点击的第几个文件传进去 

it.putExtra("index", position);

在MyListActivity接收

Intent it = getIntent();        if (null != it){            index = it.getIntExtra("index", index);        }

主要代码都贴出来了，主要的地方是生成文件的缩略图，跟文件夹的分类