Today’s apps all need a picture selector. There are many open source codes on the Internet, but sometimes the interface needs to be modified according to the needs. Therefore, you must know the principle of the picture selector. The implementation principle of the picture selector is very simple, as long as you use the ContentResolver class. Okay, the usage method is a bit like querying the database through the query function, and also using the getColumnIndex function, the code above
Since you want to get pictures, of course you need permission
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
Define the image class Image.java
public class Image { private String path; private String name; private long time; public Image(String path,String name,long time){ this.path = path; this.name = name; this.time = time; } public Image(){ } public String getPath() { return path; } public void setPath(String path) { this.path = path; } public String getName() { return name; } public void setName(String name) { this.name = name; } public long getTime() { return time; } public void setTime(long time) { this.time = time; } }
Define the folder class Folder.java
public class Folder { private String name; private List<Image> images; public Folder(String name,List<Image> images){ this.name = name; this.images = images; } public String getName() { return name; } public void setName(String name) { this.name = name; } public List<Image> getImages() { return images; } public void setImages(List<Image> images) { this.images = images; } }
MainActivity.java
public class MainActivity extends AppCompatActivity { private String[] denied; private String[] permissions = {Manifest.permission.WRITE_EXTERNAL_STORAGE}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { ArrayList<String> list = new ArrayList<>(); for (int i = 0; i < permissions.length; i++) { if (PermissionChecker.checkSelfPermission(this, permissions[i]) == PackageManager.PERMISSION_DENIED) { list.add(permissions[i]); } } if (list.size() != 0) { denied = new String[list.size()]; for (int i = 0; i < list.size(); i++) { denied[i] = list.get(i); ActivityCompat.requestPermissions(this, denied, 5); } } else { init(); } } } @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { if (requestCode == 5) { boolean isDenied = false; for (int i = 0; i < denied.length; i++) { String permission = denied[i]; for (int j = 0; j < permissions.length; j++) { if (permissions[j].equals(permission)) { if (grantResults[j] != PackageManager.PERMISSION_GRANTED) { isDenied = true; break; } } } } if (isDenied) { Toast.makeText(this, "请开启权限", Toast.LENGTH_SHORT).show(); } else { init(); } } super.onRequestPermissionsResult(requestCode, permissions, grantResults); } private static final String allImage = "全部图片"; private HashMap<String,Folder> imageFolders = new HashMap<>(); private List<String> folders = new ArrayList<>(); private ImageAdapter imageAdapter; private ListView listView; private Button button; private void init(){ systemImages(); RecyclerView recyclerView = findViewById(R.id.recycler_view); recyclerView.setLayoutManager(new GridLayoutManager(this,4)); imageAdapter = new ImageAdapter(this,imageFolders.get(allImage).getImages()); recyclerView.setAdapter(imageAdapter); listView = findViewById(R.id.list_view); listView.setAdapter(new ListViewAdapter(this)); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { String key = folders.get(i); Folder folder = imageFolders.get(key); button.setText(folder.getName()); imageAdapter.setList(folder.getImages()); imageAdapter.notifyDataSetChanged(); listView.setVisibility(View.INVISIBLE); } }); button = findViewById(R.id.button); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { listView.setVisibility(View.VISIBLE); } }); button.setText(allImage); } //获取所有图片 public void systemImages(){ ContentResolver cr = this.getContentResolver(); Cursor cursor = cr.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null, MediaStore.Images.Media.DEFAULT_SORT_ORDER); List<Image> images = new ArrayList<>(); Folder allImageFolder = new Folder(allImage, images); imageFolders.put(allImage,allImageFolder); folders.add(allImage); if (cursor != null) { if (cursor.moveToFirst()) { while (!cursor.isAfterLast()) { String fileName = cursor .getString(cursor .getColumnIndex(MediaStore.Images.Media.DISPLAY_NAME)); String path = cursor.getString(cursor .getColumnIndex(MediaStore.Images.Media.DATA)); Point point = getSize(path); if(isSize(point.x,point.y)){ File file = new File(path); if (accept(file)) { Image image = new Image(path,fileName,file.lastModified()); String key = path.substring(0, path.lastIndexOf(File.separator)); List<Image> list; if (imageFolders.containsKey(key)) { list = imageFolders.get(key).getImages(); } else { list = new ArrayList<>(); Folder folder = new Folder(key.substring(key.lastIndexOf(File.separator) + 1, key.length()), list); imageFolders.put(key, folder); folders.add(key); } list.add(image); images.add(image); } } cursor.moveToNext(); } } if (!cursor.isClosed()) { cursor.close(); } } for (String key : imageFolders.keySet()) { List<Image> list = imageFolders.get(key).getImages(); Collections.sort(list, new FileComparator()); } } //判断是否是图片，没想到好的方法，就用文件名来判断 public boolean accept(File f) { String tmp = f.getName().toLowerCase(); if (tmp.endsWith(".png") || tmp.endsWith(".jpg") || tmp.endsWith(".jpeg") || tmp.endsWith(".gif")) { return true; } return false; } //排序按时间排序 private class FileComparator implements Comparator<Image> { @Override public int compare(Image lhs, Image rhs) { if (lhs.getTime() < rhs.getTime()) { return 1; } else if(lhs.getTime() > rhs.getTime()){ return -1; }else{ return 0; } } } //计算图片大小 private Point getSize(String filePath){ BitmapFactory.Options bmFactoryOptions = new BitmapFactory.Options(); bmFactoryOptions.inJustDecodeBounds = true; BitmapFactory.decodeFile(filePath, bmFactoryOptions); return new Point(bmFactoryOptions.outWidth,bmFactoryOptions.outHeight); } //过滤太小的图片 private boolean isSize(int width,int height){ if(height < 200){ return false; }else if(width < 200){ return false; }else if(width*1.0f / height < 0.5){ return false; }else{ return true; } } //布局 class ImageAdapter extends RecyclerView.Adapter<ImageAdapter.ImageViewHolder>{ private Context context; private List<Image> list; public ImageAdapter(Context context,List<Image> list){ this.context = context; this.list = list; } public void setList(List<Image> list) { this.list = list; } @Override public ImageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { ImageViewHolder holder = new ImageViewHolder(LayoutInflater.from(context).inflate(R.layout.item_image, parent, false)); return holder; } @Override public void onBindViewHolder(ImageViewHolder holder, int position) { Glide.with(context).asBitmap().load(list.get(position).getPath()).thumbnail(0.1f).into(holder.iv); } @Override public int getItemCount() { return list.size(); } class ImageViewHolder extends RecyclerView.ViewHolder { ImageView iv; public ImageViewHolder(View view) { super(view); iv = view.findViewById(R.id.image_view); } } } private class ListViewAdapter extends BaseAdapter { private LayoutInflater inflater = null; private Context context; public ListViewAdapter(Context context) { this.context = context; inflater = LayoutInflater.from(context); } @Override public int getCount() { return folders.size(); } @Override public Object getItem(int position) { return null; } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { final ViewHolder holder; if (convertView == null) { convertView = inflater.inflate(R.layout.item_folder, null); holder = new ViewHolder(); holder.textView = convertView.findViewById(R.id.text_view); holder.imageView = convertView.findViewById(R.id.image_view); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } String key = folders.get(position); Folder folder = imageFolders.get(key); holder.textView.setText(folder.getName()); Glide.with(context).asBitmap().load(folder.getImages().get(0).getPath()).thumbnail(0.1f).into(holder.imageView); return convertView; } private class ViewHolder { TextView textView; ImageView imageView; } } }
systemImages()函数内就是获取图片路径的方法了
activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.selectimage.MainActivity"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <RelativeLayout android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1"> <android.support.v7.widget.RecyclerView android:id="@+id/recycler_view" android:layout_width="match_parent" android:layout_height="match_parent"/> <ListView android:id="@+id/list_view" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#fff" android:visibility="invisible"/> </RelativeLayout> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content"/> </LinearLayout> </android.support.constraint.ConstraintLayout>
item_image.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="wrap_content"> <com.example.selectimage.SquareImageView android:id="@+id/image_view" android:layout_width="match_parent" android:layout_height="wrap_content" android:scaleType="centerCrop" /> </RelativeLayout>
item_folder.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal"> <TextView android:id="@+id/text_view" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="3" /> <com.example.selectimage.SquareImageView android:id="@+id/image_view" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1" android:scaleType="centerCrop" /> </LinearLayout>
SquareImageView.java是为了自适应宽度，使图片为正方形
public class SquareImageView extends ImageView { public SquareImageView(Context context) { super(context); } public SquareImageView(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if(getMeasuredWidth() != 0){ setMeasuredDimension(getMeasuredWidth(),getMeasuredWidth()); } } }
至于Glide可以去网上找教程，很简单的
这只是个简陋的页面，现在可以根据需求来随便更改了