详解android写一个选择图片的示例代码

 public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener, ImageAdapter.OnImageCheckListener, View.OnClickListener { private static final int CAMERA_CODE = 12; List fileList = new ArrayList<>(); ImageAdapter adapter; GridView gvImage; TextView tvFinish; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); //弹出对话框，加载数据 loadData(); } private void initView() { gvImage = (GridView) findViewById(R.id.gv_image); tvFinish = (TextView) findViewById(R.id.tv_finish); adapter = new ImageAdapter(this, fileList); adapter.setOnImageCheckListener(this); gvImage.setAdapter(adapter); gvImage.setOnItemClickListener(this); gvImage.setOnItemLongClickListener(this); tvFinish.setOnClickListener(this); } private ProgressDialog showProgressDialog() { //弹出对话框 ProgressDialog dialog = new ProgressDialog(this); dialog.setTitle("提示"); dialog.setMessage("正在加载图片，请稍等。。。"); dialog.show(); return dialog; } private void loadData() { final ProgressDialog dialog = showProgressDialog(); //开启线程 new Thread() { @Override public void run() { super.run(); //递归 //从sd卡中获取所有图片 getFile(Environment.getExternalStorageDirectory()); runOnUiThread(new Runnable() { @Override public void run() { dialog.dismiss(); adapter.notifyDataSetChanged(); } }); } }.start(); } public void getFile(File dir) { //1. 获取子目录 File[] files = dir.listFiles(); if (files == null) return; //集合或者数组去点for for (File file : files) { if (file.isDirectory()) getFile(file); else { //加载图片 if (file.getName().endsWith(".png-600") || file.getName().endsWith(".jpg-600")) { fileList.add(file); } } } } File cameraFile; //点击 @Override public void onItemClick(AdapterView parent, View view, int position, long id) { if (position == 0) { //getAbsolutePath返回的路径是没有"/" cameraFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/DCIM/" + System.currentTimeMillis() + ".png-600"); //打开照相机 Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); //照相机需要带数据 intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(cameraFile)); startActivityForResult(intent, CAMERA_CODE); } else { //打开大图 File file = fileList.get(position - 1); //带数据跳转到现实大图 Intent intent = new Intent(this, ShowBigImage.class); intent.putExtra("file", file); startActivity(intent); } } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); Log.e("TAG", resultCode + "---------------------"); if (requestCode == CAMERA_CODE && resultCode == RESULT_OK) { Log.e("TAG", (cameraFile.exists()) + ""); fileList.add(0, cameraFile); adapter.notifyDataSetChanged(); } } //长按 @Override public boolean onItemLongClick(AdapterView parent, View view, int position, long id) { if (position == 0) return false; else { adapter.open(position); } return true; } @Override public void onImageCheck(boolean b) { //b代表 适配器中 有没有勾选的值 tvFinish.setEnabled(b); } @Override public void onClick(View v) { //需要知道有哪些数据被选中 //不能使用泛型，ArrayList才实现了序列化，List没有实现 ArrayList resultList = new ArrayList<>(); //通过适配器中的 为true的 选中的项来加载file SparseBooleanArray booleanArray = adapter.getBooleanArray(); for (int i = 0; i 

 public class ImageAdapter extends ListItemAdapter { private boolean select = false; public void open(int posisiont) { select = true; booleanArray.put(posisiont, true); if (onImageCheckListener != null) onImageCheckListener.onImageCheck(true); this.notifyDataSetChanged(); } public void close() { select = false; booleanArray.clear(); notifyDataSetChanged(); } //position //HashMap map = new HashMap<>(); private SparseBooleanArray booleanArray = new SparseBooleanArray(); public SparseBooleanArray getBooleanArray() { return booleanArray; } public ImageAdapter(Context context, List list) { super(context, list); } @Override public int getCount() { //多出来的就是照相机 return super.getCount() + 1; } //  @Override //  public View getView(int position, View convertView, ViewGroup parent) { //    if (convertView == null) { //      ImageView iv = new ImageView(mContext); //      iv.setScaleType(ImageView.ScaleType.CENTER_CROP); //      iv.setBackgroundColor(Color.argb(0xFF, 0x07, 0x05, 0x18)); //      int width = mContext.getResources().getDisplayMetrics().widthPixels / 3 - 2; //      GridView.LayoutParams params = new GridView.LayoutParams(width, width); //      iv.setPadding(2, 2, 2, 2); //      iv.setLayoutParams(params); //      convertView = iv; //    } //    ImageView iv = (ImageView) convertView; //    if (position == 0) { //      //照相机 //      iv.setImageResource(R.mipmap.camera); //    } else { //      iv.setImageURI(Uri.fromFile(getItem(position - 1))); //    } //    return convertView; //  } @Override public View getView(final int position, View convertView, ViewGroup parent) { ViewHolder holder; if (convertView == null) { convertView = View.inflate(mContext, R.layout.item_image, null); holder = new ViewHolder(convertView); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } if (position == 0) { holder.image.setImageResource(R.mipmap.camera); holder.checkBox.setVisibility(View.GONE); } else { holder.image.setImageURI(Uri.fromFile(getItem(position - 1))); if (select) { holder.checkBox.setVisibility(View.VISIBLE); //当前的需不需要勾选呢 //null Boolean b = booleanArray.get(position); if (b == null || b == false) { holder.checkBox.setChecked(false); } else { holder.checkBox.setChecked(true); } //item点击和布局冲突 holder.checkBox.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Boolean b = booleanArray.get(position); if (b == null || b == false) b = true; else b = false; booleanArray.put(position, b); //判断所有的boolean，如果已经没有一个true 关闭 for (int i = 0; i  3 4 // 0 1 2 3 4 5 boolean isChecked = booleanArray.get(booleanArray.keyAt(i)); Log.e("TAG", "----" + isChecked); Log.e("TAG", booleanArray.toString()); if (isChecked) { //有被勾选的值 if (onImageCheckListener != null) onImageCheckListener.onImageCheck(true); return; } } if (onImageCheckListener != null) onImageCheckListener.onImageCheck(false); //没有被勾选的值了 //关闭 close(); } }); } else { holder.checkBox.setVisibility(View.GONE); } //不能使用onCheck //      holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() { //        @Override //        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { //          booleanArray.put(position, isChecked); //        } //      }); } return convertView; } //回调方法。 //写在需要执行方法的地方 //他实现 在需要返回的地方 public interface OnImageCheckListener { public void onImageCheck(boolean b); } private OnImageCheckListener onImageCheckListener; //alt+insert public void setOnImageCheckListener(OnImageCheckListener onImageCheckListener) { this.onImageCheckListener = onImageCheckListener; } class ViewHolder { ImageView image; CheckBox checkBox; public ViewHolder(View convertView) { image = (ImageView) convertView.findViewById(R.id.iv_image); int width = mContext.getResources().getDisplayMetrics().widthPixels / 3 - 2; RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(width, width); image.setLayoutParams(params); checkBox = (CheckBox) convertView.findViewById(R.id.cb_check); } } } 

 //也可以用 extends 来限制一个泛型的父类 //在类的后面定义一个泛型 public abstract class ListItemAdapter extends BaseAdapter { protected Context mContext; protected List mList; //必须要有上下文，数据 //List List public ListItemAdapter(Context context, List list) { mContext = context; mList = list; } //适配器去加载一个List public void setList(List list) { this.mList = list; notifyDataSetChanged(); } @Override public int getCount() { return mList == null ? 0 : mList.size(); } @Override public T getItem(int position) { return mList.get(position); } @Override public long getItemId(int position) { return position; } } 

 public class ShowBigImage extends AppCompatActivity { @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); ImageView iv = new ImageView(this); File file = (File) getIntent().getSerializableExtra("file"); iv.setImageURI(Uri.fromFile(file)); setContentView(iv); } }