android点击查看大图（长按保存图片）

通常会看到点击ImageView弹出一个Dialog上面有一张大图，然后长按大图可以保存，这就好像成为了一个固定的

流程，那么，我们就来实现这一系列的功能。

1.xml文件，特别简单，只有一个ImageView:

<?xml version="1.0" encoding="utf-8"?>

2.MainActivity:

public class MainActivity extends AppCompatActivity {    private ImageView imageView;    private Dialog dialog;    private ImageView mImageView;    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        init();        //小图的点击事件（弹出大图）        imageView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                dialog.show();            }        });    }    private void init() {        imageView = (ImageView) findViewById(R.id.image);        //大图所依附的dialog        dialog = new Dialog(MainActivity.this, R.style.AlertDialog_AppCompat_Light_);        mImageView = getImageView();        dialog.setContentView(mImageView);        //大图的点击事件（点击让他消失）        mImageView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                dialog.dismiss();            }        });        //大图的长按监听        mImageView.setOnLongClickListener(new View.OnLongClickListener() {            @Override            public boolean onLongClick(View v) {                //弹出的“保存图片”的Dialog                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);                builder.setItems(new String[]{getResources().getString(R.string.save_picture)}, new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        saveCroppedImage(((BitmapDrawable) mImageView.getDrawable()).getBitmap());                    }                });                builder.show();                return true;            }        });    }    //保存图片    private void saveCroppedImage(Bitmap bmp) {        File file = new File("/sdcard/myFolder");        if (!file.exists())            file.mkdir();        file = new File("/sdcard/temp.jpg".trim());        String fileName = file.getName();        String mName = fileName.substring(0, fileName.lastIndexOf("."));        String sName = fileName.substring(fileName.lastIndexOf("."));        // /sdcard/myFolder/temp_cropped.jpg        String newFilePath = "/sdcard/myFolder" + "/" + mName + "_cropped" + sName;        file = new File(newFilePath);        try {            file.createNewFile();            FileOutputStream fos = new FileOutputStream(file);            bmp.compress(Bitmap.CompressFormat.JPEG, 50, fos);            fos.flush();            fos.close();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    //动态的ImageView    private ImageView getImageView(){        ImageView iv = new ImageView(this);        //宽高        iv.setLayoutParams(new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));        //设置Padding        iv.setPadding(20,20,20,20);        //imageView设置图片        InputStream is = getResources().openRawResource(R.mipmap.riven);        Drawable drawable = BitmapDrawable.createFromStream(is, null);        iv.setImageDrawable(drawable);        return iv;    }}

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