获取库的所有图片(Get all Images in Gallery )

我正在开发中，我想，当用户点击按钮“选择图片”，它应该能够查看绘制文件夹的所有图像gallaryview或GridView控件的应用程序。我怎样才能做到这一点？然后点击来自电网或画廊观看图片后，我只是混帐该图像路径和存储到一个变量。我也希望，当我回去的前一页，我有我与图像路径的所有数据。

public class GetImageActivity extends Activity {

    private static final int SELECT_PICTURE = 1;

    private String selectedImagePath;
    private ImageView img;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        img = (ImageView)findViewById(R.id.ImageView01);

        ((Button) findViewById(R.id.Button01))
                .setOnClickListener(new OnClickListener() {
                    public void onClick(View arg0) {
                        Intent intent = new Intent();
                        intent.setType("image/*");
                        intent.setAction(Intent.ACTION_GET_CONTENT);
                        startActivityForResult(Intent.createChooser(intent,"Select Picture"), SELECT_PICTURE);
                    }
                });
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            if (requestCode == SELECT_PICTURE) {
                Uri selectedImageUri = data.getData();
                selectedImagePath = getPath(selectedImageUri);
                System.out.println("Image Path : " + selectedImagePath);
                img.setImageURI(selectedImageUri);
            }
        }
    }

    public String getPath(Uri uri) {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = managedQuery(uri, projection, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        return cursor.getString(column_index);
    }
}