Android_Java(36) - UsingMediaStore

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_marginBottom="10dp">

        <Button
            android:layout_width="0dp"
            android:layout_weight="50"
            android:layout_height="wrap_content"
            android:id="@+id/previous"
            android:backgroundTint="#FF9800"
            android:text="FirstImage"
            android:onClick="displayFirstImage"></Button>
        <Button
            android:layout_width="0dp"
            android:layout_weight="50"
            android:layout_height="wrap_content"
            android:id="@+id/next"
            android:backgroundTint="#009688"
            android:text="LastImage"
            android:onClick="displayLastImage"></Button>
    </LinearLayout>

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/picture"
        android:layout_marginBottom="10dp"></ImageView>

</LinearLayout>

---

package kr.co.usingmediastore;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;

public class MainActivity extends AppCompatActivity {
    private Cursor cursor;
    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setIcon(R.drawable.ic_launcher);

        imageView = findViewById(R.id.picture);

        /*
           Android 10부터 "제한된 저장소(Scoped Storage)" 개념이 적용되기 시작함.
           예전엔 미디어파일(이미지,동영상,오디오파일들) 사용자가 직접 SDCard(외부 저장소)에
           저장가능했으나,
           이젠 MediaStore를 통해 읽거나 쓰도록 권장함
         */
        ActivityCompat.requestPermissions(this,
                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
    }

    public void displayFirstImage(View v) {

        try {
            String[] projection = new String[] {
                    MediaStore.Images.ImageColumns._ID,
                    MediaStore.Images.ImageColumns.DATA
            };

            //컨텐트 제공자를 통해서 이미지를 읽음
            cursor = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                    projection,null,null,null);

            int size = cursor.getCount();
            if (size == 0) {
                Toast.makeText(getApplicationContext(),
                        "장치에 이미가 없음!", Toast.LENGTH_SHORT).show();
            }
            else {
                //첫 번째 이미지를 읽어 화면에 표시함
                if (cursor.moveToFirst()) {
                    String imageLocation = cursor.getString(1);
                    Toast.makeText(getApplicationContext(), imageLocation, Toast.LENGTH_LONG).show();
                    File imageFile = new File(imageLocation);
                    if (imageFile.exists()) {
                        Bitmap bm = BitmapFactory.decodeFile(imageLocation);
                        imageView.setImageBitmap(bm);
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }


    public void displayLastImage(View v) {

        try {
            String[] projection = new String[] {
                    MediaStore.Images.ImageColumns._ID,
                    MediaStore.Images.ImageColumns.DATA,
                    MediaStore.Images.ImageColumns.MIME_TYPE
            };

            //컨텐트 제공자를 통해서 이미지를 읽음
            cursor = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                    projection,null,null,null);

            int size = cursor.getCount();
            if (size == 0) {
                Toast.makeText(getApplicationContext(),
                        "장치에 이미가 없음!", Toast.LENGTH_SHORT).show();
            }
            else {
                //마지막 번째 이미지를 읽어 화면에 표시함
                if (cursor.moveToLast()) {
                    String imageLocation = cursor.getString(1);
                    Toast.makeText(getApplicationContext(), imageLocation, Toast.LENGTH_LONG).show();
                    File imageFile = new File(imageLocation);
                    if (imageFile.exists()) {
                        Bitmap bm = BitmapFactory.decodeFile(imageLocation);
                        imageView.setImageBitmap(bm);
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

---