mediaProvider获取系统图片

 多媒体数据库路径：data/data/com.android.providers.media/database/external.db||internal.db

首先开权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

但是实际上还需要动态申请权限

package com.example.mediaeidaprovierdemo;

import android.Manifest;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.content.Intent;

import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.RemoteException;
import android.provider.MediaStore;
import android.provider.Settings;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.Toast;


import static android.content.pm.PackageManager.PERMISSION_GRANTED;

public class MainActivity extends AppCompatActivity {
    private ContentResolver mProvider;
    private static final int NOT_NOTICE = 2;//如果勾选了不再询问
    private AlertDialog alertDialog;
    private AlertDialog mDialog;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myRequetPermission();
    }

    private void myRequetPermission() {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
        } else {
            run();
            Toast.makeText(this, "您已经申请了权限!", Toast.LENGTH_SHORT).show();
        }
    }

    private void run() {
        ImageView imageView = findViewById(R.id.iv_main_show);
        String filePath;
        mProvider = getContentResolver();
        Cursor cursor = mProvider.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[]{MediaStore.Images.Media.DATA},
                null, null, null, null);
        int columnIndex = cursor.getColumnIndex(MediaStore.Images.Media.DATA);
        if (cursor.moveToFirst()) {
            filePath = cursor.getString(columnIndex);
            Bitmap bitmap = BitmapFactory.decodeFile(filePath);
            imageView.setImageBitmap(bitmap);
        }
        cursor.close();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == NOT_NOTICE) {
            myRequetPermission();//由于不知道是否选择了允许所以需要再次判断
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == 1) {
            for (int i = 0; i < permissions.length; i++) {
                if (grantResults[i] == PERMISSION_GRANTED) {//选择了“始终允许”
                    run();
                    Toast.makeText(this, "" + "权限" + permissions[i] + "申请成功", Toast.LENGTH_SHORT).show();
                } else {
                    if (!ActivityCompat.shouldShowRequestPermissionRationale(this, permissions[i])) {//用户选择了禁止不再询问
                        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                        builder.setTitle("permission")
                                .setMessage("点击允许才可以使用我们的app哦")
                                .setPositiveButton("去允许", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        if (mDialog != null && mDialog.isShowing()) {
                                            mDialog.dismiss();
                                        }
                                        Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
                                        Uri uri = Uri.fromParts("package", getPackageName(), null);//注意就是"package",不用改成自己的包名
                                        intent.setData(uri);
                                        startActivityForResult(intent, NOT_NOTICE);
                                    }
                                });
                        mDialog = builder.create();
                        mDialog.setCanceledOnTouchOutside(false);
                        mDialog.show();
                    } else {//选择禁止
                        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                        builder.setTitle("permission")
                                .setMessage("点击允许才可以使用我们的app哦")
                                .setPositiveButton("去允许", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        if (alertDialog != null && alertDialog.isShowing()) {
                                            alertDialog.dismiss();
                                        }
                                        ActivityCompat.requestPermissions(MainActivity.this,
                                                new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                                    }
                                });
                        alertDialog = builder.create();
                        alertDialog.setCanceledOnTouchOutside(false);
                        alertDialog.show();
                    }
                }
            }
        }
    }
}

由于如果没有权限程序会崩掉所以在申请权限环节做了很多设计   

本文地址：https://blog.csdn.net/we1less/article/details/107885691