预加载时检查权限。

Author: teach

app/src/main/java/com/donkingliang/imageselectdemo/MainActivity.java

@@ -1,9 +1,13 @@
 package com.donkingliang.imageselectdemo;
 
+import android.Manifest;
 import android.content.Intent;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
 import androidx.recyclerview.widget.GridLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -17,6 +21,7 @@
 public class MainActivity extends AppCompatActivity implements View.OnClickListener {
 
     private static final int REQUEST_CODE = 0x00000011;
+    private static final int PERMISSION_WRITE_EXTERNAL_REQUEST_CODE = 0x00000012;
 
     private RecyclerView rvImage;
     private ImageAdapter mAdapter;
@@ -38,8 +43,16 @@ protected void onCreate(Bundle savedInstanceState) {
         findViewById(R.id.btn_only_take).setOnClickListener(this);
         findViewById(R.id.btn_take_and_clip).setOnClickListener(this);
 
-        //预加载手机图片
-        ImageSelector.preload(this);
+        int hasWriteExternalPermission = ContextCompat.checkSelfPermission(this,
+                Manifest.permission.WRITE_EXTERNAL_STORAGE);
+        if (hasWriteExternalPermission == PackageManager.PERMISSION_GRANTED) {
+            //预加载手机图片。加载图片前，请确保app有读取储存卡权限
+            ImageSelector.preload(this);
+        } else {
+            //没有权限，申请权限。
+            ActivityCompat.requestPermissions(this,
+                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, PERMISSION_WRITE_EXTERNAL_REQUEST_CODE);
+        }
     }
 
     @Override
@@ -53,6 +66,26 @@ protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         }
     }
 
+    /**
+     * 处理权限申请的回调。
+     *
+     * @param requestCode
+     * @param permissions
+     * @param grantResults
+     */
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+        if (requestCode == PERMISSION_WRITE_EXTERNAL_REQUEST_CODE) {
+            if (grantResults.length > 0
+                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                //预加载手机图片
+                ImageSelector.preload(this);
+            } else {
+                //拒绝权限。
+            }
+        }
+    }
+
     @Override
     public void onClick(View v) {
         switch (v.getId()) {

imageselector/src/main/java/com/donkingliang/imageselector/ImageSelectorActivity.java

@@ -676,7 +676,6 @@ public void onClick(DialogInterface dialog, int which) {
      * 从SDCard加载图片。
      */
     private void loadImageForSDCard() {
-       final long time = System.currentTimeMillis();
         ImageModel.loadImageForSDCard(this, new ImageModel.DataCallback() {
             @Override
             public void onSuccess(ArrayList<Folder> folders) {

imageselector/src/main/java/com/donkingliang/imageselector/model/ImageModel.java

@@ -1,7 +1,9 @@
 package com.donkingliang.imageselector.model;
 
+import android.Manifest;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.pm.PackageManager;
 import android.database.ContentObserver;
 import android.database.Cursor;
 import android.net.Uri;
@@ -20,6 +22,8 @@
 import java.util.Collections;
 import java.util.List;
 
+import androidx.core.content.ContextCompat;
+
 public class ImageModel {
 
     /**
@@ -34,14 +38,23 @@ public class ImageModel {
      *
      * @param context
      */
-    public static void preload(final Context context) {
+    public static void preloadAndRegisterContentObserver(final Context context) {
         isNeedCache = true;
         if (observer == null) {
             observer = new PhotoContentObserver(context.getApplicationContext());
             context.getApplicationContext().getContentResolver().registerContentObserver(
                     MediaStore.Images.Media.EXTERNAL_CONTENT_URI, false, observer);
         }
-        loadImageForSDCard(context, true, null);
+        preload(context);
+    }
+
+    private static void preload(final Context context) {
+        int hasWriteExternalPermission = ContextCompat.checkSelfPermission(context,
+                Manifest.permission.WRITE_EXTERNAL_STORAGE);
+        if (hasWriteExternalPermission == PackageManager.PERMISSION_GRANTED) {
+            //有权限，加载图片。
+            loadImageForSDCard(context, true, null);
+        }
     }
 
     /**

imageselector/src/main/java/com/donkingliang/imageselector/utils/ImageSelector.java

@@ -50,7 +50,7 @@ public class ImageSelector {
      * @param context
      */
     public static void preload(Context context) {
-        ImageModel.preload(context);
+        ImageModel.preloadAndRegisterContentObserver(context);
     }
 
     /**