增加权限获取

android/app/src/main/java/com/fenghua_student_client/MainActivity.java

 package com.fenghua_student_client;
 
+import android.app.Activity;
+import android.content.pm.PackageManager;
+import android.os.Bundle;
+
+import androidx.core.app.ActivityCompat;
+
 import com.facebook.react.ReactActivity;
 
 public class MainActivity extends ReactActivity {
 
+  //先定义
+  private static final int REQUEST_EXTERNAL_STORAGE = 1;
+
+  private static String[] PERMISSIONS_STORAGE = {
+          "android.permission.READ_EXTERNAL_STORAGE",
+          "android.permission.WRITE_EXTERNAL_STORAGE" };
+
+  //然后通过一个函数来申请
+  private void verifyStoragePermissions(Activity activity) {
+    try {
+      //检测是否有写的权限
+      int permission = ActivityCompat.checkSelfPermission(activity,
+              "android.permission.WRITE_EXTERNAL_STORAGE");
+      if (permission != PackageManager.PERMISSION_GRANTED) {
+        // 没有写的权限，去申请写的权限，会弹出对话框
+        ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,REQUEST_EXTERNAL_STORAGE);
+      }
+    } catch (Exception e) {
+      e.printStackTrace();
+    }
+  }
+
+  @Override
+  protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    // 申请权限
+    verifyStoragePermissions(this);
+  }
+
   /**
    * Returns the name of the main component registered from JavaScript. This is used to schedule
    * rendering of the component.