Android文件读写权限

首先需要在manifest中添加静态权限

然后在activity的Oncreate方法中，动态申请(6.0以后要求)

//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
public static 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();
    }
}

具体使用是在activity的Oncreate方法中

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContextView(R.layout.activity_main);
    verifyStoragePermissions(this);
    
    ...
    
}

参考
Android 添加读写外部存储权限