android - 允许访问 Android 应用程序中授予的文件后，登录按钮不起作用

Question

此问题仅在安装后第一次运行应用程序时存在，在授予访问文件权限后登录按钮不起作用，在下一个应用程序运行时登录按钮正常工作。谁能告诉我与此相关的问题是什么。

为登录 Activity 提供代码

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

    if(Build.VERSION.SDK_INT>=24){
        try{
            Method m = StrictMode.class.getMethod("disableDeathOnFileUriExposure");
            m.invoke(null);
        }catch(Exception e){
            e.printStackTrace();
        }
    }



    int hasWriteContactsPermissionW = ContextCompat.checkSelfPermission(login.this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
    if (hasWriteContactsPermissionW != PackageManager.PERMISSION_GRANTED) {
        if (!ActivityCompat.shouldShowRequestPermissionRationale(login.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
            showMessageOKCancel("You need to allow access to Files", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCompat.requestPermissions(login.this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE_ASK_PERMISSIONS);
                }
            });

            return;
        }
        ActivityCompat.requestPermissions(login.this,
                new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE},
                REQUEST_CODE_ASK_PERMISSIONS);

        return;
    }

    loginbtn = findViewById(R.id.loginbtn);

    loginbtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Log.d("MMMMMM", "CLICKEDDD");

            loginbtn.setVisibility(View.GONE);

            EditText emailtxt = findViewById(R.id.emailtxt);
            String email = emailtxt.getText().toString();

            EditText passtxt = findViewById(R.id.passwordtxt);
            String pass = passtxt.getText().toString();


            GlobalVar.hash = String.valueOf(hashing.md5encrypt(email + pass));

            Connect();
        }
    });

Answer 1

您的代码一开始没有运行。这是因为权限检查器在第一次运行时授予权限时停止执行。我已经复制了您的代码 fragment 并注释了该行

if (hasWriteContactsPermissionW != PackageManager.PERMISSION_GRANTED) {
    if(.....) {
        // .... your code 
    }

    return; // this statement terminates (stops ?) the function
    // solution is to remove this line 
}

// these lines are never reached because of the return; above
loginbtn = findViewById(R.id.loginbtn);

解决方案:

1. 在 onCreate 结束时检查权限
2. 从检查权限的 block 中删除 return;

修改后的代码:

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

 if (Build.VERSION.SDK_INT >= 24) {
  try {
   Method m = StrictMode.class.getMethod("disableDeathOnFileUriExposure");
   m.invoke(null);
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

 // moved this above
 loginbtn = findViewById(R.id.loginbtn);
 loginbtn.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {

   Log.d("MMMMMM", "CLICKEDDD");

   loginbtn.setVisibility(View.GONE);

   EditText emailtxt = findViewById(R.id.emailtxt);
   String email = emailtxt.getText().toString();

   EditText passtxt = findViewById(R.id.passwordtxt);
   String pass = passtxt.getText().toString();


   GlobalVar.hash = String.valueOf(hashing.md5encrypt(email + pass));

   Connect();
  }
 });

 // moved this below
 int hasWriteContactsPermissionW = ContextCompat.checkSelfPermission(login.this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
 if (hasWriteContactsPermissionW != PackageManager.PERMISSION_GRANTED) {
  if (!ActivityCompat.shouldShowRequestPermissionRationale(login.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
   showMessageOKCancel("You need to allow access to Files", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
     ActivityCompat.requestPermissions(login.this, new String[] {
      Manifest.permission.WRITE_EXTERNAL_STORAGE
     }, REQUEST_CODE_ASK_PERMISSIONS);
    }
   });

   return;
  }
  ActivityCompat.requestPermissions(login.this,
   new String[] {
    Manifest.permission.WRITE_EXTERNAL_STORAGE
   },
   REQUEST_CODE_ASK_PERMISSIONS);

  return;
 }

}