如何在Android中使用執行時許可權在外部儲存中建立txt檔案？

此示例演示如何在Android中使用執行時許可權在外部儲存中建立txt檔案。

步驟1 - 在Android Studio中建立一個新專案，轉到檔案⇒新建專案，並填寫所有必需的詳細資訊以建立新專案。

步驟2 - 將以下程式碼新增到res/layout/activity_main.xml。

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   xmlns:tools = "http://schemas.android.com/tools"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   tools:context = ".MainActivity"
   android:orientation = "vertical">
   <EditText
      android:id = "@+id/enterText"
      android:hint = "Please enter text here"
      android:layout_width = "match_parent"
      android:layout_height = "wrap_content" />
   <Button
      android:id = "@+id/save"
      android:text = "Save"
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content" />
</LinearLayout>

在上面的程式碼中，我們使用了編輯文字和按鈕。當用戶點選按鈕時，它將獲取編輯文字中的資料並將其儲存到外部儲存中。

步驟3 - 將以下程式碼新增到src/MainActivity.java

package com.example.andy.myapplication;

import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {
   private static final int PERMISSION_REQUEST_CODE = 100;
   Button save;

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

      final EditText enterText = findViewById(R.id.enterText);
      save = findViewById(R.id.save);
      save.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (!enterText.getText().toString().isEmpty()) {
               String state = Environment.getExternalStorageState();
               if (Environment.MEDIA_MOUNTED.equals(state)) {
                  if (Build.VERSION.SDK_INT > = 23) {
                     if (checkPermission()) {
                        File sdcard = Environment.getExternalStorageDirectory();
                        File dir = new File(sdcard.getAbsolutePath() + "/text/");
                        dir.mkdir();
                        File file = new File(dir, "sample.txt");
                        FileOutputStream os = null;
                        try {
                           os = new FileOutputStream(file);
                           os.write(enterText.getText().toString().getBytes());
                           os.close();
                        } catch (IOException e) {
                           e.printStackTrace();
                        }
                     } else {
                        requestPermission(); // Code for permission
                     }
                  } else {
                     File sdcard = Environment.getExternalStorageDirectory();
                     File dir = new File(sdcard.getAbsolutePath() + "/text/");
                     dir.mkdir();
                     File file = new File(dir, "sample.txt");
                     FileOutputStream os = null;
                     try {
                        os = new FileOutputStream(file);
                        os.write(enterText.getText().toString().getBytes());
                        os.close();
                     } catch (IOException e) {
                        e.printStackTrace();
                     }
                  }
               }
            }
         }
      });
   }
   private boolean checkPermission() {
      int result = ContextCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE);
      if (result = = PackageManager.PERMISSION_GRANTED) {
         return true;
      } else {
         return false;
      }
   }

   private void requestPermission() {
      if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
      Toast.makeText(MainActivity.this, "Write External Storage permission allows us to create files. Please allow this permission in App Settings.", Toast.LENGTH_LONG).show();
      } else {
         ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, PERMISSION_REQUEST_CODE);
      }
   }

   @Override
   public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
      switch (requestCode) {
         case PERMISSION_REQUEST_CODE:
         if (grantResults.length > 0 && grantResults[0] = = PackageManager.PERMISSION_GRANTED) {
            Log.e("value", "Permission Granted, Now you can use local drive .");
         } else {
            Log.e("value", "Permission Denied, You cannot use local drive .");
         }
         break;
      }
   }
}

步驟4 - 將以下程式碼新增到manifest.xml

<?xml version = "1.0" encoding = "utf-8"?>
<manifest xmlns:android = "http://schemas.android.com/apk/res/android"
   package = "com.example.andy.myapplication">
   <uses-permission android:name = "android.permission.WRITE_EXTERNAL_STORAGE"/>
   <uses-permission android:name = "android.permission.READ_EXTERNAL_STORAGE"/>
   <application
      android:allowBackup = "true"
      android:icon = "@mipmap/ic_launcher"
      android:label = "@string/app_name"
      android:roundIcon = "@mipmap/ic_launcher_round"
      android:supportsRtl = "true"
      android:theme = "@style/AppTheme">
      <activity android:name = ".MainActivity">
         <intent-filter>
            <action android:name = "android.intent.action.MAIN" />
            <category android:name = "android.intent.category.LAUNCHER" />
         </intent-filter>
     </activity>
  </application>
</manifest>

讓我們嘗試執行您的應用程式。我假設您已將您的實際Android移動裝置連線到您的計算機。要從Android Studio執行應用程式，請開啟專案的其中一個活動檔案，然後點選執行工具欄中的圖示。選擇您的移動裝置作為選項，然後檢查您的移動裝置，它將顯示您的預設螢幕 -