【Android】寫入與讀取SD卡上的*.txt文件檔

各位Android安卓開發者大家好 ^^

小黑人今天要與大家分享的是針對SD卡上進行文字儲存與檔案讀取，簡單的來說就是將文字字串存入SD-Card裡的txt文件檔，其中包含建立路徑與文字寫入；而讀取的部分就是取得SD-Card上的txt文件檔內容，其中也包含檔案位置判斷與資料取出；看是一個很實用卻又好像不常使用到的範例小黑人就與大家一同分享，讓我們共同看下去吧。

 1. 首先我們要先在AndroidManifest.xml加入SD卡的使用權限，讓我們可以寫入資料與讀取資料。
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

2. 再來我們建立一個簡單的Layout就好，因為重點是在*.java檔中進行。
<LinearLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="20dip"
android:layout_gravity="center_vertical"
android:gravity="center_vertical"
> 

    <TextView

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:text="儲存文字 : "

    />

    <EditText

    android:id="@+id/edit"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:hint="請輸入儲存文字"

    />

    <Button

    android:id="@+id/setBtn"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:text="文字儲存至SD卡"

    />

    <TextView

    android:layout_width="match_parent"

    android:layout_height="1dip"

    android:background="#000000"

    android:layout_marginTop="40dip"

    android:layout_marginBottom="40dip"

    />

    <TextView

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:text="讀取文字 : "

    />

    <TextView

    android:id="@+id/text"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    />

    <Button

    android:id="@+id/getBtn"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:text="讀取SD卡文字"

    />

</LinearLayout>

3. 最後在*.java檔進行存入讀取解析的動作就完成囉。
public class MainActivity extends Activity

{

        //寫入按鈕與讀取按鈕

        private Button mSetBtn, mGetBtn;

        //輸入儲存文字的EditText

        private EditText mEdit;

        //顯示讀取文字的TextView

        private TextView mText;

        @Override

        protected void onCreate(Bundle savedInstanceState)

        {

                super.onCreate(savedInstanceState);

                setContentView(R.layout.main);

                mSetBtn = (Button) findViewById(R.id.setBtn);

                mEdit = (EditText) findViewById(R.id.edit);

                mGetBtn = (Button) findViewById(R.id.getBtn);

                mText = (TextView) findViewById(R.id.text);

                mSetBtn.setOnClickListener(new OnClickListener()

                {

                        @Override

                        public void onClick(View v)

                        {

                                try

                                {

                                   File mSDFile = null;

                                       

                             //檢查有沒有SD卡裝置

                             if(Environment.getExternalStorageState().equals( Environment.MEDIA_REMOVED))

                             {

                               Toast.makeText(MainActivity.this , "沒有SD卡!!!" , Toast.LENGTH_SHORT ).show();

                               return ;

                             }

                             else 

                             {

                               //取得SD卡儲存路徑

                               mSDFile = Environment.getExternalStorageDirectory();

                               }

                             //建立文件檔儲存路徑

                             File mFile = new File(mSDFile.getParent() + "/" + mSDFile.getName() + "/MyAndroid");

                             //若沒有檔案儲存路徑時則建立此檔案路徑

                             if(!mFile.exists())

                             {

                                 mFile.mkdirs();

                             }

                             //取得mEdit文字並儲存寫入至SD卡文件裡

                             FileWriter mFileWriter = new FileWriter( mSDFile.getParent() + "/" + mSDFile.getName() + "/MyAndroid/Pubby.txt" );

                             mFileWriter.write(mEdit.getText().toString());

                             mFileWriter.close();

                             Toast.makeText(MainActivity.this, "已儲存文字", Toast.LENGTH_SHORT).show();

                                }

                                catch (Exception e)

                                {

                                }

                        }

                });

                mGetBtn.setOnClickListener(new OnClickListener()

                {

                        @Override

                        public void onClick(View v)

                        {

                                try

                                {

                                   //取得SD卡儲存路徑

                                   File mSDFile = Environment.getExternalStorageDirectory();

                                   //讀取文件檔路徑

                                   FileReader mFileReader = new FileReader(mSDFile.getParent() + "/" + mSDFile.getName() + "/MyAndroid/Pubby.txt");

                                   BufferedReader mBufferedReader = new BufferedReader(mFileReader);

                                   String mReadText = "";

                                   String mTextLine = mBufferedReader.readLine();

                                   //一行一行取出文字字串裝入String裡，直到沒有下一行文字停止跳出

                                   while (mTextLine!=null)

                                   {

                                           mReadText += mTextLine+"\n";

                                           mTextLine = mBufferedReader.readLine();

                                   }

                                   //文字放入mText裡，並清空mEdit

                                  mText.setText(mReadText);

                                  Toast.makeText(MainActivity.this, "已讀取文字", Toast.LENGTH_SHORT).show();

                                  mEdit.setText("");

                                }

                                catch(Exception e)

                                {

                                }

                        }

                });

        }

}

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以上就是建立文字檔案路徑並寫入文字字串與讀取文件應用的範例，大家可以試試看！

如有任何問題都可以和小黑人一起交流討論喔~謝謝大家~！


☆小黑人☆