【Android】文件存取

最新推荐文章于 2020-03-21 10:09:21 发布

酥脆

最新推荐文章于 2020-03-21 10:09:21 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/BHRSFURGS/article/details/77884528

本文介绍了一个简单的Android应用中如何实现数据的持久化存储。通过使用文件流操作，应用程序可以在设备上保存和加载数据，即使在应用关闭后也能保留这些信息。文章详细展示了如何创建一个能够在启动时加载上次输入文本并在应用销毁前保存当前文本到本地文件的示例。

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保存代码


public class MainActivity extends AppCompatActivity {

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

        editText= (EditText) findViewById(R.id.edit_text);
        String string=load();
        if (!TextUtils.isEmpty(string)){
            editText.setText(string);
            editText.setSelection(string.length());
        }

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        save(editText.getText().toString());
    }

    private void save(String string){

        FileOutputStream mFileOutputStream;
        BufferedWriter mBufferedWriter=null;
        try{

            mFileOutputStream=openFileOutput("data.txt", Context.MODE_PRIVATE);

            Writer mWriter=new OutputStreamWriter(mFileOutputStream);
            mBufferedWriter=new BufferedWriter(mWriter);
            mBufferedWriter.write(string);


        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                if (mBufferedWriter!=null)
                    mBufferedWriter.close();

            } catch (IOException e) {
                e.printStackTrace();
            }

        }

    }
    private String load(){
        FileInputStream mFileInputStream;
        BufferedReader mBufferedReader=null;
        StringBuilder mStringBuilder=new StringBuilder();

        try {
            mFileInputStream=openFileInput("data.txt");
            mBufferedReader=new BufferedReader(new InputStreamReader(mFileInputStream));

            //注意这里的代码控制
            String line;
            while ( ( line=mBufferedReader.readLine() ) !=null){
                mStringBuilder.append(line);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (mBufferedReader != null) {
                try {
                    mBufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        return mStringBuilder.toString();
    }
}