将应用程序数据保存到文本文件

Question

您好，我在eclipse中创建了一个android应用程序，我希望将应用程序中的数据保存到一个文本文件中，该文件存储在我安装了该应用程序的平板电脑上。 我尝试了几种不同的方法来执行此操作，但到目前为止未成功。 到目前为止，我已经能够保存该应用程序，但是我不确定将其保存到哪里，大多数网站都显示了保存到外部和内部的内容，但是没有解释这些文件保存到的位置，或者我如何检索它们。 有谁知道任何有用的网站会对此有所帮助。 该应用包含三个表单，需要用户输入，然后我希望用户能够保存这些表单，以便他们可以通过电子邮件发送。 这是我的其中一种形式的代码的副本

package com.ifmltd.ifmapp;

public class Checklist extends Activity {

private final static String STORETEXT = "storetext.txt";
private EditText txtEditor;
private TextView txtViewer;
private CheckBox cBoxClick;
private Spinner spinSelect;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.checklist);
    Home();
    Save();

    txtViewer = (TextView) findViewById(R.id.txtTitle);
    txtViewer = (TextView) findViewById(R.id.txtVehicle);
    txtViewer = (TextView) findViewById(R.id.txtInterior);
    txtViewer = (TextView) findViewById(R.id.txtExterior);
    txtViewer = (TextView) findViewById(R.id.txtEngine);
    txtViewer = (TextView) findViewById(R.id.txtOther);
    txtViewer = (TextView) findViewById(R.id.txtDefects);
    txtViewer = (TextView) findViewById(R.id.txtName);
    txtViewer = (TextView) findViewById(R.id.txtDefectInfo);
    txtViewer = (TextView) findViewById(R.id.txtAddCom);
    txtViewer = (TextView) findViewById(R.id.txtFaults);
    txtEditor = (EditText) findViewById(R.id.etxtAddCom);
    txtEditor = (EditText) findViewById(R.id.etxtDefects);
    spinSelect = (Spinner) findViewById(R.id.spinName);
    spinSelect = (Spinner) findViewById(R.id.spinVehicle);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxFLevel);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxWWasher);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxSWheel);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxBrakes);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxClutch);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxHorn);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxHeater);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxWLights);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxMirrors);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxTires);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxExhaust);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxLights);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxExLeaks);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxBody);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxOil);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxCool);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxBelts);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxEnLeaks);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxBolts);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxWTri);
    cBoxClick = (CheckBox) findViewById(R.id.cBoxFire);

}

public void saveClicked(View v) {
    try {
        OutputStreamWriter out = new OutputStreamWriter(openFileOutput(
                STORETEXT, 0));
        out.write(txtEditor.getText().toString());
        out.write(txtViewer.getText().toString());
        out.write(cBoxClick.getText().toString());
        out.write(spinSelect.getSelectedView().toString());
        out.close();

        Toast

        .makeText(this, "Your contents have been saved.", Toast.LENGTH_LONG)
                .show();
    }

    catch (Throwable t) {

        Toast

        .makeText(this, "Error: " + t.toString(), Toast.LENGTH_LONG).show();

    }
}

public void readFileInEditor() {
    try {

        InputStream in = openFileInput(STORETEXT);
        if (in != null) {
            InputStreamReader tmp = new InputStreamReader(in);
            BufferedReader reader = new BufferedReader(tmp);

            String str;
            StringBuilder buf = new StringBuilder();

            while ((str = reader.readLine()) != null) {
                buf.append(str + "n");
            }

            in.close();
            txtEditor.setText(buf.toString());
        }
    }

    catch (java.io.FileNotFoundException e) {
    }

    catch (Throwable t) {
        Toast.makeText(this, "Error: " + t.toString(), Toast.LENGTH_LONG)
                .show();

    }
}

private void Home() {
    Button btnHome = (Button) findViewById(R.id.btnHome);
    btnHome.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View view) {
            startActivity(new Intent(Checklist.this, Index.class));
        }
    });
}

这表明文本正在保存，我只是不知道它将保存到哪里，而我无法访问它

Answer 1

您有两种在Android系统中读写文件的选择，一种是将其存储在内部存储器中（内部存储器中存储的文件只能由其创建的应用程序读取，除非其他文件管理器可以访问它，否则手机是扎根的），第二个是外部存储设备（通常在这里存储图片，音乐，视频等。这可能是您的外部SD卡空间，也可能是电话的外部存储设备）。 我为这两个选项提供了两个不同的代码段。

写入内部存储

String msg = "This message will be written in internal storage."; // this message will be written in the file
try {
        FileOutputStream fileoutputstream = openFileOutput("example.txt",
                Context.MODE_PRIVATE); //here context.MODE_PRIVATE means the file will be stored in internal storage and example.txt is the file you want to create it with the name
        BufferedOutputStream bufferedoutputstream = new BufferedOutputStream(
                fileoutputstream);
        bufferedoutputstream.write(msg.getBytes());
        Toast.makeText(this, "file written", Toast.LENGTH_SHORT).show();
        bufferedoutputstream.close();
    } catch (FileNotFoundException e) {
        Toast.makeText(this, "File not found", Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    } catch (IOException e) {
        Toast.makeText(this, "IOexception", Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }

请记住，这只是使用该技术的简单示例，即使文件存在，也会每次都再次创建文件example.txt。

从内部文件读取

try {
        FileInputStream fileinputstream = openFileInput("example.txt");
        BufferedReader bufferedreader = new BufferedReader(
                new InputStreamReader(fileinputstream));
        String fileContents = bufferedreader.readLine();
        Toast.makeText(this, fileContents, Toast.LENGTH_LONG).show();
    } catch (FileNotFoundException e) {
        Toast.makeText(this, "File not found", Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    } catch (IOException e) {
        Toast.makeText(this, "IOexception", Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }

写入外部存储

String msg = "This file is to be stored in the external storage."; // this message will be written in the file
File externalpath = Environment.getExternalStorageDirectory(); // this line of code gets the external storage directory which usually is sdcard/, extSdcard/ or mnt/
File newfile = new File(externalpath, "example.txt");
//I have just created the file in the base of external storage but you can also create new folder in the external storage and then create the file in it.

    try {
        FileOutputStream fileoutputstream = new FileOutputStream(newfile);
        BufferedWriter bufferedwrite = new BufferedWriter(
                new OutputStreamWriter(fileoutputstream));
        bufferedwrite.write(msg.getBytes());
        Toast.makeText(this, "file written", Toast.LENGTH_SHORT).show();
        bufferedwrite.close();
        fileoutputstream.close();
    } catch (FileNotFoundException e) {
        Toast.makeText(this, "File not found", Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    } catch (IOException e) {
        Toast.makeText(this, "IOexception", Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }

从外部存储读取

File externalpath = Environment.getExternalStorageDirectory();
File newfile = new File(externalpath, "example.txt");
//You need to modify above line appropriately if you have stored the file in some directory or other place.

    FileInputStream fileinputstream;
    try {
        fileinputstream = new FileInputStream(newfile);
        BufferedReader bufferedreader = new BufferedReader(
                new InputStreamReader(fileinputstream));
        String filecontents = bufferedreader.readLine();
        Toast.makeText(this, filecontents, Toast.LENGTH_SHORT).show();
        bufferedreader.close();
        fileinputstream.close();
    } catch (FileNotFoundException e) {
        Toast.makeText(this, "File not found", Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    } catch (IOException e) {
        Toast.makeText(this, "IOexception", Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }

注意：上面提到的代码仅作为示例，它可能不是最有效的方法，因此您可能需要添加更多的逻辑检查和错误处理。

编辑：不要忘记在Manifest.xml文件中添加必要的权限。 在这种情况下，我会添加

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>