Question

在我的应用程序中，我正在尝试编写一个文件，然后我可以在内部阅读。

有人会举例说明如何将文件写入app的安装文件夹吗？

Answer 1

使用以下代码从Edittext写入文件并从文件读取到Edittext 将以下权限设置为AndroidManifest.xml

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

JAVA CODE

 EditText LoadedText;
    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_main);
            LoadedText=(EditText) findViewById(R.id.LoadedText);
            File sdcard = Environment.getExternalStorageDirectory();

            //Get the text file
            File file = new File("/sdcard/RouterSetup.txt");

            //Read text from file
            StringBuilder text = new StringBuilder();

            try {
                BufferedReader br = new BufferedReader(new FileReader(file));
                String line;

                while ((line = br.readLine()) != null) {
                    text.append(line);
                    text.append('\n');
                }
                br.close();
            }
            catch (IOException e) {
                //You'll need to add proper error handling here
            }
LoadedText.setText(text.toString());
        }

     public void saveFile() {
             try {

                 File  myFile = new File("/sdcard/RouterSetup.txt");
                    myFile.createNewFile();
                FileOutputStream fOut = new FileOutputStream(myFile);
                OutputStreamWriter myOutWriter = 
                                        new OutputStreamWriter(fOut);
                myOutWriter.append(LoadedText.getText());
                myOutWriter.close();
                fOut.close();
                Toast.makeText(getBaseContext(),
                        "Done writing SD " + LoadedText.getText() + ".txt",
                        Toast.LENGTH_SHORT).show();
            } catch (Exception e) {
                Toast.makeText(getBaseContext(), e.getMessage(),
                        Toast.LENGTH_SHORT).show();
            }
            }

getFilesDir（）vs Environment.getDataDirectory（） 公共文件getFilesDir（）

返回文件系统上存储用openFileOutput(String, int)创建的文件的目录的绝对路径。

public static File getExternalStorageDirectory（）

返回主外部存储目录。如果用户已在其计算机上安装此目录，已从设备中删除或发生其他一些问题，则该目录当前可能无法访问。您可以使用getExternalStorageState()确定其当前状态。

如果您想要使用getFilesDir()获取应用程序路径，则会为您提供路径/data/data/your package/files

您可以使用

使用数据/包的Environment var获取路径

getExternalFilesDir(Environment.getDataDirectory().getAbsolutePath()).getAbsolutePath();将返回外部存储根目录中的路径/storage/sdcard/Android/data/your pacakge/files/data

要访问外部资源，您必须在清单中提供WRITE_EXTERNAL_STORAGE和READ_EXTERNAL_STORAGE的权限。

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

Answer 2

最简单的解决方案是

String filename = "stuff.xml";

<强> READ

FileInputStream stream = ctx.openFileInput(filename);

（以下是解析该文件的一个非常简单的例子）

BufferedReader buffReader = new BufferedReader(new InputStreamReader(inputStream)); 
String line;
try {
    while ((line = buffReader.readLine()) != null) {
        ...
        // do something cool
        ...
    }
} catch (IOException e) {
    Log.e("MyApp", "SCREAAAAAM", e);
}

<强> WRITE

OutputStreamWriter outputStreamWriter = new OutputStreamWriter( ctx.openFileOutput(filename, Context.MODE_PRIVATE) );
outputStreamWriter.write("this is text not xml :(");

因此，需要注意的两个主要事项是openFileInput的{{1}}和openFileOutput方法（即您的活动），它们负责繁重的工作

Answer 3

您在谈论哪种类型的文件？对于数据存储，您可以使用shared preferences。对于媒体类型，您可以使用media storage。

Answer 4

    //here i am downloading file from server and writing

    String download_link = "some server location"; 
                URL url = new URL(download_link);
                 HttpsURLConnection c = null;
                if (url.getProtocol().toLowerCase().equals("https")) {
                     trustAllHosts();
                     c = (HttpsURLConnection) url.openConnection();
                     c.setHostnameVerifier(DO_NOT_VERIFY);
                }
                c.setRequestMethod("GET");
                c.setDoOutput(true);
                c.connect();
                String PATH = Environment.getExternalStorageDirectory() + "/download/";
                File file = new File(PATH);
                file.mkdirs();
                File outputFile = new File(file, "Mobi.apk");
                if(outputFile.exists()){
                    outputFile.delete();
                }
                FileOutputStream fos = new FileOutputStream(outputFile);
                InputStream is = c.getInputStream();
                byte[] buffer = new byte[1024];
                int len1 = 0;
                while ((len1 = is.read(buffer)) != -1) {
                    fos.write(buffer, 0, len1);
                }
                fos.close();
                is.close();

you need to add permission in manifest file:    

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

在内部编写文件

4 个答案: