android写入文件读取文件

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

<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="net.bwie.localdata.activity.FileActivity">    <Button        android:id="@+id/read_file_btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="读取文件"/>    <Button        android:id="@+id/write_file_btn"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="写入文件"/>    <TextView        android:id="@+id/result_tv"        android:text="结果"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/></LinearLayout>
public class FileActivity extends AppCompatActivity implements View.OnClickListener {    protected Button mReadFileBtn;    protected Button mWriteFileBtn;    protected TextView mResultTv;    public static void startActivity(Context context) {        context.startActivity(new Intent(context, FileActivity.class));    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        super.setContentView(R.layout.activity_file);        initView();    }    @Override    public void onClick(View view) {        if (view.getId() == R.id.read_file_btn) {            String result = readFile();            mResultTv.setText(result);        } else if (view.getId() == R.id.write_file_btn) {            writeFile();        }    }    // 读取文件    private String readFile() {        String filePath = Environment.getExternalStorageDirectory().getPath() + "/abc/";        String fileName = "xyz.txt";        File file = new File(filePath, fileName);        BufferedReader br = null;        try {            br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));            String result = "";            String line = "";            while ((line = br.readLine()) != null) {                result += line;            }            return result;        } catch (Exception e) {            e.printStackTrace();        } finally {            if (br != null) {                try {                    br.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        return null;    }    // 写入文件    private void writeFile() {        // 外部存储私有路径：Android文件夹//        String privatePath = getExternalFilesDir(null).getPath();// 私有路径不分类为null//        String filePath = privatePath + "/abc/";        // 外部存储公共路径：DICM，DOWNLOAD，MUSIC等系统提供的文件夹//        String publicPath = Environment//                .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)//                .getPath();//        String filePath = publicPath + "/abc/";        // 自定义文件路径        String rootPath = Environment.getExternalStorageDirectory().getPath();// 外部存储路径（根目录）        String filePath = rootPath + "/abc/";        String fileName = "xyz.txt";        File file = new File(filePath, fileName);        FileOutputStream fos = null;        try {            fos = new FileOutputStream(file);            fos.write("asdasdas".getBytes());            Toast.makeText(this, "成功", Toast.LENGTH_SHORT).show();        } catch (Exception e) {            e.printStackTrace();            Log.d("1507", "error: " + e.getMessage());        } finally {            if (fos != null) {                try {                    fos.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }    private void initView() {        mReadFileBtn = (Button) findViewById(R.id.read_file_btn);        mReadFileBtn.setOnClickListener(FileActivity.this);        mWriteFileBtn = (Button) findViewById(R.id.write_file_btn);        mWriteFileBtn.setOnClickListener(FileActivity.this);        mResultTv = (TextView) findViewById(R.id.result_tv);    }}

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