一、File

File类的使用基本和java一致
关于安卓中的一些路径和文件创建
以下实力码代码

File file=new File(getFilesDir(),"test.txt");
  Log.i("info","文件夹路径："+getFilesDir().getAbsolutePath());
  Log.i("info","文件路径："+file.getAbsolutePath());
  if(!file.exists()){
      try {
          Log.i("info","文件创建成功");
          file.createNewFile();
      } catch (IOException e) {
          e.printStackTrace();
      }
  }else{
      Log.i("info","文件创建失败");
      Toast.makeText(MainActivity.this, "文件已存在", Toast.LENGTH_SHORT).show();
  }
  file.delete();//文件删除
  File file = this.getFilesDir();//内部文件夹
  Log.i("info",file.toString());
  File file = this.getCacheDir();//内部临时文件夹
  Log.i("info",file.toString());
  File file = this.getExternalFilesDir("1.txt");//外部文件
  Log.i("info",file.toString());
  File file = this.getExternalCacheDir();//外部临时文件夹
  Log.i("info",file.toString());
  File file = this.getDir("geekband",MODE_PRIVATE);//自定义内部文件夹
  Log.i("info",file.toString());

File的读取

继续实力码代码
此为一个可存储和读取EditText中文字显示在TextView的案例

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    editText = (EditText) findViewById(R.id.main_et);
    button = (Button) findViewById(R.id.main_button);
    textView = (TextView) findViewById(R.id.main_tx);
    
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            writeContent(editText.getText().toString());
            textView.setText(readContent());
        }
    });
}

//写内容
public void writeContent(String content){
    try {
        FileOutputStream fos = openFileOutput("a.txt",MODE_PRIVATE);
        fos.write(content.getBytes());
        fos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

//读内容
public String readContent(){
    String content = null;
    FileInputStream fis = null;
    try {
        fis = openFileInput("a.txt");
        byte[] buffer = new byte[1024];
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int len = 0;
        if((len=fis.read(buffer))!=-1){//读取一个buffer的长度  while if 都行？   他是一次读完的
            Log.i("info","len:"+len);
            baos.write(buffer,0,len);//写入buffer中数据的相同长度
        }
        content = baos.toString();
        fis.close();
        baos.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return content;
}