关于Android“外部存储用户信息”代码注释，请问有知道的吗？

Question

public void onClick(View v) {File sdPath = Environment.getExternalStorageDirectory();File f = new File(sdPath, "data.txt");switch (v.getId()) {case R.id.btn_save:FileOutputStream fos;String saveinfo = et_info.getText().toString();try {fos = new FileOutputStream(f);fos.write(saveinfo.getBytes());fos.close();} catch (Exception e) {e.printStackTrace();}Toast.makeText(MainActivity.this, "数据保存成功", 0).show();break;case R.id.btn_read:String content = "";try {FileInputStream fis = new FileInputStream(f);byte[] buffer = new byte[fis.available()];fis.read(buffer);content = new String(buffer);fis.close();// BufferedReader br = new BufferedReader(new InputStream(fis)));// br.readLine();} catch (Exception e) {e.printStackTrace();}Toast.makeText(MainActivity.this, "保存的数据是：" + content, 0).show();break;default:break;}}

Answer 1

public void onClick(View v) {
//获取产生点击事件的View的ID
switch (v.getId()) {
case R.id.btn_save://当ID为保存按钮的ID
//获取EditText中的内容（去除空格）
String saveinfo = et_info.getText().toString().trim();
FileOutputStream fos;
try {
//将内容写入data.txt中，模式是写在原内容尾处。
fos = openFileOutput("data.txt", Context.MODE_APPEND);
//saveinfo 转化为字节流并通过fos写入对应文件中
fos.write(saveinfo.getBytes());
fos.close();//关流
} catch (Exception e) {
e.printStackTrace();
}
//在屏幕上产生Toast
Toast.makeText(MainActivity.this, "数据保存成功", 0).show();
break;
case R.id.btn_read://当ID为读按钮的ID时
String content = "";//初始化content
try {
//创建文件读取流
FileInputStream fis = openFileInput("data.txt");
byte[] buffer = new byte[fis.available()];//新建byte数组，并设置大小。
fis.read(buffer);//通过流写入数组
content = new String(buffer);//给content初始化赋值
} catch (Exception e) {
e.printStackTrace();
}
Toast.makeText(MainActivity.this, "保存的数据是：" + content, 0)
.show();
break;
default://以后ID都不是时，不采取操作。
break;
}
}