package com.example.test;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import android.os.Bundle;import android.os.Environment;import android.app.Activity;import android.widget.Toast;public class MainActivity extends Activity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);        //要保存的文件名和文件內容    String fileName = "test.txt";    String content = "This is a test.";        //判斷sdcard是否存在    String state = Environment.getExternalStorageState();    if(state.equals(Environment.MEDIA_MOUNTED)) {     //獲取SDCard目錄     File sdcardPath = Environment.getExternalStorageDirectory();          File file = new File(sdcardPath, fileName);     FileOutputStream fos;  try {  fos = new FileOutputStream(file);  fos.write(content.getBytes());  fos.close();  } catch (FileNotFoundException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();    } else {     Toast.makeText(this, "sdcard不存在獲取不可寫入", Toast.LENGTH_SHORT).show();    }      }}