<uses-sdk
  android:minSdkVersion="17"
  android:targetSdkVersion="17" />

 <!-- 往sdcard中寫入數(shù)據(jù)的權(quán)限 -->
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 <!-- 在sdcard中創(chuàng)建/刪除文件的權(quán)限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  for (int i = 0; i < 100; i++) {
   FileSaveUtil.writeFile("Temperature01.txt", String.format("Temperature : %.1f 攝氏度" , 30 + (float) i % 10));
  }
 }

}

package com.wu.sufadi;

import java.io.File;
import java.io.RandomAccessFile;

import android.os.Environment;

public class FileSaveUtil {

 public final static String FILE_PATH = Environment.getExternalStorageDirectory() + "/PhoneData/";

 public static void writeFile(String fileName, String content) {
  String strContent = content + "\n";
  try {
   File fileDir = new File(FILE_PATH);
   if (!fileDir.exists()) {
    fileDir.mkdirs();
    if (!fileDir.exists()) {
     return;
    }
   }
   File file = new File(FILE_PATH, fileName);
   RandomAccessFile raf = new RandomAccessFile(file, "rw");
   raf.seek(file.length());
   raf.write(strContent.getBytes());
   raf.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

 public static void delLogFile(String path) {
  File file = new File(path);
  if (file.exists()) {
   file.delete();
  }
 }
}