Android 文件读写的例子

import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import org.apache.http.util.EncodingUtils; 

public class MyLogFile { 
      private static FileOutputStream fout; 
      public MyLogFile() { 
      } 

      public static void createFile(){
           try {
                fout = new FileOutputStream("/mnt/sdcard/zyrPad.txt");
                // fout = openFileOutput("/mnt/sdcard/zyrPad.txt",Mode);
          } catch (FileNotFoundException e) {
                e.printStackTrace(); 
          } 
     } 

     //写在/mnt/sdcard/目录下面的文件 
     public static void writeFileSdcard(String message){ 
           try{ 
                 //FileOutputStream fout = openFileOutput(fileName, MODE_PRIVATE);
                message= message+"
";
                byte [] bytes = message.getBytes(); 
                fout.write(bytes); 
           } catch(Exception e){
                e.printStackTrace();
           }
      }

      //读在/mnt/sdcard/目录下面的文件 
      public String readFileSdcard(String fileName){
            String res="";
            try{ 
                  FileInputStream fin = new FileInputStream(fileName);
                  int length = fin.available(); 
                  byte [] buffer = new byte[length]; 
                  fin.read(buffer); 
                  res = EncodingUtils.getString(buffer, "UTF-8"); 
                  fin.close();
            } catch(Exception e){ 
                  e.printStackTrace();
            }
            return res; 
      } 

      /** * 关闭文件流 */ 
      public static void closeFile(){
            try {
                 fout.close(); 
            } catch (IOException e) {
                 e.printStackTrace(); 
            }
      } 
} 

调用的时候很简单：
MyLogFile.createFile();//创建文件
MyLogFile.writeFileSdcard("------------写文字到文件中----------------");

使用完后，记得关闭：
MyLogFile.closeFile()