Android--向SD卡读写数据

// 向SD卡写入数据  
    private void writeSDcard(String str) {  
        try {  
            // 判断是否存在SD卡  
            if (Environment.getExternalStorageState().equals(  
                    Environment.MEDIA_MOUNTED)) {  
                // 获取SD卡的目录  
                File sdDire = Environment.getExternalStorageDirectory();  
                FileOutputStream outFileStream = new FileOutputStream(  
                        sdDire.getCanonicalPath() + "/test.txt");  
                outFileStream.write(str.getBytes());  
                outFileStream.close();  
                Toast.makeText(this, "数据保存到text.txt文件了", Toast.LENGTH_LONG)  
                        .show();  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
  
      
    // 从SD卡中读取数据  
    private void readSDcard() {  
        StringBuffer strsBuffer = new StringBuffer();  
        try {  
            // 判断是否存在SD  
            if (Environment.getExternalStorageState().equals(  
                    Environment.MEDIA_MOUNTED)) {  
                File file = new File(Environment.getExternalStorageDirectory()  
                        .getCanonicalPath() + "/test.txt");  
                // 判断是否存在该文件  
                if (file.exists()) {  
                    // 打开文件输入流  
                    FileInputStream fileR = new FileInputStream(file);  
                    BufferedReader reads = new BufferedReader(  
                            new InputStreamReader(fileR));  
                    String st = null;  
                    while ((st = reads.readLine()) != null) {  
                        strsBuffer.append(st);  
                    }  
                    fileR.close();  
                } else {  
                    Toast.makeText(this, "该目录下文件不存在", Toast.LENGTH_LONG).show();  
                }  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        Toast.makeText(this, "读取到的数据是：" + strsBuffer.toString() + "",  
                Toast.LENGTH_LONG).show();  
    }  
}