android中将内存中的数据以xml的文件格式写到sdcard中

List<SMSInfo> smsInfos = service.getSMSInof();
try {
File file = new File("/sdcard/smsbackup.xml");

XmlSerializer serializer = Xml.newSerializer();
FileOutputStream fos = new FileOutputStream(file);
serializer.setOutput(fos, "UTF-8");
serializer.startDocument("UTF-8", true);
serializer.startTag(null, "smss");

serializer.startTag(null, "count");
serializer.text(smsInfos.size()+"");
serializer.endTag(null, "count");

for (SMSInfo smsInfo : smsInfos) {
serializer.startTag(null, "sms");

serializer.startTag(null, "id");
serializer.text(smsInfo.getId());
serializer.endTag(null, "id");

serializer.startTag(null, "address");
serializer.text(smsInfo.getAddress());
serializer.endTag(null, "address");

serializer.startTag(null, "date");
serializer.text(smsInfo.getDate());
serializer.endTag(null, "date");

serializer.startTag(null, "type");
serializer.text(smsInfo.getType()+"");
serializer.endTag(null, "type");

serializer.startTag(null, "body");
serializer.text(smsInfo.getBody());
serializer.endTag(null, "body");

serializer.endTag(null, "sms");
}
serializer.endTag(null, "smss");
serializer.endDocument();
fos.flush();
fos.close();
Looper.prepare();
Toast.makeText(getApplicationContext(), "备份完成", 1).show();
Looper.loop();

} catch (Exception e) {
e.printStackTrace();
Looper.prepare();
Toast.makeText(getApplicationContext(), "备份失败", 1).show();
Looper.loop();
}