private String body;private String number;private int type;private long id;

public static void backUpXml(File file, List<XmlInfo> smsInfos) throws Exception    {        //xml文件的序列号器  帮助生成一个xml文件        FileOutputStream fos = new FileOutputStream(file);        //获取到xml的序列号        XmlSerializer serializer = Xml.newSerializer();        //序列化初始化        serializer.setOutput(fos, "utf-8");        //创建xml        serializer.startDocument("utf-8", true);        serializer.startTag(null, "smss");                for(XmlInfo info : smsInfos)        {            serializer.startTag(null, "sms");            serializer.attribute(null, "id", String.valueOf(info.getId()));                        serializer.startTag(null, "body");            serializer.attribute(null, "body", info.getBody());            serializer.endTag(null, "body");                        serializer.startTag(null, "number");            serializer.text(info.getNumber());            serializer.endTag(null, "number");                        serializer.endTag(null, "sms");        }                serializer.endTag(null, "smss");        serializer.endDocument();                fos.flush();        fos.close();        }

List<XmlInfo> xmlinfo = new ArrayList<XmlInfo>();                XmlInfo xml1 = new XmlInfo("aaaa","12345678912",1,1);        XmlInfo xml2 = new XmlInfo("bbbb","21987654321",1,2);        XmlInfo xml3 = new XmlInfo("cccc","12345678912",1,3);                xmlinfo.add(xml1);        xmlinfo.add(xml2);        xmlinfo.add(xml3);                        File file = new File(Environment.getExternalStorageDirectory(),"back.xml");        //File file = new File(MainActivity.this.getFilesDir(),"back.xml");        try {            XmlManager.backUpXml(file, xmlinfo);            Toast.makeText(this, "备份成功", 0).show();        } catch (Exception e) {            // TODO 自动生成的 catch 块            e.printStackTrace();            Toast.makeText(this, "备份失败", 0).show();        }