xml的生成与解析_老师笔记

使用序列化器生成一个xml文件
 
    //1,初始化一个xml文件的序列化器
            XmlSerializer serializer = Xml.newSerializer();
            //2.初始化序列器参数
            File file = new File(Environment.getExternalStorageDirectory(),"backup.xml");
            FileOutputStream fos = new FileOutputStream(file);
            serializer.setOutput(fos, "UTF-8");
            //3.开始写xml文件.
            serializer.startDocument("UTF-8", true);
            serializer.startTag(null, "smss");
            for(SmsInfo info : smsInfos){
               //开始写sms节点
                serializer.startTag(null, "sms");
                //开始写body节点
                serializer.startTag(null, "body");
                serializer.text(info.getBody());
                //body节点结束
                serializer.endTag(null, "body"); 
 
                //开始写address节点
                serializer.startTag(null, "address");
                serializer.text(info.getAddress());
                serializer.endTag(null, "address");
 
                //开始写data节点
                serializer.startTag(null, "date");
                serializer.text(info.getDate()+"");
                serializer.endTag(null, "date");
                // sms节点结束
                serializer.endTag(null, "sms");
            }
            //smss根节点结束
            serializer.endTag(null, "smss");
            //xml 结束
            serializer.endDocument();
            fos.close();
 
            Toast.makeText(this, "备份短信成功", 0).show();
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "备份短信失败", 0).show();
        }
 
#12.使用pull解析xml格式的数据 (重要)
 
    public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // 设置activity显示的布局
        setContentView(R.layout.activity_main);
        TextView tv_info = (TextView) findViewById(R.id.tv_info);
        StringBuilder sb = new StringBuilder();
        try {
            //获取我们解析出来的天气信息
            List<Channel> channels = WeatherService.getAllWeatherInfos(getClass().getClassLoader().getResourceAsStream("weather.xml"));
            for(Channel channel : channels){
                sb.append(channel.toString());
                sb.append("\n");
            }
            //把解析出来的天气信息设置到textview上
            tv_info.setText(sb.toString());
 
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "解析天气信息失败", 0).show();
        }
 
    }
 
    }
 
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      public class WeatherService {
    /**
     * 解析服务器返回的数据 获取天气信息
     * @param is 服务器返回的包含天气信息的流 (xml)
     * @return
     */
    public static List<Channel> getAllWeatherInfos(InputStream is) throws Exception{
        List<Channel> channels = null;
        Channel channel = null;
        //1.获取xml解析器
        XmlPullParser parser = Xml.newPullParser();
        //2.设置xml解析器的参数
        parser.setInput(is, "utf-8");
        //3.开始解析xml文件.
 
        int type = parser.getEventType();// 获取当前的事件的类型
        while (type!=XmlPullParser.END_DOCUMENT){ //需要让pull解析器解析到文件的末尾
            switch (type) {
            case XmlPullParser.START_TAG:
                if("weather".equals(parser.getName())){//总的开始节点
                    channels = new ArrayList<Channel>(); //初始化集合
                }else if("channel".equals(parser.getName())){//某个城市的信息开始了.
                    channel = new Channel();
                    //获取到id的属性值
                    String id = parser.getAttributeValue(0);
                    channel.setId(Integer.parseInt(id));
                    //解析city节点
                }else if("city".equals(parser.getName())){
                    String city = parser.nextText();
                    channel.setCity(city);
                    //解析温度节点
                }else if("temp".equals(parser.getName())){
                    String temp = parser.nextText();
                    channel.setTemp(temp);
                    //解析风力节点
                }else if("wind".equals(parser.getName())){
                    String wind = parser.nextText();
                    channel.setWind(wind);
                     //解析pm250节点
                }else if("pm250".equals(parser.getName())){
                    String pm250 = parser.nextText();
                    channel.setPm250(Integer.parseInt(pm250));
                }
                break;
            //判断xml的结束节点
            case XmlPullParser.END_TAG:
                if("channel".equals(parser.getName())){
                    //把解析的内容加入到集合中
                    channels.add(channel);
                    channel = null;
                }
                break;
            }
 
            type = parser.next();
        }
 
        is.close();
        return channels;//把所有的频道的集合返回回去
     }
    }