安卓教程----手把手教你做一个河北空气质量客户端

	public static String HttpGet(String url) throws ClientProtocolException, IOException {
		//新建一个默认的连接
		DefaultHttpClient client = new DefaultHttpClient();
		//新建一个Get方法
		HttpGet get = new HttpGet(url);
		//得到网络的回应
		HttpResponse response = client.execute(get);
		//获得的网页源代码（xml）
		String content = null;

		//如果服务器响应的是OK的话！
		if (response.getStatusLine().getStatusCode() == 200) {
			//以下是把网络数据分段读取下来的过程
			InputStream in = response.getEntity().getContent();
			byte[] data = new byte[1024];
			int length = 0;
			ByteArrayOutputStream bout = new ByteArrayOutputStream();
			while ((length = in.read(data)) != -1) {
				bout.write(data, 0, length);
			}
			//最后把字节流转为字符串 转换的编码为utf-8.
			content = new String(bout.toByteArray(), "utf-8");
		}
		//返回得到的字符串 也就是网页源代码
		return content;
	}

	class GetSource extends AsyncTask<String, Void, String>{
		
		//此函数用来处理后台的事物
		@Override
		protected String doInBackground(String... params) {
			try {
				//这里调用了我们刚才写的下载函数
				return Util.HttpGet("http://121.28.49.85:8080/datas/hour/130000.xml");
			} catch (IOException e) {}
			return null;
		}
		
		//后台事物完成后，此函数用来更改界面的内容
		@Override
		protected void onPostExecute(String result) {
			//让Log输出运行时的记录
			Log.i("test",result);
		}
		
	}

new GetSource().execute();

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

        <LinearLayout
            android:id="@+id/ll"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/tv_time"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_margin="5dp"
                android:background="#7a7"
                android:padding="5dp"
                android:textColor="#eee"
                android:textSize="20sp"
                android:textStyle="bold" />

            <GridView
                android:id="@+id/gv"
                android:layout_width="match_parent"
                android:layout_height="fill_parent"
                android:layout_margin="5dp"
                android:horizontalSpacing="3dp"
                android:verticalSpacing="3dp"
                android:numColumns="3" >
            </GridView>
        </LinearLayout>

        <ProgressBar
            android:id="@+id/pb1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:visibility="visible"
            android:layout_centerVertical="true" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/bg"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="8dp"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tv_city"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="石家庄"
        android:textColor="#4bd"
        android:textSize="20sp"
        android:textStyle="bold" />

    <TextView
        android:id="@+id/tv_aqi"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="223"
        android:textColor="#4bd"
        android:textSize="18sp"
        android:textStyle="bold" />

</LinearLayout>

4、数据分析

		@Override
		protected void onPostExecute(String result) {
			//建立一个解析器
			DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
			DocumentBuilder builder;
			try {
				builder = factory.newDocumentBuilder();
				InputStream is = new ByteArrayInputStream(result.getBytes());
				Document document = builder.parse(is);
				Element element = document.getDocumentElement();
				//获得所有的Citys节点数据
				NodeList cityList = element.getElementsByTagName("Citys");
				
				//获得mapstitle数据，并分解为两部分
				NodeList title = element.getElementsByTagName("MapsTitle");
				String text1 = title.item(0).getTextContent();
				String t[] = text1.split("\\(");
				text1 = t[0];
				t = t[1].split(",");
				tv_time.setText(text1+ "\n" +t[0]);
				
				Element citys = (Element)cityList.item(0);
				NodeList city = citys.getChildNodes();
				
				for (int i=0;i < city.getLength();i++){
					//此时的city节点的item上，有的是一个城市的所有数据
					Node node = city.item(i);
					if (node.getNodeName().equalsIgnoreCase("city")) { //这是一个有效的节点
						CityData cd = new CityData(node);
						nodeList.add(node);
						cdList.add(cd);
					}
				}
			} catch (Exception e) {}

public class CityData implements Serializable{
	
	/**
	 * 继承Serializable是为了在两个不同的界面中进行值的传递
	 */
	private static final long serialVersionUID = -8473485404751986234L;
	//城市类包含了一个城市的数据
	public String name,dataTime,aqi,level,maxPoll,color,intro,tips;
	public List<Pointer> pointerList;

	public CityData(Node cityNode) {
		super();
		//按标签挨个取出相应标签的内容
		this.name = getByTag(cityNode, "name");
		this.dataTime = getByTag(cityNode, "datatime");
		this.aqi = getByTag(cityNode, "aqi");
		this.level = getByTag(cityNode, "level");
		this.maxPoll = getByTag(cityNode, "maxpoll");
		String tmp = getByTag(cityNode, "color");
		this.color = tmp.replace("0x", "#");
		this.intro = getByTag(cityNode, "intro");
		this.tips = getByTag(cityNode, "tips");
		
		Element city = (Element)cityNode;
		NodeList pointers = city.getElementsByTagName("Pointer");
		
		//向city的pointer列表中添加监测点
		pointerList = new ArrayList<Pointer>();
		for (int i=0;i<pointers.getLength();i++){
			Node pNode = pointers.item(i);
			pointerList.add(new Pointer(pNode));
		}
	}

	//从XML的node中取出相应标签中内容的function
	private String getByTag(Node node,String tag) {
		for (int i=0;i<node.getChildNodes().getLength();i++){
			if (tag.equalsIgnoreCase(node.getChildNodes().item(i).getNodeName()))
				return node.getChildNodes().item(i).getTextContent();
		}
		return null;
	}
}

	class gvAdapter extends BaseAdapter{

		//Adapter的数据源，根据这个数据来填充网格列表
		List<CityData> cdList;
		
		public gvAdapter(List<CityData> cdList) {
			super();
			this.cdList = cdList;
		}

		//根据数据的多少返回相应的数值
		@Override
		public int getCount() {
			return cdList.size();
		}

		@Override
		public Object getItem(int position) {
			return null;
		}

		@Override
		public long getItemId(int position) {
			return 0;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			//解析之前写好的每个网格的布局
			convertView = MainActivity.this.getLayoutInflater().inflate(R.layout.gv, null);
			//找到布局中的元素，和布局的背景
			TextView tv_city = (TextView)convertView.findViewById(R.id.tv_city);
			TextView tv_aqi = (TextView)convertView.findViewById(R.id.tv_aqi);
			View bg = convertView.findViewById(R.id.bg);
			//根据数据填充每个格子的内容和背景色
			tv_city.setText(cdList.get(position).name);
			tv_aqi.setText(cdList.get(position).aqi);
			bg.setBackgroundColor(Color.parseColor(cdList.get(position).color));
			return convertView;
		}
		
	}

gv.setOnItemClickListener(new OnItemClickListener() {

	@Override
	public void onItemClick(AdapterView<?> parent, View view,int position, long id) {                                   
                //从当前的界面跳转到城市详细信息界面
		Intent it = new Intent(MainActivity.this, CityActivity.class);
                //对象本身无法使用Intent传递，但是我们继承了Serializable，使传递成为了可能
		it.putExtra("node", cdList.get(position));
		startActivity(it);
	}
			});

<resources>
    <string name="app_name">河北空气质量</string>
    <string name="title_activity_city">城市数据</string>
</resources>