asp.net的实时天气及24小时天气预报(c#) 修改其中的url获得其他城市的天气情况
如广州为：
http://weather.yahoo.com/forecast/chxx0037_c.html
注意仅适用于获得yahoo上的天气预报

getweather.aspx
-----------------------------------

<%@ page language="c#" codebehind="getweather.aspx.cs" autoeventwireup="false" inherits="test.getweather" %>

weather

getweather.aspx.cs
---------------------------------------

using system;
using system.collections;
using system.componentmodel;
using system.data;
using system.drawing;
using system.web;
using system.web.sessionstate;
using system.web.ui;
using system.web.ui.webcontrols;
using system.web.ui.htmlcontrols;
using system.net;
using system.io;

namespace test
{

public class getweather : system.web.ui.page
{
protected system.web.ui.webcontrols.label lblweather;
protected system.web.ui.webcontrols.label weather2;
protected system.web.ui.webcontrols.button btnget2;
protected system.web.ui.webcontrols.button btnget;

private void page_load(object sender, system.eventargs e)
{
// put user code to initialize the page here
}

#region web form designer generated code
override protected void oninit(eventargs e)
{
//
// codegen: this call is required by the asp.net web form designer.
//
initializecomponent();
base.oninit(e);
}

///

}
#endregion

private void btnget_click(object sender, system.eventargs e)
{

webrequest wreq=webrequest.create("http://weather.yahoo.com/forecast/chxx0037_c.html");

httpwebresponse wresp=(httpwebresponse)wreq.getresponse();

string html ="";
stream s=wresp.getresponsestream();

streamreader objreader = new streamreader(s);

string sline = "";
int i = 0;

while (sline!=null)
{
i++;
sline = objreader.readline();
if (sline!=null)
html += sline;
}

string temp= "";
int start,stop;

start = html.indexof("
",0,html.length);

stop = html.indexof("
",0,html.length);

temp = html.substring(start, stop - start);
start = temp.indexof("");
stop = temp.indexof("");

string degree = temp.substring(start+3,stop - start -3);

start = temp.indexof(" stop = temp.indexof("
",start);

string img = temp.substring(start,stop - start);
lblweather.text = degree + "
" + img;

}

private void btnget2_click(object sender, system.eventargs e)
{
webrequest wreq=webrequest.create("http://cn.weather.yahoo.com/chxx/chxx0037/index_c.html");

httpwebresponse wresp=(httpwebresponse)wreq.getresponse();

string html ="";
stream s=wresp.getresponsestream();

streamreader objreader = new streamreader(s,system.text.encoding.getencoding("gb2312"));

temp = html.substring(start, stop - start);
weather2.text = temp;
}
}
}