web登陆无非就是网页获取，cookie 的管理，post和get方式的模拟。

1.网页内容获取
java.io.inputstream in;
java.net.url url = new java.net.url(www.xyz.com/content.html);
java.net.httpurlconnection connection = (java.net.httpurlconnection)
url.openconnection();
connection = (java.net.httpurlconnection) url.openconnection();
//模拟成ie
connection.setrequestproperty("user-agent","mozilla/4.0 (compatible; msie 6.0; windows 2000)");
connection.connect();
in = connection.getinputstream();
java.io.bufferedreader breader =
new bufferedreader(new inputstreamreader(in , "gbk"));
string str=breader.readline());
while(st != null){
system.out.println(str);
str=breader.readline());
}
2.cookie管理 1.直接的方式
取得cookie：
httpurlconnection huc= (httpurlconnection) url.openconnection();
inputstream is = huc.getinputstream();
// 取得sessionid.
string cookieval = hc.getheaderfield("set-cookie");
string sessionid;
if(cookieval != null)
{
sessionid = cookieval.substring(0, cookieval.indexof(";"));
} 发送设置cookie：
httpurlconnection huc= (httpurlconnection) url.openconnection();
if(sessionid != null)
{
huc.setrequestproperty("cookie", sessionid);
}
inputstream is = huc.getinputstream(); 2.利用的jcookie包(http://jcookie.sourceforge.net/ )
获取cookie:
url url = new url("http://www.site.com/");
httpurlconnection huc = (httpurlconnection) url.openconnection();
huc.connect();
inputstream is = huc.getinputstream();
client client = new client();
cookiejar cj = client.getcookies(huc); 新的请求,利用上面获取的cookie: url = new url("http://www.site.com/");
huc = (httpurlconnection) url.openconnection();
client.setcookies(huc, cj); 3.post方式的模拟
url url = new url("www.xyz.com");
httpurlconnection huc = (httpurlconnection) url.openconnection();
//设置允许output
huc.setdooutput(true);
//设置为post方式
huc.setrequestmethod("post");
huc.setrequestproperty("user-agent","mozilla/4.7 [en] (win98; i)");
stringbuffer sb = new stringbuffer();
sb.append("username="+usernme);
sb.append("&password="+password); //post信息
outputstream os = huc.getoutputstream();
os.write(sb.tostring().getbytes("gbk"));
os.close(); bufferedreader br = new bufferedreader(new inputstreamreader(huc.getinputstream())) huc.connect(); string line = br.readline(); while(line != null){ l system.out.printli(line); line = br.readline(); }