当前页面位置: » 丰搜网 » 文档中心 » 详细内容
java servlet 编程及应用之四
httpservlet 是从genericservlet 继承而来，因此它具有genericservlet 类似的方法和对象，是我们使用servlet编程经常用到的包，它支持http 的post 和 get 等方法。
编程思路：下面的例子，运行结果是输出简单地返回客户发送给服务器的请求行和头部信息，以及一些可访问的http 信息等。
snoopservlet.java 的源代码如下：
import java.io.ioexception;
import java.io.printwriter;
import java.util.enumeration;
import javax.servlet.*;
import javax.servlet.http.*;
public class snoopservlet extends httpservlet {
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception
{
printwriter out = response.getwriter();
response.setcontenttype("text/plain");
out.println("snoop servlet");
out.println();
out.println("servlet init parameters:");
enumeration e = getinitparameternames();
while (e.hasmoreelements()) {
string key = (string)e.nextelement();
string value = getinitparameter(key);
out.println(" " + key + " = " + value);
}
out.println();
out.println("context init parameters:");
servletcontext context = getservletcontext();
enumeration enum = context.getinitparameternames();
while (enum.hasmoreelements()) {
string key = (string)enum.nextelement();
object value = context.getinitparameter(key);
out.println(" " + key + " = " + value);
}
out.println();
out.println("context attributes:");
enum = context.getattributenames();
while (enum.hasmoreelements()) {
string key = (string)enum.nextelement();
object value = context.getattribute(key);
out.println(" " + key + " = " + value);
}
out.println();
out.println("request attributes:");
e = request.getattributenames();
while (e.hasmoreelements()) {
string key = (string)e.nextelement();
object value = request.getattribute(key);
out.println(" " + key + " = " + value);
}
out.println();
out.println("servlet name: " + getservletname());
out.println("protocol: " + request.getprotocol());
out.println("scheme: " + request.getscheme());
out.println("server name: " + request.getservername());
out.println("server port: " + request.getserverport());
out.println("server info: " + context.getserverinfo());
out.println("remote addr: " + request.getremoteaddr());
out.println("remote host: " + request.getremotehost());
out.println("character encoding: " + request.getcharacterencoding());
out.println("content length: " + request.getcontentlength());
out.println("content type: "+ request.getcontenttype());
out.println("locale: "+ request.getlocale());
out.println("default response buffer: "+ response.getbuffersize());
out.println();
out.println("parameter names in this request:");
e = request.getparameternames();
while (e.hasmoreelements()) {
string key = (string)e.nextelement();
string[] values = request.getparametervalues(key);
out.print(" " + key + " = ");
for(int i = 0; i < values.length; i++) {
out.print(values[i] + " ");
}
out.println();
}
out.println();
out.println("headers in this request:");
e = request.getheadernames();
while (e.hasmoreelements()) {
string key = (string)e.nextelement();
string value = request.getheader(key);
out.println(" " + key + ": " + value);
}
out.println();
out.println("cookies in this request:");
cookie[] cookies = request.getcookies();
if (cookies != null) {
for (int i = 0; i < cookies.length; i++) {
cookie cookie = cookies[i];
out.println(" " + cookie.getname() + " = "+ cookie.getvalue());
}
}
out.println();
out.println("request is secure: " + request.issecure());
out.println("auth type: " + request.getauthtype());
out.println("http method: " + request.getmethod());
out.println("remote user: " + request.getremoteuser());
out.println("request uri: " + request.getrequesturi());
out.println("context path: " + request.getcontextpath());
out.println("servlet path: " + request.getservletpath());
out.println("path info: " + request.getpathinfo());
out.println("path trans: " + request.getpathtranslated());
out.println("query string: " + request.getquerystring());
out.println();
httpsession session = request.getsession();
out.println("requested session id: " +
request.getrequestedsessionid());
out.println("current session id: " + session.getid());
out.println("session created time: " + session.getcreationtime());
out.println("session last accessed time: " +session.getlastaccessedtime());
out.println("session max inactive interval seconds: " + session.getmaxinactiveinterval());
out.println();
out.println("session values: ");
enumeration names = session.getattributenames();
while (names.hasmoreelements()) {
string name = (string) names.nextelement();
out.println(" " + name + " = " + session.getattribute(name));
}
}
}
编程技巧说明：
程序输出init parameters(初始化参数)、attribute names in this request、parameter names in this request、headers in this request、cookies in this request 和 session information等信息。
方法getrequesturi返回的对象uri 是作为url 的一部分，是去掉url 中用于指定机器的那部分；方法getpathinfo 返回的字符串是客户向servlet 传送的各种选项，这些选项是跟在servlet 的url 之后的，方法getpathtranslated 返回的字符串是servlet 的自己的绝对路径名，snoopservlet.class 文件位置是c:\jswdk-1.0.1\examples\web-inf\servlets\snoopservlet.class，则方法getpathtranslated 返回的字符串值就是它。
在浏览器中输入如下的地址：
http://localhost:8080/examples/servlet/snoopservlet
则会输出结果。
