DispIP类
[code="java"]package macleo;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class DispIP extends TagSupport {
/**
*
*/
private static final long serialVersionUID = 1L;
public int doStartTag() throws JspException
{
String ip = pageContext.getRequest().getRemoteAddr();//问题
try {
pageContext.getOut().write(ip);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return super.doStartTag();
}
}[/code]
我查阅了j2ee的api,有点问题不明白,请教各位达人,请指点一下.
1.TagSupport类的定义如下:
[code="java"]/**
- A base class for defining new tag handlers implementing Tag. *
The TagSupport class is a utility class intended to be used as
- the base class for new tag handlers. The TagSupport class
- implements the Tag and IterationTag interfaces and adds additional
- convenience methods including getter methods for the properties in
- Tag. TagSupport has one static method that is included to
- facilitate coordination among cooperating tags. *
Many tag handlers will extend TagSupport and only redefine a
- few methods. */
public class TagSupport implements IterationTag, Serializabl[/code]
其中有
[code="java"] // protected fields
/**
* The PageContext.
*/
protected PageContext pageContext;[/code]
2.PageContext定义如下,是抽象类
[code="java"] *
- The following methods provide support for forwarding, inclusion
- and error handling:
-
forward(),include(), - and
handlePageException(). */
abstract public class PageContext
extends JspContext[/code]
其中,getRequest()方法未实现是abstract的定义如下:
[code="java"]
/**
* The current value of the request object (a ServletRequest).
*
* @return The ServletRequest for this PageContext
*/
abstract public ServletRequest getRequest();[/code]
3.getRemoteAddr方法定义(亦未实现)在interface的ServletRequest中,定义如下:
[code="java"] /**
* Returns the Internet Protocol (IP) address of the client
* or last proxy that sent the request.
* For HTTP servlets, same as the value of the
* CGI variable REMOTE_ADDR.
*
* @return a String containing the
* IP address of the client that sent the request
*
*/
public String getRemoteAddr();
[/code]
***我的问题是:DispIP类中此句,两方法均为实现,何以能编译通过呢????晕,请指点!感谢!
[code="java"]String ip = pageContext.getRequest().getRemoteAddr();//问题[/code]
