标签控制页面1

使用标签控制页面逻辑案例：

1、 防止盗链<c:referer site=”” page=””>

Jsp页面的内容：<c:referer site=”http://localhost”page=”index.jsp”>

Tld文件的描述：<tag>

<name>referer</name>

<tag-class>com.hbsi.web.tag.RefererTag</tag-class>

<body-content>empty</body-content>

<attribute>

<name>site</name>

<required>true</required>

<rtexprvalue>true</rtexprvalue>

</attribute>

<attribute>

<name>page</name>

<required>true</required>

<rtexprvalue>true</rtexprvalue>

</attribute>

</tag>

标签处理器：public class RefererTag extends SimpleTagSupport {

private String site;

private String page;

public void setSite(String site) {

this.site = site;

}

public void setPage(String page) {

this.page = page;

}

@Override

public void doTag() throws JspException, IOException {

// 获取request对象

JspContext jc = this.getJspContext();

PageContext pc = (PageContext) jc;

HttpServletRequest request = (HttpServletRequest) pc.getRequest();

HttpServletResponse response = (HttpServletResponse) pc.getResponse();

String referer = request.getHeader("referer");

if (referer == null || !referer.startsWith("http://localhost")) {

// 跳转到首页

//获取地址的完整路径

if (page.startsWith(request.getContextPath())) {

response.sendRedirect(page);

} else if (page.startsWith("/")) {//获取加/的路径

response.sendRedirect(request.getContextPath() + page);

} else {

//最不完整的路径

response.sendRedirect(request.getContextPath() + "/" + page);

}

// 不运行以下的代码

throw new SkipPageException();

}

}

}

2、条件选择<c:if test=””>

Jsp的页面：<%session.setAttribute("user","蛋蛋");%>

<c:if test="${user!=null}">

该回家了，蛋蛋！

</c:if>

Tld文件的描述：<tag>

<name>if</name>

<tag-class>com.hbsi.web.tag.IfTag</tag-class>

<body-content>scriptless</body-content>

<attribute>

<name>test</name>

<required>true</required>

<rtexprvalue>true</rtexprvalue>

</attribute>

</tag>

标签处理器：public class IfTag extends SimpleTagSupport {

private boolean test;

public void setTest(boolean test) {

this.test = test;

}

@Override

public void doTag() throws JspException, IOException {

if(test){

JspFragment jf=this.getJspBody();

jf.invoke(null);

}

}

}