1，建立自己的标签库tld文件
topdt-tags.tld：
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd">
<display-name>topdt</display-name>
<tlib-version>1.0</tlib-version>
<short-name>td</short-name>
<tag>
<name>page</name>
<tag-class>com.topdt.frame.web.tags.PageTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>template</name>
<required>true</required>
</attribute>
</tag>
<tag>
<name>ss</name>
<tag-class>com.topdt.frame.web.tags.SubStringTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>start</name>//这里添加标配的属性
<required>false</required>
<rtexprvalue>false</rtexprvalue>
</attribute>
<attribute>
<name>end</name>
<required>false</required>
<rtexprvalue>false</rtexprvalue>
</attribute>
</tag>
</taglib>
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2：web.xml文件中加入：
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<jsp-config>
<taglib>
<taglib-uri>/topdt</taglib-uri>
<taglib-location>
/WEB-INF/tlds/topdt-tags.tld
</taglib-location>
</taglib>
</jsp-config>
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3：创建class：
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package com.topdt.frame.web.tags;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
public class SubStringTag extends BodyTagSupport {
private static final long serialVersionUID = 1L;
private int start = 0;//这里对应tld中的属性
private int end = 0;
public int getEnd() {
return end;
}
public void setEnd(int end) {
this.end = end;
}
public int getStart() {
return start;
}
public void setStart(int start) {
this.start = start;
}
public int doEndTag() throws JspException {
try {
JspWriter out = pageContext.getOut();
String b = this.getBodyContent().getString();
b = uToS(b);
if (end < b.length()) {
b = b.substring(start, end)+ "..";
}
out.write(b);
} catch (Exception e) {
throw new JspException(e);
}
return SKIP_BODY; // 不包含主体内容
}
private String uToS(String s) throws Exception {
String[] s3 = s.split(";");
String s1 = "";
if (s3.length > 1) {
for (int i = 0; i < s3.length; i++) {
String[] s2 = s3[i].split("&#");
if (s2.length > 1) {
int v = Integer.parseInt(s2[1], 10);
s1 = s1 + s2[0] + (char) v;
} else {
s1 = s1 + s3[i];
}
}
return s1;
} else {
return s;
}
}
}
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