java免费自定义代码 java自定义语言( 三 )


实例制作:
(1)index.jsp
%@ page language="java" pageEncoding="UTF-8"%
%@ taglib uri="/WEB-INF/tagLib.tld" prefix="aaa" %
!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
html:html
head
/head
titleindex.jsp/title
body
aaa:showDataTag pageSize="12"/aaa:showDataTag
br
/body
/html:html
(2)tagLib.tld
?xml version="1.0" encoding="UTF-8"?
!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" ""
taglib
tlibversion1.2/tlibversion
jspversion1.1/jspversion
shortnamebean/shortname
uriMyTagLib/uri
tag
nameshowDataTag/name
tagclassTagSelect/tagclass
attribute
namepageSize/name
requiredtrue/required
/attribute
/tag
/taglib
(3)TagSelect.java
import java.io.IOException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
public class TagSelect extends TagSupport{
private int pageSize;// pageSize属性,控制页面显示的个数,并且要生成get和set方法
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int doStartTag() {
pageContext.getOut();// 获取JSP页面的输出流 out
pageContext.getRequest();// 获取JSP页面的请求对象 request
pageContext.getSession();// 获取JSP页面的会话对象 session
pageContext.getServletContext();// 获取JSP页面的应用对象 application [Page]
JspWriter out = pageContext.getOut();// 用pageContext获取out,他还能获取session等,基本上jsp的内置对象都能获取
System.out.println("out=" + out);
TestNumber t = new TestNumber();
if (t.isNumeric(Integer.toString(pageSize))) {
for (int i = 0; ipageSize; i++) {
try {
out.println("table");
out.println("tr");
out.println("td");
out.println(i);
out.println("/td");
out.println("td");
out.println(i * 10);
out.println("/td");
out.println("/tr");
out.println("/table");
} catch (IOException e) {
e.printStackTrace();
}
}
} else {
try {
out.println("table");
out.println("tr");
out.println("td");
out.println("你输入的参数格式不对");
out.println("/td");
out.println("td");
out.println("/td");
out.println("/tr");
out.println("/table");
} catch (IOException e) {
e.printStackTrace();
}
}
return EVAL_PAGE;// 标签执行完后,继续执行后面的
}
public int doEndTag() {
return SKIP_BODY;// 标签执行完后,不继续执行后面的
}
2.Java中标签的使用
int i = 0;
System.out.println("label1");
label1: for (int k = 0; k5; k++) {
i++;
if (k == 2) {
break label1;
}
System.out.println(i);

输出结果是:
label1
1
2
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