今天学习了一个分页小技术，自定义标签完成分页，分页样式和百度类似，觉得很有必要记录下来。样式如下图
首先此技术是自定义jsp标签。
commons.tld中内容如下
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE taglib
PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
"http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
<tlib-version>2.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>arley</short-name>
<uri>http://arley.cn/common/</uri>
<display-name>Common Tag</display-name>
<description>Common Tag library</description>
<tag>
<name>page</name>
<tag-class>com.itheima.crm.common.NavigationTag</tag-class>
<body-content>JSP</body-content>
<description>create navigation for paging</description>
<attribute>
<name>bean</name>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>number</name>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>url</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>
import java.io.IOException;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
import org.apache.taglibs.standard.tag.common.core.UrlSupport;
/**
* 显示格式 上一页 1 2 3 4 5 6 7 8 9 10下一页
*/
public class NavigationTag extends TagSupport {
static final long serialVersionUID = 2372405317744358833L;
/**
* request 中用于保存Page<E> 对象的变量名,默认为“page”
*/
private String bean = "page";
/**
* 分页跳转的url地址,此属性必须
*/
private String url = null;
/**
* 显示页码数量
*/
private int number = 10;
@Override
public int doStartTag() throws JspException {
JspWriter writer = pageContext.getOut();
HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
Page page = (Page)request.getAttribute(bean);
if (page == null)
return SKIP_BODY;
url = resolveUrl(url, pageContext);
try {
//计算总页数
int pageCount = page.getTotal() / page.getSize();
if (page.getTotal() % page.getSize() > 0) {
pageCount++;
}
writer.print("<nav><ul class=\"pagination\">");
//显示“上一页”按钮
if (page.getPage() > 1) {
String preUrl = append(url, "page", page.getPage() - 1);
preUrl = append(preUrl, "rows", page.getSize());
writer.print("<li><a href=\"" + preUrl + "\">上一页</a></li>");
} else {
writer.print("<li class=\"disabled\"><a href=\"#\">上一页</a></li>");
}
//显示当前页码的前5页码和后4页码 1 2 3 4 5 6 7 8 9 10
//若1 则 1 2 3 4 5 6 7 8 9 10,
//若5 则 1 2 3 4 5 6 7 8 9 10,若10 则 5 6 7 8 9 10 11 12 13 14
int indexPage = (page.getPage() - 5 > 0)? page.getPage() - 5 : 1;
for(int i=1; i <= number && indexPage <= pageCount; indexPage++, i++) {
if(indexPage == page.getPage()) {
writer.print( "<li class=\"active\"><a href=\"#\">"+indexPage+"<span class=\"sr-only\">(current)</span></a></li>");
continue;
}
String pageUrl = append(url, "page", indexPage);
pageUrl = append(pageUrl, "rows", page.getSize());
writer.print("<li><a href=\"" + pageUrl + "\">"+ indexPage +"</a></li>");
}
//显示“下一页”按钮
if (page.getPage() < pageCount) {
String nextUrl = append(url, "page", page.getPage() + 1);
nextUrl = append(nextUrl, "rows", page.getSize());
writer.print("<li><a href=\"" + nextUrl + "\">下一页</a></li>");
} else {
writer.print("<li class=\"disabled\"><a href=\"#\">下一页</a></li>");
}
writer.print("</nav>");
} catch (IOException e) {
e.printStackTrace();
}
return SKIP_BODY;
}
private String append(String url, String key, int value) {
return append(url, key, String.valueOf(value));
}
/**
* 为url 参加参数对儿
*
* @param url
* @param key
* @param value
* @return
*/
private String append(String url, String key, String value) {
if (url == null || url.trim().length() == 0) {
return "";
}
if (url.indexOf("?") == -1) {
url = url + "?" + key + "=" + value;
} else {
if(url.endsWith("?")) {
url = url + key + "=" + value;
} else {
url = url + "&" + key + "=" + value;
}
}
return url;
}
/**
* 为url 添加翻页请求参数
*
* @param url
* @param pageContext
* @return
* @throws javax.servlet.jsp.JspException
*/
private String resolveUrl(String url, javax.servlet.jsp.PageContext pageContext) throws JspException{
//UrlSupport.resolveUrl(url, context, pageContext)
Map params = pageContext.getRequest().getParameterMap();
for (Object key:params.keySet()) {
if ("page".equals(key) || "rows".equals(key)) continue;
Object value = params.get(key);
if (value == null) continue;
if (value.getClass().isArray()) {
url = append(url, key.toString(), ((String[])value)[0]);
} else if (value instanceof String) {
url = append(url, key.toString(), value.toString());
}
}
return url;
}
/**
* @return the bean
*/
public String getBean() {
return bean;
}
/**
* @param bean the bean to set
*/
public void setBean(String bean) {
this.bean = bean;
}
/**
* @return the url
*/
public String getUrl() {
return url;
}
/**
* @param url the url to set
*/
public void setUrl(String url) {
this.url = url;
}
public void setNumber(int number) {
this.number = number;
}
}
page类必不可少，4属性，当前页，每页显示条数，总记录数，查询数据
import java.util.List;
public class Page<T> {
private int total;
private int page;
private int size;
private List<T> rows;
public int getTotal() {
return total;
}
public void setTotal(int total) {
this.total = total;
}
public int getPage() {
return page;
}
public void setPage(int page) {
this.page = page;
}
public int getSize() {
return size;
}
public void setSize(int size) {
this.size = size;
}
public List<T> getRows() {
return rows;
}
public void setRows(List<T> rows) {
this.rows = rows;
}
}
jsp中引入此标签
<%@ taglib prefix="arley" uri="http://arley.cn/common/" %>
在需要显示分页按钮的地方写入标签、
<arley:page url=""/>
url为必填属性,请求路径,
bean="" 在request中取出的key 默认为page
number="" 每页显示数据条数 默认10条
点击页码会传给后台当前页数,参数name为page,所以要使用page属性接收.
别的基本没什么了,就这么简单,
算是第一条博客把，不是很会写，慢慢学习，希望以后越写越好，记录下来学习的技术。
学习了很多技术，每学习一种都非常开心。不断地丰富自己，逐渐的成长。