文章目录
自定义jsp分页标签
今天的分页标签是在上一次封装通用分页的基础上继续操作了，没搞懂通用分页可以去看上一次的博客。
思路：
1、首先我要先对pageBean这个类增加属性和封装一些方法：url（我们跳转servlet的全路径名）、paramMap（获取对应的属性和值）、核心方法setRequest()：定义初始化方法，把request当成参数传入，把上一次的请求存入、getMaxPage(获取最大页数)、getNxetPage(获取下一页)、getPreviousPage（获取上一页）
2、然后我们要定义分页标签了，首先写助手类，属性无疑就一个就是我们的pageBean，分页所需全部在里面，然后我们需要在里面把分页所需的html和js代码全部拼接上，并通过我们的pageBean给跳转页面、属性等赋值。
3、最后写好servlet调用通用分页方法，配置好描述文件(tld),引入我们的标签库(taglib)，对标签进行测试
下面就是我的代码了
首先是增强的pageBean
public class PageBean {
private int page = 1;// 页码
private int rows = 10;// 页大小
private int total = 0;// 总记录数
private boolean pagination = true;// 是否分页
private String url;
private Map<String, String[]> paramMap = new HashMap<>();
// 定义初始化方法，存入上一次请求的值
public void setRequest(HttpServletRequest req) {
this.setPage(req.getParameter("page"));
this.setRows(req.getParameter("rows"));
this.setPagination(req.getParameter("pagination"));
// getRequestURL获取到浏览器请求的全路径
this.setUrl(req.getRequestURL().toString());
// getParameterMap可以获取到一次url请求所携带的所有参数
this.setParamMap(req.getParameterMap());
}
public void setPagination(String pagination) {
if (StringUtils.isNotBlank(pagination)) {
this.setPagination(!"false".equals(pagination));
}
}
public void setRows(String rows) {
if (StringUtils.isNotBlank(rows))
this.setRows(Integer.valueOf(rows));
}
public void setPage(String page) {
if (StringUtils.isNotBlank(page)) {
this.setPage(Integer.valueOf(page));
}
}
public PageBean() {
super();
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public Map<String, String[]> getParamMap() {
return paramMap;
}
public void setParamMap(Map<String, String[]> paramMap) {
this.paramMap = paramMap;
}
public int getPage() {
return page;
}
public void setPage(int page) {
this.page = page;
}
public int getRows() {
return rows;
}
public void setRows(int rows) {
this.rows = rows;
}
public int getTotal() {
return total;
}
public void setTotal(int total) {
this.total = total;
}
public void setTotal(String total) {
this.total = Integer.parseInt(total);
}
public boolean isPagination() {
return pagination;
}
public void setPagination(boolean pagination) {
this.pagination = pagination;
}
/**
* 获得起始记录的下标
*
* @return
*/
public int getStartIndex() {
return (this.page - 1) * this.rows;
}
@Override
public String toString() {
return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
}
/**
* 获取到总页数
* @return
*/
public int getMaxPage() {
return this.total % this.rows == 0 ?
this.total / this.rows :
(this.total / this.rows) + 1;
}
/**
* 获取下一页页码
* @return
*/
public int getNextPage() {
return this.page < this.getMaxPage() ? this.page+1 : this.page;
}
/**
* 获取上一页页码
* @return
*/
public int getPreviousPage() {
return this.page > 1 ? this.page-1 : this.page;
}
}
标签助手类：PageTag
public class PageTag extends BodyTagSupport {
private static final long serialVersionUID = -8476740758233598045L;
private PageBean pageBean;
@Override
public int doStartTag() throws JspException {
JspWriter out = pageContext.getOut();
try {
out.write(toHTML());
} catch (IOException e) {
e.printStackTrace();
}
return super.doStartTag();
}
public String toHTML() {
StringBuffer sb=new StringBuffer();
//下一次请求提交到后台的表单html代码拼接
sb.append("<form id='pageBeanForm' action='"+pageBean.getUrl()+"' method='post'>");
Map<String, String[]> paramMap = pageBean.getParamMap();
if(paramMap!=null&¶mMap.size()>0) {
for(Entry<String, String[]> entry:paramMap.entrySet()) {
if(!"page".equals(entry.getKey())) {
for(String val:entry.getValue()) {
sb.append("<input type='hidden' name='"+entry.getKey()+"'> value='"+val+"'");
}
}
}
}
sb.append("<input type='hidden' name='page'>");
sb.append("</form>");
//分页条html代码拼接
sb.append("<div style='text-align: right; font-size: 12px;'>");
sb.append(" 每页"+pageBean.getRows()+"条，共"+pageBean.getTotal()+"条，第"+pageBean.getPage()+"页，共"+pageBean.getMaxPage()+"页 ");
sb.append(" <a href='javascript:gotoPage(1)'>首页</a> <a");
sb.append(" href='javascript:gotoPage("+pageBean.getPreviousPage()+")'>上一页</a> <a");
sb.append(" href='javascript:gotoPage("+pageBean.getNextPage()+")'>下一页</a> <a");
sb.append(" href='javascript:gotoPage("+pageBean.getMaxPage()+")'>尾页</a> <input type='text'");
sb.append(" id='skipPage'");
sb.append(" style='text-align: center; font-size: 12px; width: 50px;'> <a");
sb.append(" href='javascript:skipPage()'>Go</a>");
sb.append(" </div>");
//分页所需要调用的js代码
sb.append("<script type='text/javascript'>");
sb.append(" function gotoPage(page) {");
sb.append(" document.getElementById('pageBeanForm').page.value = page;");
sb.append(" document.getElementById('pageBeanForm').submit();");
sb.append(" }");
sb.append(" function skipPage() {");
sb.append(" var page = document.getElementById('skipPage').value;");
sb.append(" if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>"+pageBean.getMaxPage()+"){");
sb.append(" alert('请输入1~N的数字');");
sb.append(" return;");
sb.append(" }");
sb.append(" gotoPage(page);");
sb.append(" }");
sb.append("</script>");
return sb.toString();
}
public PageBean getPageBean() {
return pageBean;
}
public void setPageBean(PageBean pageBean) {
this.pageBean = pageBean;
}
}
标签描述文件(tld)
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>zking 1.1 core library</description>
<display-name>zking core</display-name>
<tlib-version>1.1</tlib-version>
<short-name>c</short-name>
<uri>/xuyang</uri><!-- 这是你引入标签库的语句 -->
<tag>
<name>page</name>
<tag-class>com.tag.PageTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>pageBean</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>
跳转的servlet页面
public class BookServlet extends HttpServlet {
private static final long serialVersionUID = -4443656491740044602L;
private BookDao bookDao=new BookDao();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String bname=req.getParameter("bname");
Book book=new Book();
book.setBname(bname);
PageBean pageBean=new PageBean();
pageBean.setRequest(req);
try {
// 查询出符合条件的某一页记录数
List<Book> list = bookDao.list(book, pageBean);//调用分页dao方法
req.setAttribute("bookList", list);
req.setAttribute("pagebean", pageBean);
req.getRequestDispatcher("bookList.jsp").forward(req, resp);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
在jsp页面引入标签库，测试是否能用
body>
<h2>小说目录</h2>
<br>
<form action="${pageContext.request.contextPath}/bookServlet"
method="post">
书名：<input type="text" name="bname"> <input type="submit"
value="确定">
</form>
<table border="1" width="100%">
<tr>
<td>编号</td>
<td>名称</td>
<td>价格</td>
</tr>
<c:forEach items="${bookList}" var="b">
<tr>
<td>${b.bid }</td>
<td>${b.bname }</td>
<td>${b.price }</td>
</tr>
</c:forEach>
</table>
<z:page pageBean="${pagebean}"></z:page>
</body>
结果：所有赋值数据全部正确了，模糊查后同样能翻页，说明这次定义标签是成功了
