通用分页 利用标签分页

通用分页一 已经把数据展示到页面上，并且能够按代码来规定查询多少条，
这次就就以a标签的形式，由用户来进行分页，

具体的思路
1、 对pagebean增强（添加url、paramMap属性，添加初始化pagebean的方法、最大页、上一页、下一页方法）
2、 将按钮条写入标签助手类
3、 将隐藏的form表单写入标签助手类
4、 将对应的js代码写入标签助手类
5、 测试通用分页是否完善

• 需要的类

•  PageBean 	BookServlet 	PageTag 	bookList
  

标签描述文件 z.tld

先把PageBean需要的方法写好

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<>();

	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;
	}

接下来就要写助手类，PageTag

public class PageTag extends BodyTagSupport {

	
	private static final long serialVersionUID = 602917970858963475L;
	private PageBean pageBean;
	
	@Override
	public int doStartTag() throws JspException {
		JspWriter out = pageContext.getOut();
		try {
			out.print(toHTML());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			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&&paramMap.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("</from>");
		
		//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&nbsp;&nbsp;<a");
		sb.append(" href='javascript:gotoPage(1)'>首页</a>&nbsp;&nbsp;<a");
		sb.append(" href='javascript:gotoPage("+pageBean.getPreviousPage()+")'>上一页</a>&nbsp;&nbsp;<a");
		sb.append(" href='javascript:gotoPage("+pageBean.getNextPage()+")'>下一页</a>&nbsp;&nbsp;<a");
		sb.append(" href='javascript:gotoPage("+pageBean.getMaxPage()+")'>尾页</a>&nbsp;&nbsp;<input type='text'");
		sb.append(" id='skipPage'");
		sb.append(" style='text-align: center; font-size: 12px; width: 50px;'>&nbsp;&nbsp;<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 null;
	}

	public PageBean getPageBean() {
		return pageBean;
	}
	public void setPageBean(PageBean pageBean) {
		this.pageBean = pageBean;
	}
	public static long getSerialversionuid() {
		return serialVersionUID;
	}

	public PageTag() {
		super();
	}

	
	
	
}

在写标签描述文件 tld，去写个标签，

  <description>zking 1.1 core library</description>
  <display-name>zking core</display-name>
  <tlib-version>1.1</tlib-version>
  <short-name>z</short-name>
  <uri>/zking</uri>
	

  <tag>
  	<name>page</name>
  	<tag-class>com.tzp.tags.PageTag</tag-class>
  	<body-content>JSP</body-content>
  	<attribute>
  		<name>pageBean</name>
  		<required>true</required>
  		<rtexprvalue>true</rtexprvalue>
  	</attribute>
  </tag>
  

控制类 BookServlet

public class BookServlet extends HttpServlet {
	
	private BookDao bd=new BookDao();
	
	private static final long serialVersionUID = 7111447857696817024L;
	
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		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的记录数
			List<Book> list = bd.list(book, pagebean);
			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 (SQLException e) {
			e.printStackTrace();
		}
		
	}
	
}

最后展示到页面 调用标签了进行展示到页面
记得要引用标签

  <%@ taglib uri="/zking" prefix="z" %>

下面的分页a标签都是可以进行使用了