• jsp通用分页（下）

    目录

    一，通用分页前端

    1.pageBean工具分页类

    2.Servlet类

    3.pageTag类

    4. tld文件

    5.jsp界面

    前言：

    核心思想如图

     

    一，通用分页前端

     1.pageBean工具分页类

    1. package com.dengxiyan.util;
    2.  
    3. import java.util.HashMap;
    4. import java.util.Map;
    5.  
    6. import javax.servlet.http.HttpServletRequest;
    7.  
    8. /**
    9.  * 分页工具类
    10.  *
    11.  */
    12. public class PageBean {
    13.  
    14. 	private int page = 1;// 页码
    15.  
    16. 	private int rows = 10;// 页大小
    17.  
    18. 	private int total = 0;// 总记录数
    19.  
    20. 	private boolean pagination = true;// 是否分页
    21.  
    22. //	需要新增变量保存上一次请求地址：http://localhost;80/...
    23. 	private String url;
    24. 	
    25. 	//保留上一次查询的条件      //需要新增变量保存上一次查询条件
    26. 	private Map<String, String[]> parameterMap = new HashMap<String, String[]>();
    27. 	
    28. //	需要添加方法：获取最大页的页码
    29. 	public int maxPage() {
    30. 		return this.total % this.rows ==0 ? this.total / this.rows : this.total / this.rows + 1;
    31. 		
    32. 	}
    33.  
    34. //	需要添加方法：获取上一页的页码
    35. 	public int previousPage() {
    36. 		return this.page > 1 ? this.page - 1 : this.page;
    37. 	}
    38.  
    39. //	需要添加方法：获取下一页的页码
    40. 	public int nextPage() {
    41. 		return this.page < this.maxPage() ? this.page + 1 : this.page;
    42. 	}
    43.  
    44. //	需要新增方法：初始化pagebean
    45.  
    46. 	public void setRequest(HttpServletRequest req) {
    47. 		this.setPage(req.getParameter("page"));
    48. 		this.setRows(req.getParameter("rows"));
    49. 		this.setPagination(req.getParameter("page"));
    50. 		this.setUrl(req.getRequestURL().toString());
    51. 		this.setParameterMap(req.getParameterMap());
    52. 	}
    53. 	
    54. 	
    55. 	
    56. 	private void setPagination(String page) {
    57. 	
    58. 		if(StringUtils.isNotBlank(page)) {
    59.     //此处判断意为：当条件不为false时就进行分页，所以非字符不能少
    60. 			this.setPagination(!"false".equals(page));
    61. 		}
    62. }
    63.  
    64. 	private void setRows(String rows) {
    65. 		if(StringUtils.isNotBlank(rows)) {
    66. 			this.setRows(Integer.valueOf(rows));
    67. 	}
    68. }
    69.  
    70. 	public void setPage(String page) {
    71. 		if(StringUtils.isNotBlank(page))
    72. 			//set自动生成的方法
    73. 			this.setPage(Integer.valueOf(page));
    74. 	}
    75.  
    76. 	public PageBean() {
    77. 		super();
    78. 	}
    79. 	
    80. 	public String getUrl() {
    81. 		return url;
    82. 	}
    83.  
    84. 	public void setUrl(String url) {
    85. 		this.url = url;
    86. 	}
    87.  
    88. 	public Map<String, String[]> getParameterMap() {
    89. 		return parameterMap;
    90. 	}
    91.  
    92. 	public void setParameterMap(Map<String, String[]> parameterMap) {
    93. 		this.parameterMap = parameterMap;
    94. 	}
    95.  
    96. 	public int getPage() {
    97. 		return page;
    98. 	}
    99.  
    100. 	public void setPage(int page) {
    101. 		this.page = page;
    102. 	}
    103.  
    104. 	public int getRows() {
    105. 		return rows;
    106. 	}
    107.  
    108. 	public void setRows(int rows) {
    109. 		this.rows = rows;
    110. 	}
    111.  
    112. 	public int getTotal() {
    113. 		return total;
    114. 	}
    115.  
    116. 	public void setTotal(int total) {
    117. 		this.total = total;
    118. 	}
    119.  
    120. 	public void setTotal(String total) {
    121. 		this.total = Integer.parseInt(total);
    122. 	}
    123.  
    124. 	public boolean isPagination() {
    125. 		return pagination;
    126. 	}
    127.  
    128. 	public void setPagination(boolean pagination) {
    129. 		this.pagination = pagination;
    130. 	}
    131.  
    132. 	/**
    133. 	 * 获得起始记录的下标
    134. 	 * 
    135. 	 * @return
    136. 	 */
    137. 	public int getStartIndex() {
    138. 		return (this.page - 1) * this.rows;
    139. 	}
    140.  
    141. 	@Override
    142. 	public String toString() {
    143. 		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination
    144. 				+ ", url=" + url + ", parameterMap=" + parameterMap + "]";
    145. 	}
    146.  
    147. 	
    148. }

    《代码分析如下》 

    需要新增变量保存上一次查询的条件

    private Map<String, String[]> parameterMap = new HashMap<String, String[]>();

    需要新增变量保存上一次请求的地址

    1. private String url;
    2.  
    3. public String getUrl() {
    4. 		return url;
    5. 	}
    6.  
    7. 	public void setUrl(String url) {
    8. 		this.url = url;
    9. 	}

    需要添加方法，获取最大页码的页码

    总页码%页码大小，能被整除的情况下返回被整除的结果。否则就在返回的结果加1

    1. public int maxPage() {
    2. 		return this.total % this.rows ==0 ? this.total / this.rows : this.total / this.rows + 1;
    3. 		
    4. 	}

    需要添加方法：获取上一页的页码

    如果当前页大于1的情况下当前页-1，否则就为当前页

    1. public int previousPage() {
    2. 		return this.page > 1 ? this.page - 1 : this.page;
    3. 	}

    需要添加方法：获取下一页的页码

    如果当前页码小于最大页码数时当前页码就+1，否则就为当页码

    1. public int nextPage() {
    2. 		return this.page < this.maxPage() ? this.page + 1 : this.page;
    3. 	}

    需要新增方法：初始化pagebean

    提示：在判断是，如果只有一条代码的情况下可以不加花括号

    1. public void setRequest(HttpServletRequest req) {
    2. 		this.setPage(req.getParameter("page"));
    3. 		this.setRows(req.getParameter("rows"));
    4. 		this.setPagination(req.getParameter("page"));
    5. 		this.setUrl(req.getRequestURL().toString());
    6. 		this.setParameterMap(req.getParameterMap());
    7. 	}
    8.  
    9.  
    10. private void setPagination(String page) {
    11.         判断如果不为空
    12. 		if(StringUtils.isNotBlank(page)) {
    13.         就调用它先=现有的方法
    14. 			this.setPagination(!"false".equals(page));
    15. 		}
    16. }
    17.  
    18. private void setRows(String rows) {
    19. 		if(StringUtils.isNotBlank(rows)) {
    20. 			this.setRows(Integer.valueOf(rows));
    21. 	}
    22. }
    23.     //相当于一个重载的方法
    24. 	public void setPage(String page) {
    25. 		if(StringUtils.isNotBlank(page))
    26. 			//set自动生成的方法(并非自己掉自己)
    27. 			this.setPage(Integer.valueOf(page));
    28. 	}

    2.Servlet类

    《代码演示》

    提示：PageBean pageBean = new PageBean();
                    pageBean.setRequest(req);    这里实例化了分页工具类，然后调用了初始化pagebean的方法，req里面就带着前台jsp传过来的值

    1. package com.dengxiyan.web;
    2.  
    3. import java.io.IOException;
    4. import java.util.List;
    5. import java.util.Map;
    6.  
    7. import javax.servlet.ServletException;
    8. import javax.servlet.annotation.WebServlet;
    9. import javax.servlet.http.HttpServlet;
    10. import javax.servlet.http.HttpServletRequest;
    11. import javax.servlet.http.HttpServletResponse;
    12.  
    13. import com.dengxiyan.dao.BookDao;
    14. import com.dengxiyan.entity.Book;
    15. import com.dengxiyan.util.PageBean;
    16.  
    17. @WebServlet("/book/search")
    18. public class BookServlet extends HttpServlet{
    19.  
    20. 	@Override
    21. 	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    22. 		doPost(req, resp);
    23. 	}
    24.  
    25. 	
    26. 	@Override
    27. 	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    28. 		PageBean pageBean = new PageBean();
    29. 		pageBean.setRequest(req);
    30. 		BookDao bd = new BookDao();
    31. 		Book book = new Book();
    32. 		book.setBname(req.getParameter("bname"));
    33. 		try {
    34. 			List<Book> books = bd.list2(book, pageBean);
    35. 			req.setAttribute("books", books);
    36. 		} catch (Exception e) {
    37. 			// TODO Auto-generated catch block
    38. 			e.printStackTrace();
    39. 		}
    40. 		
    41. 		req.setAttribute("pagebean", pageBean);
    42. 		req.getRequestDispatcher("/booklist.jsp").forward(req, resp);
    43. 	}
    44. }

    3.pageTag类

    《代码如下》

    将jsp界面的代码拿过来，同时要将它转换为页面上的html。将代码放进来是一定要细心

    提示：如果当前页与最大页码相等时，就禁用按钮，否则啥也没有

    首页的话就==1的时候

    sb.append("	<li class='page-item "+(pagebean.getPage() == pagebean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pagebean.nextPage()+")'>&gt;</a></li>");

    1. package com.dengxiyan.tag;
    2.  
    3. import java.io.IOException;
    4. import java.util.Map;
    5. import java.util.Map.Entry;
    6. import java.util.Set;
    7.  
    8. import javax.servlet.jsp.JspException;
    9. import javax.servlet.jsp.JspWriter;
    10. import javax.servlet.jsp.tagext.BodyTagSupport;
    11.  
    12. import com.dengxiyan.util.PageBean;
    13.  
    14. public class PageTag extends BodyTagSupport {
    15.  
    16. 	private PageBean pagebean;
    17. 	
    18. 	
    19. 	public PageBean getPagebean() {
    20. 		return pagebean;
    21. 	}
    22.  
    23. 	public void setPagebean(PageBean pagebean) {
    24. 		this.pagebean = pagebean;
    25. 	}
    26.  
    27. 	@Override
    28. 	public int doStartTag() throws JspException {
    29. 		JspWriter out = pageContext.getOut();
    30. 		try {
    31. 			out.print(toHTML());
    32. 		} catch (IOException e) {
    33. 			// TODO Auto-generated catch block
    34. 			e.printStackTrace();
    35. 		}
    36. 		return super.doStartTag();
    37. 	}
    38.  
    39. 	private String toHTML() {
    40. 		StringBuffer sb = new StringBuffer();
    41. 		//隐藏的form表单，作用是，保存上一次的查询条件
    42. 		sb.append("<form action='"+pagebean.getUrl()+"' id='pageBeanForm' method='post'>");
    43. 		sb.append("		<input type='hidden' name='page' value=''>");
    44. 		Map<String, String[]> parameterMap = pagebean.getParameterMap();
    45. 		if(parameterMap != null && parameterMap.size() >0) {
    46. 			Set<Entry<String,String[]>> entrySet = parameterMap.entrySet();
    47. 			for (Entry<String, String[]> entry : entrySet) {
    48. 				String key = entry.getKey();//name/likes/page/rows
    49. 				String[] values = entry.getValue();
    50. 				if(!"page".equals(key)) {
    51. 					for (String value: values) {
    52. 						sb.append("		<input type='hidden' name='"+key+"' value=''>");
    53. 						
    54. 					}
    55. 				}
    56. 			}
    57. 		}
    58. 		sb.append("</form>");
    59. 		
    60. 		//分页条
    61. 		sb.append("<ul class='pagination justify-content-center'>");
    62. 		sb.append("	<li class='page-item "+(pagebean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    63. 		sb.append(" 	href='javascript:gotoPage(1)'>首页</a></li>");
    64. 		sb.append("	<li class='page-item "+(pagebean.getPage() == 1 ? "disabled" : "")+"'><a class='page-link'");
    65. 		sb.append("		href='javascript:gotoPage("+pagebean.previousPage()+")'>&lt;</a></li>");
    66. 		sb.append("	<li class='page-item'><a class='page-link' href='#'></a></li>");
    67. 		sb.append(" <li class='page-item active'><a class='page-link' href='#'>"+pagebean.getPage()+"</a></li>");
    68. 		sb.append("	<li class='page-item "+(pagebean.getPage() == pagebean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pagebean.nextPage()+")'>&gt;</a></li>");
    69. 		sb.append("	<li class='page-item "+(pagebean.getPage() == pagebean.maxPage() ? "disabled" : "")+"'><a class='page-link' href='javascript:gotoPage("+pagebean.maxPage()+")'>尾页</a></li>");
    70. 		sb.append("	<li class='page-item go-input'><b>到第</b><input class='page-link'");
    71. 		sb.append("		type='text' id='skipPage' name='' /><b>页</b></li>");
    72. 		sb.append("	<li class='page-item go'><a class='page-link'");
    73. 		sb.append("		href='javascript:skipPage()'>确定</a></li>");
    74. 		sb.append("	<li class='page-item'><b>共"+pagebean.getTotal()+"条</b></li>");
    75. 		sb.append("</ul>");
    76. 		
    77. 		
    78. 		//分页jsp代码
    79. 		sb.append("<script type='text/javascript'>");
    80. 		sb.append(" function gotoPage(page) {");
    81. 		sb.append(" 	document.getElementById('pageBeanForm').page.value = page;");
    82. 		sb.append("		document.getElementById('pageBeanForm').submit();");
    83. 		sb.append("	}");
    84. 		sb.append("	function skipPage() {");
    85. 		sb.append("			var page = document.getElementById('skipPage').value;");
    86. 		sb.append("			if (!page || isNaN(page) || parseInt(page) < 1");
    87. 		sb.append("				|| parseInt(page) > "+pagebean.maxPage()+") {");
    88. 		sb.append("				alert('请输入1~"+pagebean.maxPage()+"的数字');");
    89. 		sb.append("			return;");
    90. 		sb.append("		}");
    91. 		sb.append("		gotoPage(page);");
    92. 		sb.append(" }");
    93. 		sb.append("</script>");
    94. 		
    95. 		return sb.toString();
    96. 	}
    97. }

    4. tld文件

    1. <?xml version="1.0" encoding="UTF-8" ?>
    2.  
    3. <taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    4.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    5.     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    6.     version="2.0">
    7.     
    8.   <description>JSTL 1.1 core library</description>
    9.   <display-name>JSTL core</display-name>
    10.   <tlib-version>1.1</tlib-version>
    11.   <short-name>z</short-name>
    12.   <uri>http://jsp.veryedu.cn</uri>
    13.  
    14.   <validator>
    15.     <description>
    16.         Provides core validation features for JSTL tags.
    17.     </description>
    18.     <validator-class>
    19.         org.apache.taglibs.standard.tlv.JstlCoreTLV
    20.     </validator-class>
    21.   </validator>
    22.  
    23.   
    24.   
    25.   <tag>
    26.     <name>page</name>
    27.     <tag-class>com.dengxiyan.tag.PageTag</tag-class>
    28.     <body-content>JSP</body-content>
    29.     <attribute>
    30.         <name>pagebean</name>
    31.         <required>true</required>
    32.         <rtexprvalue>true</rtexprvalue>
    33.     </attribute>
    34.   </tag>
    35.   
    36.   
    37.  
    38. </taglib>

    5.jsp界面

    1. <%@ page language="java" contentType="text/html; charset=UTF-8"
    2. 	pageEncoding="UTF-8"%>
    3. 	<%@taglib uri="http://jsp.veryedu.cn" prefix="z"%>
    4. 	<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
    5. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    6. <html>
    7. <head>
    8. <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    9. <link
    10. 	href="css/bootstrap.css"
    11. 	rel="stylesheet">
    12. <script
    13. 	src="js/bootstrap.js"></script>
    14. <title>书籍列表</title>
    15. <style type="text/css">
    16. .page-item input {
    17. 	padding: 0;
    18. 	width: 40px;
    19. 	height: 100%;
    20. 	text-align: center;
    21. 	margin: 0 6px;
    22. }
    23.  
    24. .page-item input, .page-item b {
    25. 	line-height: 38px;
    26. 	float: left;
    27. 	font-weight: 400;
    28. }
    29.  
    30. .page-item.go-input {
    31. 	margin: 0 10px;
    32. }
    33. </style>
    34. </head>
    35. <body>
    36. <c:if test="${empty books}">
    37. <jsp:forward page="book/search"></jsp:forward>
    38. </c:if>
    39.  
    40. 	<form class="form-inline"
    41. 		action="${pageContext.request.contextPath }/book/search" method="post">
    42. 		<div class="form-group mb-2">
    43. 			<input type="text" class="form-control-plaintext" name="bname"
    44. 				placeholder="请输入书籍名称">
    45. 		</div>
    46. 		<button type="submit" class="btn btn-primary mb-2">查询</button>
    47. 	</form>
    48.  
    49. 	<table class="table table-striped bg-success">
    50. 		<thead>
    51. 			<tr>
    52. 				<th scope="col">书籍ID</th>
    53. 				<th scope="col">书籍名</th>
    54. 				<th scope="col">价格</th>
    55. 			</tr>
    56. 		</thead>
    57. 		<tbody>
    58. 		<c:forEach items="${books}" var="b">
    59. 			<tr>
    60. 				<td>${b.bid}</td>
    61. 				<td>${b.bname}</td>
    62. 				<td>${b.price}</td>
    63. 			</tr>
    64. 			</c:forEach>
    65. 		</tbody>
    66. 	</table>
    67. 	
    68. 	<z:page pagebean="${pagebean}"></z:page>
    69. 	
    70. </body>
    71. </html>

     

    《效果图如下》

     

     

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  • 原文地址：https://blog.csdn.net/weixin_66202611/article/details/125441117