spring mvc 分页

 

分页主要需要两个参数：

1、当前页是第几页

2、每页展示多少条数据

先写一个类来封装处理这两个参数:

 

 

package com.smvc.annonation.utils;

import java.io.Serializable;
import java.util.List;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class ResultFilter<T> implements Serializable{

	private static final long serialVersionUID = 5472321653620726832L;

	private final static int DEFAULT_NAVIGATOR_SIZE = 5;

	//当前页
    private int currentPage = 1;
    //每页显示数量
    private int pageSize = 5;
    
    //总条数
    private int totalCount;

    private boolean havaNextPage;

    private boolean havePrePage;

    private int navigatorSize;
    
    //存放查询结果用的list
    private List<T> items;
    
    public ResultFilter(){
    	
    }
    
    public ResultFilter(int totalCount, int pageSize, int currentPage) {
        this(totalCount, pageSize, currentPage, DEFAULT_NAVIGATOR_SIZE);
    }

    public ResultFilter(int totalCount, int pageSize, int currentPage,
                        int navigatorSize) {
        this.totalCount = totalCount;
        this.pageSize = pageSize;
        this.currentPage = currentPage;
        this.navigatorSize = navigatorSize;
    }
    
    public int getPageCount() {
        int pageCount = 0;
        if (pageSize != 0) {
            pageCount = totalCount / pageSize;
            if (totalCount % pageSize != 0)
                pageCount++;
        }

        return pageCount;
    }

    public int getCurrentPage() {
        currentPage = currentPage < getPageCount() ? currentPage :
                      getPageCount();
        currentPage = currentPage < 1 ? 1 : currentPage;

        return currentPage;
    }

    public int getPageSize() {
        return pageSize;
    }

    public int getTotalCount() {
        return totalCount;
    }


    public boolean isHaveNextPage() {
        havaNextPage = false;
        if ((getPageCount() > 1) && (getPageCount() > getCurrentPage()))
            havaNextPage = true;
        return havaNextPage;
    }

    public boolean isHavePrePage() {
        havePrePage = false;
        if ((getPageCount() > 1) && (currentPage > 1))
            havePrePage = true;
        return havePrePage;
    }

    private int getNavigatorIndex(boolean isBegin) {
        int beginNavigatorIndex = getCurrentPage() - navigatorSize / 2;
        int endNavigatorIndex = getCurrentPage() + navigatorSize / 2;
        beginNavigatorIndex = beginNavigatorIndex < 1 ? 1 : beginNavigatorIndex;
        endNavigatorIndex = endNavigatorIndex < getPageCount() ?
                            endNavigatorIndex :
                            getPageCount();
        while ((endNavigatorIndex - beginNavigatorIndex) < navigatorSize &&
               (beginNavigatorIndex != 1 || endNavigatorIndex != getPageCount())) {
            if (beginNavigatorIndex > 1)
                beginNavigatorIndex--;
            else if (endNavigatorIndex < getPageCount())
                endNavigatorIndex++;
        }

        if(isBegin)
            return beginNavigatorIndex;
        else
            return endNavigatorIndex;
    }

    public int getBeginNavigatorIndex() {
        return getNavigatorIndex(true);
    }

    public int getEndNavigatorIndex() {
        return getNavigatorIndex(false);
    }

    public List<T> getItems() {
        return items;
    }

    public void setItems(List<T> items) {
        this.items = items;
    }
    
	public void setCurrentPage(int currentPage) {
		this.currentPage = currentPage;
	}

	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}

	public void setTotalCount(int totalCount) {
		this.totalCount = totalCount;
	}

	@Override
	public String toString() {
		return ToStringBuilder.reflectionToString(this, ToStringStyle.MULTI_LINE_STYLE);
	}

}

 接着，就要处理如何翻页的问题。解决方法就是在页面间传递参数，传递当前是第几页。

 

使用自己定义标签实现比较简便（由于现在只做了一个页面，并不能保证翻页功能的通用性，以后会慢慢完善）

自定义标签的配置:

<?xml version="1.0" encoding="UTF-8"?>
<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>My Tag Library</description>
	<tlib-version>1.0</tlib-version>
	<short-name>my</short-name>
	<uri>my-taglib</uri>

	<tag>
		<description>split page</description>
		<name>paging</name>
		<tag-class>com.smvc.annonation.tag.PagingTag</tag-class>
		<body-content>empty</body-content>
		<attribute>
			<description>base href</description>
			<name>href</name>
			<required>false</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<attribute>
			<description>curr page</description>
			<name>curr</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<attribute>
			<description>page size</description>
			<name>size</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<attribute>
			<description>total page</description>
			<name>total</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<attribute>
			<description>curr parameter name</description>
			<name>cparam</name>
			<required>false</required>
			<rtexprvalue>false</rtexprvalue>
		</attribute>
		<attribute>
			<description>page size parameter name</description>
			<name>sparam</name>
			<required>false</required>
			<rtexprvalue>false</rtexprvalue>
		</attribute>
		<dynamic-attributes>false</dynamic-attributes>
	</tag>
	
	
	
	<tag>
		<description>front split page</description>
		<name>frontPaging</name>
		<tag-class>com.aspire.cms.demo.framework.tag.FrontPagingTag</tag-class>
		<body-content>empty</body-content>
		<attribute>
			<description>base href</description>
			<name>href</name>
			<required>false</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<attribute>
			<description>result filter</description>
			<name>rf</name>
			<required>true</required>
			<rtexprvalue>true</rtexprvalue>
		</attribute>
		<dynamic-attributes>false</dynamic-attributes>
	</tag>

</taglib>

 对应的java类：

package com.smvc.annonation.tag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.SimpleTagSupport;

import org.apache.commons.lang.StringUtils;

public class PagingTag extends SimpleTagSupport {
	
	private String href;
	
	//当前页
	private String cparam;
	//每页条数
	private String sparam;

	private int curr;//当前页
	
	private int size;//每页条数
	
	private int total;//总页数
	
	@Override
	public void doTag() throws JspException, IOException {
		JspWriter out = getJspContext().getOut();
		
		if(StringUtils.isEmpty(cparam)) {
			cparam = "currentPage";
		}
		if(StringUtils.isEmpty(sparam)) {
			sparam = "pageSize";
		}
		
		if(!href.endsWith("?") && !href.endsWith("&")) {
			if(href.indexOf("?") == -1) {
				href = href + "?";
			} else {
				href = href + "&";
			}
		}
		
		if (curr <= 0) {
			curr = 1;
		} else if (curr > total) {
			curr = total;
		}
		
		out.append("<span>");
		// 首页
		if (curr == 1) {
			out.append("首页");
		} else {
			href(out, href, 1, "首页");
		}
		out.append(" | ");
		// 上一页
		if (curr == 1) {
			out.append("上一页");
		} else {
			href(out, href, curr - 1, "上一页");
		}
		out.append(" | ");
		// 下一页
		if (curr == total) {
			out.append("下一页");
		} else {
			href(out, href, curr + 1, "下一页");
		}
		out.append(" | ");
		// 末页
		if (curr == total) {
			out.append("末页");
		} else {
			href(out, href, total, "末页");
		}
		out.append("</span>");
		out.append("<span>第");
		out.append(curr + "/" + total);
		out.append("页</span>");
		
		
		super.doTag();
	}
	
	private void href(JspWriter out, String href, int curr, String title) throws IOException {
		out.append("<a href=\"").append(href).append(cparam).append("=").append("" + curr).append("&").append(sparam).append("=").append("" + size).append("\">").append(title).append("</a>");
	}

	public int getCurr() {
		return curr;
	}

	public void setCurr(int curr) {
		this.curr = curr;
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public String getHref() {
		return href;
	}

	public void setHref(String href) {
		this.href = href;
	}

	public String getCparam() {
		return cparam;
	}

	public void setCparam(String cparam) {
		this.cparam = cparam;
	}

	public String getSparam() {
		return sparam;
	}

	public void setSparam(String sparam) {
		this.sparam = sparam;
	}

	public int getSize() {
		return size;
	}

	public void setSize(int size) {
		this.size = size;
	}

}

 在jsp中使用自定义的标签库来实现翻页功能：

list.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" %>
<%@ page session="false"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib uri="my-taglib" prefix="my"%>
<title>学生列表</title>
<form action="list" method="post">
<table>
<tr>
	<td width="160">id</td>
	<td width="160">姓名</td>
	<td width="160">性别</td>
	<td width="160">年龄</td>
	<td width="160">生日</td>
</tr>
<c:forEach items="${rf.items}" var="student">
<tr>
	<td><c:out value="${student.id}"/></td>
	<td><c:out value="${student.name}"/></td>
	<td><c:out value="${student.gender}"/></td>
	<td><c:out value="${student.age}"/></td>
	<td><fmt:formatDate value="${student.birthday}"  type="both" pattern="yyyy-MM-dd"/></td>
</tr>
</c:forEach>
</table>
<my:paging curr="${rf.currentPage}" total="${rf.pageCount}" size="${rf.pageSize}" href="list"/>
</form>

 controller中根据参数对ResultFilter进行设置:

@RequestMapping(value="/list")
	public ModelAndView listStudent(@ModelAttribute ResultFilter<Student> rf){
		studentService.listStudent(rf);
		return new ModelAndView("list", "rf", rf);
	}

 service中的方法:

	public void listStudent(ResultFilter<Student> rf){
		rf.setTotalCount(getStudentCount());
		rf.setItems(studentDao.getListForPage("from Student", (rf.getCurrentPage() - 1 )* rf.getPageSize(), rf.getPageSize()));
	}

 这个方法没有使用session,能支持多台服务器共同提供服务的情况。但是这个方法的效率可能有点低，因为每次翻页的时候都会重新创建一个ResultFilter，使用hibernate的缓存应该会使性能有所提高。