mybatis逻辑分页,含分页导航

mybatis是非常优秀的半orm框架,比hibernate更容易控制,性能也很好,但mybatis官方并没提供分页功能,需要自己实现,下面提供一种物理分页的实现思路:

(基于sping、spring mvc、mybatis的整合,将PO)

1. 编写一个Pagination.java的实体类,含有页面显示数、总页数、当前页、开始行、结束行等属性

2. sql里加上分页参数

3. PO对象里加上这个分页对象

4. 在Service里,执行查询前,将分页实例的总记录数set进去,当前页由页面传入,这样就有了三个必备参数:总记录数、每页显示数(可以设一个默认值)、当前页,就可以获取sql查询时开始行、结束行,就实现分页了。

优点:

不改动mybatis框架代码,对service的实现类改动很小,只需加入一行代码,对controller改个只需model里add两个attribute,尽量做到低侵入低耦合。分页导航自动生成,可重新设置每页显示数,从不分页改为分页尽可能减少代码的增加工作。

缺点:

暂时只适用于持久化对象和表单视图对象共用,即持久化对象既用于数据库交互,也用于表单数据绑定。

下面为实例说明:

1. 在对象里加入一个属性:

...
	/** 用于分页 */
	private Pagination pagination = new Pagination();

	public Pagination getPagination() {
		return pagination;
	}

	public void setPagination(Pagination pagination) {
		this.pagination = pagination;
	}

此处初始化了,是为了不用判断是否为null,相当于给一个初始值。 

2.  在mapper.xml文件中加入分页语句本例以mysql(limit #{offSet}, #{pageSize})为例

<select id="getUserInfoList" parameterType="com.jayung.pagination.domain.UserInfo"
		 resultType="com.jayung.pagination.domain.UserInfo">
		select user_id userId, user_name userName, password password, 
		   age age 
		  from user_info 
		 <trim prefix="where" suffixOverrides="and">
		 	<if test="userId!=null and userId!=''">user_id = #{userId} and </if>
		 	<if test="userName!=null and userName!=''">user_name = #{userName} and </if>
		 	<if test="password!=null and password!=''">password = #{password} and </if>
		 	<if test="age!=null and age!=''">age = #{age} and </if>
		 </trim>
		 limit #{pagination.startRow}, #{pagination.pageSize}
	</select>

 其中limit #{pagination.startRow}, #{pagination.pageSize}是分页的两个参数;

3. 定义取总记录数的SQL

<select id="getUserInfoListCount" parameterType="com.jayung.pagination.domain.UserInfo"
		 resultType="java.lang.Integer">
		select count(1)
		  from user_info 
		 <trim prefix="where" suffixOverrides="and">
		 	<if test="userId!=null and userId!=''">user_id = #{userId} and </if>
		 	<if test="userName!=null and userName!=''">user_name = #{userName} and </if>
		 	<if test="password!=null and password!=''">password = #{password} and </if>
		 	<if test="age!=null and age!=''">age = #{age} and </if>
		 </trim>
	</select>

 与上面SQL的差别是将查询结果集换成了count记录集的总数;

3. serviceimpl

public List<UserInfo> getUserInfoList(UserInfo userInfo) {
		userInfo.getPagination().setTotalRow(userInfoMapper.getUserInfoListCount(userInfo));
		return userInfoMapper.getUserInfoList(userInfo);
	}

 4. controller

@RequestMapping(value = "/demo/userInfo/search")
	public String search(Model model, UserInfo userInfo, HttpServletRequest request) {
		// userInfo里含有pagination属性。
		model.addAttribute("userInfoList", userInfoService.getUserInfoList(userInfo));
		// pagination是分页对象
		model.addAttribute("pagination", userInfo.getPagination());
		// paginationForm是为了不丢失从查询页面传过来的查询参数,并保存当前页、每页显示数的信息
		model.addAttribute("paginationForm", PaginationUtil.getPaginationForm(request));
		return  "/demo/userInfo/userInfoList";
	}

5. paginationUtil用于保存来自源页面的参数,防止翻到第二页时丢失。

public static String getPaginationForm(HttpServletRequest request) {
		StringBuffer form = new StringBuffer();
		form.append("<form name=\"_paginationForm\" id=\"_paginationForm\" method=\"post\" aciton=\""
				+ new UrlPathHelper().getOriginatingRequestUri(request) + "\">\n");
		Enumeration paramNames = request.getParameterNames();
		while (paramNames.hasMoreElements()) {
			String paramName = (String) paramNames.nextElement();
			String paramValue = request.getParameter(paramName);
			if (!"pagination.pageSize".equals(paramName) && !"pagination.currentPage".equals(paramName)) {
				form.append("	<input type=\"hidden\" name=\"" + paramName + "\" value=\"" + paramValue + "\" />\n");
			}
		}
		String pageSize = (request.getParameter("pagination.pageSize") == null) ? Constant.PAGE_SIZE_DEFAULT.toString()
				: request.getParameter("pagination.pageSize");
		String currentPage = (request.getParameter("pagination.currentPage") == null) ? "1" : request
				.getParameter("pagination.currentPage");
		form.append("	<input type=\"hidden\" id=\"_pagination.pageSize\" name=\"pagination.pageSize\" value=\"" + pageSize + "\" />\n");
		form.append("	<input type=\"hidden\" id=\"_pagination.currentPage\" name=\"pagination.currentPage\" value=\"" + currentPage + "\" />\n");
		form.append("</form>");
		return form.toString();
	}

6. 分页页面

<table class="tableList" id="userInfoList">
	<tr>
			<th>userId</th>
			<th>userName</th>
			<th>password</th>
			<th>age</th>
		<th>操作</th>
	<tr>
		<c:forEach items="${userInfoList}" var="userInfo" varStatus="status">
		<tr id="${status.index}">
			<td>${userInfo.userId}</td>
			<td>${userInfo.userName}</td>
			<td>${userInfo.password}</td>
			<td>${userInfo.age}</td>
			<td><a href="${userInfo.userId}">查看</a> 
			<a href="${userInfo.userId}/edit">编辑</a> 
			<a href="javascript:void();" onclick="deleteRow('${userInfo.userId}','${status.index}');">删除</a></td>
		</tr>
		</c:forEach>
	</table>
	<div>${pagination.navigator}</div>
${paginationForm}

 ${pagination.navigator}是分页导航

${paginationForm}是分页表单

最后上传完整工程附件,含初始化sql脚本

欢迎大家讨论优化。

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