Spring boot Mybatis 分页插件
之前博客 Spring boot 2 mybatis配置 讲到了连接数据库可以操作基本的增删改查，接下来讲一下怎么实现分页。
第一步：添加分页插件
引用开源插件地址：https://github.com/pagehelper/pagehelper-spring-boot
<!-- mybatis 分页插件 -->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.10</version>
</dependency>
第二步：自定义分页插件
/**
* @Description 分页工具
* @Date 2019/2/22 17:59
* @Created by gongxz
*/
@ApiModel(value = "PageList",description = "分页对象")
public class PageList<T> implements Serializable {
private static final long serialVersionUID = 1L;
@ApiModelProperty(value = "当前页",dataType = "int",name = "pageNum")
private int pageNum;
@ApiModelProperty(value = "每页的数量",dataType = "int",name = "pageSize")
private int pageSize;
@ApiModelProperty(value = "当前页的数量",dataType = "int",name = "size")
private int size;
@ApiModelProperty(value = "总页数",dataType = "int",name = "pages")
private int pages;
@ApiModelProperty(value = "总记录数",dataType = "long",name = "total")
private long total;
@ApiModelProperty(value = "结果集",dataType = "List",name = "list")
private List<T> list;
//@ApiModelProperty(value = "前一页",dataType = "int",name = "prePage")
//private int prePage;
//@ApiModelProperty(value = "下一页",dataType = "int",name = "nextPage")
//private int nextPage;
//@ApiModelProperty(value = "是否有前一页",dataType = "boolean",name = "hasPreviousPage")
//private boolean hasPreviousPage = false;
//@ApiModelProperty(value = "是否有下一页",dataType = "boolean",name = "hasNextPage")
//private boolean hasNextPage = false;
//由于startRow和endRow不常用，这里说个具体的用法
//可以在页面中"显示startRow到endRow 共size条数据"
//当前页面第一个元素在数据库中的行号
//private int startRow;
//当前页面最后一个元素在数据库中的行号
//private int endRow;
//是否为第一页
//private boolean isFirstPage = false;
//是否为最后一页
//private boolean isLastPage = false;
//导航页码数
//private int navigatePages;
//所有导航页号
//private int[] navigatepageNums;
//导航条上的第一页
//private int navigateFirstPage;
//导航条上的最后一页
//private int navigateLastPage;
/**
* 包装Page对象
*
* @param list page结果
*/
public PageList(List<T> list) {
this.list = list;
if (list instanceof Page) {
this.total = ((Page)list).getTotal();
} else {
this.total = (long)list.size();
}
if (list instanceof Page) {
Page page = (Page) list;
this.pageNum = page.getPageNum();
this.pageSize = page.getPageSize();
this.pages = page.getPages();
this.size = page.size();
//由于结果是>startRow的，所以实际的需要+1
/*if (this.size == 0) {
this.startRow = 0;
this.endRow = 0;
} else {
this.startRow = page.getStartRow() + 1;
//计算实际的endRow（最后一页的时候特殊）
this.endRow = this.startRow - 1 + this.size;
}*/
} else {
this.pageNum = 1;
this.pageSize = list.size();
this.pages = this.pageSize > 0 ? 1 : 0;
this.size = list.size();
//this.startRow = 0;
//this.endRow = list.size() > 0 ? list.size() - 1 : 0;
}
//this.navigatePages = navigatePages;
//计算导航页
//calcNavigatepageNums();
//计算前后页，第一页，最后一页
//calcPage();
//判断页面边界
//judgePageBoudary();
}
public int getPageNum() {
return this.pageNum;
}
public void setPageNum(int pageNum) {
this.pageNum = pageNum;
}
public int getPageSize() {
return this.pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getSize() {
return this.size;
}
public void setSize(int size) {
this.size = size;
}
public int getPages() {
return this.pages;
}
public void setPages(int pages) {
this.pages = pages;
}
public long getTotal() {
return this.total;
}
public void setTotal(long total) {
this.total = total;
}
public List<T> getList() {
return this.list;
}
public void setList(List<T> list) {
this.list = list;
}
public String toString() {
StringBuilder sb = new StringBuilder("PageInfo{");
sb.append("pageNum=").append(this.pageNum);
sb.append(", pageSize=").append(this.pageSize);
sb.append(", size=").append(this.size);
//sb.append(", startRow=").append(this.startRow);
//sb.append(", endRow=").append(this.endRow);
sb.append(", total=").append(this.total);
sb.append(", pages=").append(this.pages);
sb.append(", list=").append(this.list);
//sb.append(", prePage=").append(this.prePage);
//sb.append(", nextPage=").append(this.nextPage);
//sb.append(", isFirstPage=").append(this.isFirstPage);
//sb.append(", isLastPage=").append(this.isLastPage);
//sb.append(", hasPreviousPage=").append(this.hasPreviousPage);
//sb.append(", hasNextPage=").append(this.hasNextPage);
//sb.append(", navigatePages=").append(this.navigatePages);
//sb.append(", navigateFirstPage=").append(this.navigateFirstPage);
//sb.append(", navigateLastPage=").append(this.navigateLastPage);
sb.append(", navigatepageNums=");
/*if (this.navigatepageNums == null) {
sb.append("null");
} else {
sb.append('[');
for(int i = 0; i < this.navigatepageNums.length; ++i) {
sb.append(i == 0 ? "" : ", ").append(this.navigatepageNums[i]);
}
sb.append(']');
}*/
sb.append(", total=").append(this.total);
sb.append(", list=").append(this.list);
sb.append('}');
return sb.toString();
}
}
上面分页的实体类是拿开源插件里面自带的PageInfo类修改的，根据自己实际情况修改，也可以直接使用开源插件自带的PageInfo。
第三步 具体使用
- 使用自定义分页插件
@Override
public PageList<User> findAll() {
PageHelper.startPage(2, 8);
List<User> list = userDao.selectByExample(null);
//自定义分页插件
return new PageList<>(list);
}
- 使用自带的分页插件
public PageInfo<User> find() {
PageHelper.startPage(2, 8);
List<User> list = userDao.selectByExample(null);
//自定义分页插件
return new PageInfo<>(list);
}
使用自己定义的插件只是可以返回自己实际需要的分页信息，如果需要所有的分页信息，可以直接使用
PageInfo