PageHelper

ゝ一纸荒年。 2024-02-19 16:03 26阅读 0赞

**一.maven依赖**

<dependency>  
<groupId>com.github.pagehelper</groupId>  
<artifactId>pagehelper-spring-boot-starter</artifactId>  
<version>1.2.3</version>  
</dependency>

**二.application.yml配置**

\#pagehelper分页插件注入  
pagehelper:  
helperDialect: mysql  
reasonable: true  
supportMethodsArguments: true  
params: count=countSql

**三.后端功能**

分页方式1

@Override  
public List<JmrhAmonutData> findAll() \{  
PageHelper.startPage(1, 3);// 改写语句实现分页查询  
return jmrhAmonutDataMapper.findAll();//mybatis的mapper里的方法  
\}

结果:Page\{count=true, pageNum=1, pageSize=3, startRow=0, endRow=3, total=4, pages=2, reasonable=true, pageSizeZero=false\}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI0MTc0MDU_size_16_color_FFFFFF_t_70][]

分页方式2

PageHelper.startPage(2 , 3);mybatis  
List<JmrhAmonutData> personList = jmrhAmonutDataMapper.findAll();//mybatis的mapper里的方法  
//得到分页的结果对象  
PageInfo<JmrhAmonutData> personPageInfo = new PageInfo<>(personList);  
//得到分页中的person条目对象  
List<JmrhAmonutData> pageList = personPageInfo.getList();

结果:Page\{count=true, pageNum=2, pageSize=3, startRow=3, endRow=6, total=4, pages=2, reasonable=true, pageSizeZero=false\}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI0MTc0MDU_size_16_color_FFFFFF_t_70 1][]

以上两种方式是基于mybatis的mapper写的方法;第三种是直接掉jdbcTemplate写的方式

分页方式3

Page<Object> startPage3 = PageHelper.startPage(3 , 3);  
String sql=" select \* from jmrh\_data\_form ";  
List<Map<String, Object>> queryForList1 = jdbcTemplate.queryForList(sql);  
startPage3.setTotal(queryForList1.size());  
startPage3.setPages(queryForList1.size()%startPage3.getPageSize()==0?queryForList1.size()/startPage3.getPageSize():((queryForList1.size()/startPage3.getPageSize())+1));  
sql+=" limit "+startPage3.getStartRow()+","+startPage3.getPageSize()+" ";  
queryForList1=jdbcTemplate.queryForList(sql);

//将List<map>转换为List<Object> 这一步可转可不转  
List<jmrh\_data\_form> mapsToObjects = mapsToObjects(queryForList1 , jmrh\_data\_form.class);  
startPage3.addAll(mapsToObjects);

返回结果是startPage3

Page\{count=true, pageNum=3, pageSize=3, startRow=6, endRow=9, total=23, pages=8, reasonable=null, pageSizeZero=null\}

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI0MTc0MDU_size_16_color_FFFFFF_t_70 2][]

工具类:

/\*\*  
\* 将List<Map<String,Object>>转换为List<T>  
\* @param maps  
\* @param clazz  
\* @return  
\* @throws InstantiationException  
\* @throws IllegalAccessException  
\*/  
public static <T> List<T> mapsToObjects(List<Map<String, Object>> maps,Class<T> clazz) throws InstantiationException, IllegalAccessException \{  
List<T> list = new ArrayList<T>();  
if (maps != null && maps.size() > 0) \{  
Map<String, Object> map = null;  
T bean = null;  
for (int i = 0,size = maps.size(); i < size; i++) \{  
map = maps.get(i);  
bean = clazz.newInstance();  
mapToBean(map, bean);  
list.add(bean);  
\}  
\}  
return list;  
\}  
/\*\*  
\* 将map装换为javabean对象  
\* @param map  
\* @param bean  
\* @return  
\*/  
public static <T> T mapToBean(Map<String, Object> map,T bean) \{  
BeanMap beanMap = BeanMap.create(bean);  
beanMap.putAll(map);  
return bean;  
\}

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTI0MTc0MDU_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/1167e54f103a40fb871817ba1ffadeb3.png