小編這次要給大家分享的是Java如何使用MyBatis框架分頁，文章內(nèi)容豐富，感興趣的小伙伴可以來了解一下，希望大家閱讀完這篇文章之后能夠有所收獲。
創(chuàng)新互聯(lián)建站主營(yíng)汕尾網(wǎng)站建設(shè)的網(wǎng)絡(luò)公司,主營(yíng)網(wǎng)站建設(shè)方案,成都App定制開發(fā),汕尾h5微信小程序開發(fā)搭建,汕尾網(wǎng)站營(yíng)銷推廣歡迎汕尾等地區(qū)企業(yè)咨詢
初始準(zhǔn)備
1.創(chuàng)建分頁對(duì)象類，方便模塊間傳值
重慶分公司
重慶分公司
//PageInfo.java
import lombok.Data;
@Data
public class PageInfo {
private int pageNo;
private int pageSize;
}2.定義DAO層接口
import org.apache.ibatis.session.RowBounds;
import org.springframework.stereotype.Repository;
import java.util.List;
@Repository
public interface UserMapper {
User selectByUser(User user);
List selectAll();
List selectByPageInfo(PageInfo info);
List selectByInterceptor(PageInfo info);
List selectByRowBounds(RowBounds rowBounds);
} 3.mapper中定義結(jié)果集合BaseResult
一、原始切分：最原始方法，不建議使用
1.mapper代碼:查詢所有數(shù)據(jù)
2.業(yè)務(wù)層代碼:利用List的subList()方法對(duì)數(shù)據(jù)進(jìn)行切片
public ListfindByAll(PageInfo info) { List users = userMapper.selectAll(); return users.subList(info.getPageNo(), info.getPageSize()); }
3.控制層代碼
@RequestMapping(value = "/userlist_1", method = RequestMethod.GET)
@ResponseBody
public Result findUserBySubList(PageInfo info) {
List users = userService.findByAll(info);
if(users.size() == 0) {
return ResultGenerator.genFailResult("未查找到用戶");
}
return ResultGenerator.genSuccessResult(users);
} 二、LIMIT關(guān)鍵字
1.mapper代碼:利用limit關(guān)鍵字實(shí)現(xiàn)分頁
2.業(yè)務(wù)層直接調(diào)用
public ListfindByPageInfo(PageInfo info) { return userMapper.selectByPageInfo(info); }
3.控制層直接調(diào)用
三、RowBounds實(shí)現(xiàn)分頁
1.在DAO層定義好所要傳輸?shù)姆猪撔畔?，類型為RowBounds
2.mapper層：查詢所有數(shù)據(jù)
3.業(yè)務(wù)層：將PageInfo信息封裝成RowBounds,調(diào)用DAO層方法
public ListfindByRowBounds(PageInfo info) { return userMapper.selectByRowBounds(new RowBounds(info.getPageNo(), info.getPageSize())); }
4.控制層直接調(diào)用
四、MyBatis的Interceptor實(shí)現(xiàn):實(shí)現(xiàn)復(fù)雜，需要明白MyBatis的實(shí)現(xiàn)
1.創(chuàng)建Interceptor
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;
import java.sql.Connection;
import java.util.Properties;
/**
* 利用MyBatis攔截器進(jìn)行分頁
*
* @Intercepts 說明是一個(gè)攔截器
* @Signature 攔截器的簽名
* type 攔截的類型 四大對(duì)象之一( Executor,ResultSetHandler,ParameterHandler,StatementHandler)
* method 攔截的方法
* args 參數(shù),高版本需要加個(gè)Integer.class參數(shù),不然會(huì)報(bào)錯(cuò)
*
*/
@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})})
public class DefinedPageInterceptor implements Interceptor {
@Override
public Object intercept(Invocation invocation) throws Throwable {
//獲取StatementHandler,默認(rèn)的是RoutingStatementHandler
StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
//獲取StatementHandler的包裝類
MetaObject metaObject = SystemMetaObject.forObject(statementHandler);
//分隔代理對(duì)象
while (metaObject.hasGetter("h")) {
Object obj = metaObject.getValue("h");
metaObject = SystemMetaObject.forObject(obj);
}
while (metaObject.hasGetter("target")) {
Object obj = metaObject.getValue("target");
metaObject = SystemMetaObject.forObject(obj);
}
//獲取查看接口映射的相關(guān)信息
MappedStatement mappedStatement = (MappedStatement) metaObject.getValue("delegate.mappedStatement");
String mapId = mappedStatement.getId();
//攔截以ByInterceptor結(jié)尾的請(qǐng)求，統(tǒng)一實(shí)現(xiàn)分頁
if (mapId.matches(".+ByInterceptor$")) {
System.out.println("LOG:已觸發(fā)分頁攔截器");
//獲取進(jìn)行數(shù)據(jù)庫(kù)操作時(shí)管理參數(shù)的Handler
ParameterHandler parameterHandler = (ParameterHandler) metaObject.getValue("delegate.parameterHandler");
//獲取請(qǐng)求時(shí)的參數(shù)
PageInfo info = (PageInfo) parameterHandler.getParameterObject();
//獲取原始SQL語句
String originalSql = (String) metaObject.getValue("delegate.boundSql.sql");
//構(gòu)建分頁功能的SQL語句
String sql = originalSql.trim() + " limit " + info.getPageNo() + ", " + info.getPageSize();
metaObject.setValue("delegate.boundSql.sql", sql);
}
//調(diào)用原對(duì)象方法，進(jìn)入責(zé)任鏈下一級(jí)
return invocation.proceed();
}
@Override
public Object plugin(Object target) {
//生成Object對(duì)象的動(dòng)態(tài)代理對(duì)象
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
//如果分頁每頁數(shù)量是統(tǒng)一的，可以在這里進(jìn)行統(tǒng)一配置，也就無需再傳入PageInfo信息了
}
}2.將Interceptor添加至MyBatisConfig中，這里采用JavaConfig的方式
@Bean
public SqlSessionFactoryBean sqlSession() {
SqlSessionFactoryBean sqlSession = new SqlSessionFactoryBean();
sqlSession.setDataSource(dataSource());
try {
Resource[] resources = new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml");
sqlSession.setMapperLocations(resources);
//配置自定義的Interceptro作為MyBatis的Interceptor,完成分頁操作
DefinedPageInterceptor definedPageInterceptor = new DefinedPageInterceptor();
sqlSession.setPlugins(new Interceptor[]{definedPageInterceptor});
return sqlSession;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}3.DAO層接口方法名需要和代碼中自定義的".+ByInterceptor$"正則表達(dá)式相匹配,mapper的書寫依然是查詢所有數(shù)據(jù)
4.業(yè)務(wù)層直接調(diào)用
5.控制層直接調(diào)用
五、開源項(xiàng)目PageHelper實(shí)現(xiàn)：本質(zhì)還是自己封裝了個(gè)Interceptor
1.引入PageHelper的jar包
com.github.pagehelper pagehelper 5.1.10
2.配置PageInterceptor
public PageInterceptor initPageInterceptor(){
PageInterceptor pageInterceptor = new PageInterceptor();
Properties properties = new Properties();
//設(shè)置數(shù)據(jù)庫(kù)類型
properties.setProperty("helperDialect", "MySQL");
//該參數(shù)默認(rèn)為false
//設(shè)置為true時(shí)，會(huì)將RowBounds第一個(gè)參數(shù)offset當(dāng)成pageNum頁碼使用
//和startPage中的pageNum效果一樣
properties.setProperty("offsetAsPageNum", "true");
//該參數(shù)默認(rèn)為false
//設(shè)置為true時(shí)，使用RowBounds分頁會(huì)進(jìn)行count查詢
properties.setProperty("rowBoundsWithCount", "true");
pageInterceptor.setProperties(properties);
return pageInterceptor;
}
@Bean
public SqlSessionFactoryBean sqlSession() {
SqlSessionFactoryBean sqlSession = new SqlSessionFactoryBean();
sqlSession.setDataSource(dataSource());
try {
Resource[] resources = new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml");
sqlSession.setMapperLocations(resources);
//配置PageHelper作為MyBatis的Interceptor，完成分頁操作
PageInterceptor pageInterceptor = this.initPageInterceptor();
//配置自定義的Interceptro作為MyBatis的Interceptor,完成分頁操作
DefinedPageInterceptor definedPageInterceptor = new DefinedPageInterceptor();
sqlSession.setPlugins(new Interceptor[]{pageInterceptor, definedPageInterceptor});
return sqlSession;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}3.mapper依然是查詢所有數(shù)據(jù)
4.為DAO層再封裝一次方法
@Repository
public class PageHelperHandler {
@Autowired
private SqlSessionFactory sqlSessionFactory;
public List findByPageHelper(PageInfo info) {
SqlSession session = sqlSessionFactory.openSession();
PageHelper.startPage(info.getPageNo(), info.getPageSize());
//寫到要使用到的類名和方法名
List users = session.selectList("cn.edu.yau.mapper.UserMapper.selectAll");
return users;
}
} 6.業(yè)務(wù)層直接調(diào)用Handler
7.控制層直接調(diào)用
看完這篇關(guān)于Java如何使用MyBatis框架分頁的文章，如果覺得文章內(nèi)容寫得不錯(cuò)的話，可以把它分享出去給更多人看到。
