我要评论本文为大家分享了java使用mybatis框架分页的五种方式，供大家参考，具体内容如下
初始准备
1.创建分页对象类，方便模块间传值
//pageinfo.java
import lombok.data;
@data
public class pageinfo {
private int pageno;
private int pagesize;
}
2.定义dao层接口
import org.apache.ibatis.session.rowbounds;
import org.springframework.stereotype.repository;
import java.util.list;
@repository
public interface usermapper {
user selectbyuser(user user);
list<user> selectall();
list<user> selectbypageinfo(pageinfo info);
list<user> selectbyinterceptor(pageinfo info);
list<user> selectbyrowbounds(rowbounds rowbounds);
}
3.mapper中定义结果集合baseresult
<resultmap id="baseresult" type="cn.edu.yau.pojo.user"> <id property="id" column="id" jdbctype="integer"></id> <result property="username" column="username" jdbctype="varchar"></result> <result property="password" column="password" jdbctype="varchar"></result> </resultmap>
一、原始切分：最原始方法，不建议使用
1.mapper代码:查询所有数据
<select id="selectall" resultmap="baseresult"> select * from tb_user </select>
2.业务层代码:利用list的sublist()方法对数据进行切片
public list<user> findbyall(pageinfo info) {
list<user> users = usermapper.selectall();
return users.sublist(info.getpageno(), info.getpagesize());
}
3.控制层代码
@requestmapping(value = "/userlist_1", method = requestmethod.get)
@responsebody
public result finduserbysublist(pageinfo info) {
list<user> users = userservice.findbyall(info);
if(users.size() == 0) {
return resultgenerator.genfailresult("未查找到用户");
}
return resultgenerator.gensuccessresult(users);
}
二、limit关键字
1.mapper代码:利用limit关键字实现分页
<select id="selectbypageinfo" resultmap="baseresult">
select * from tb_user limit #{pageno}, #{pagesize}
</select>
2.业务层直接调用
public list<user> findbypageinfo(pageinfo info) {
return usermapper.selectbypageinfo(info);
}
3.控制层直接调用
三、rowbounds实现分页
1.在dao层定义好所要传输的分页信息，类型为rowbounds
2.mapper层：查询所有数据
3.业务层：将pageinfo信息封装成rowbounds,调用dao层方法
public list<user> findbyrowbounds(pageinfo info) {
return usermapper.selectbyrowbounds(new rowbounds(info.getpageno(), info.getpagesize()));
}
4.控制层直接调用
四、mybatis的interceptor实现:实现复杂，需要明白mybatis的实现
1.创建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拦截器进行分页
*
* @intercepts 说明是一个拦截器
* @signature 拦截器的签名
* type 拦截的类型 四大对象之一( executor,resultsethandler,parameterhandler,statementhandler)
* method 拦截的方法
* args 参数,高版本需要加个integer.class参数,不然会报错
*
*/
@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 {
//获取statementhandler,默认的是routingstatementhandler
statementhandler statementhandler = (statementhandler) invocation.gettarget();
//获取statementhandler的包装类
metaobject metaobject = systemmetaobject.forobject(statementhandler);
//分隔代理对象
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);
}
//获取查看接口映射的相关信息
mappedstatement mappedstatement = (mappedstatement) metaobject.getvalue("delegate.mappedstatement");
string mapid = mappedstatement.getid();
//拦截以byinterceptor结尾的请求，统一实现分页
if (mapid.matches(".+byinterceptor$")) {
system.out.println("log:已触发分页拦截器");
//获取进行数据库操作时管理参数的handler
parameterhandler parameterhandler = (parameterhandler) metaobject.getvalue("delegate.parameterhandler");
//获取请求时的参数
pageinfo info = (pageinfo) parameterhandler.getparameterobject();
//获取原始sql语句
string originalsql = (string) metaobject.getvalue("delegate.boundsql.sql");
//构建分页功能的sql语句
string sql = originalsql.trim() + " limit " + info.getpageno() + ", " + info.getpagesize();
metaobject.setvalue("delegate.boundsql.sql", sql);
}
//调用原对象方法，进入责任链下一级
return invocation.proceed();
}
@override
public object plugin(object target) {
//生成object对象的动态代理对象
return plugin.wrap(target, this);
}
@override
public void setproperties(properties properties) {
//如果分页每页数量是统一的，可以在这里进行统一配置，也就无需再传入pageinfo信息了
}
}
2.将interceptor添加至mybatisconfig中，这里采用javaconfig的方式
@bean
public sqlsessionfactorybean sqlsession() {
sqlsessionfactorybean sqlsession = new sqlsessionfactorybean();
sqlsession.setdatasource(datasource());
try {
resource[] resources = new pathmatchingresourcepatternresolver().getresources("classpath:mapper/*.xml");
sqlsession.setmapperlocations(resources);
//配置自定义的interceptro作为mybatis的interceptor,完成分页操作
definedpageinterceptor definedpageinterceptor = new definedpageinterceptor();
sqlsession.setplugins(new interceptor[]{definedpageinterceptor});
return sqlsession;
} catch (ioexception e) {
e.printstacktrace();
}
return null;
}
3.dao层接口方法名需要和代码中自定义的".+byinterceptor$"正则表达式相匹配,mapper的书写依然是查询所有数据
<select id="selectbyinterceptor" resultmap="baseresult"> select * from tb_user </select>
4.业务层直接调用
5.控制层直接调用
五、开源项目pagehelper实现：本质还是自己封装了个interceptor
1.引入pagehelper的jar包
<dependency> <groupid>com.github.pagehelper</groupid> <artifactid>pagehelper</artifactid> <version>5.1.10</version> </dependency>
2.配置pageinterceptor
public pageinterceptor initpageinterceptor(){
pageinterceptor pageinterceptor = new pageinterceptor();
properties properties = new properties();
//设置数据库类型
properties.setproperty("helperdialect", "mysql");
//该参数默认为false
//设置为true时，会将rowbounds第一个参数offset当成pagenum页码使用
//和startpage中的pagenum效果一样
properties.setproperty("offsetaspagenum", "true");
//该参数默认为false
//设置为true时，使用rowbounds分页会进行count查询
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作为mybatis的interceptor，完成分页操作
pageinterceptor pageinterceptor = this.initpageinterceptor();
//配置自定义的interceptro作为mybatis的interceptor,完成分页操作
definedpageinterceptor definedpageinterceptor = new definedpageinterceptor();
sqlsession.setplugins(new interceptor[]{pageinterceptor, definedpageinterceptor});
return sqlsession;
} catch (ioexception e) {
e.printstacktrace();
}
return null;
}
3.mapper依然是查询所有数据
4.为dao层再封装一次方法
@repository
public class pagehelperhandler {
@autowired
private sqlsessionfactory sqlsessionfactory;
public list<user> findbypagehelper(pageinfo info) {
sqlsession session = sqlsessionfactory.opensession();
pagehelper.startpage(info.getpageno(), info.getpagesize());
//写到要使用到的类名和方法名
list<user> users = session.selectlist("cn.edu.yau.mapper.usermapper.selectall");
return users;
}
}
6.业务层直接调用handler
7.控制层直接调用
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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