MyBatis:自定义分页插件

一、mapper

    
        select  * from country
    

二、接口：

    List selectCountry3(RowBounds rowBounds);

三、插件定义：

package cn.edu.tju.config;

import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

import java.util.Properties;

@Intercepts({
        @Signature(type = Executor.class, method = "query", args = {
                MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class
        }),
        @Signature(type = Executor.class, method = "query", args = {
                MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class
        })

})
public class MyPageInterceptor implements Interceptor {
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        Object[] args = invocation.getArgs();

        MappedStatement ms = (MappedStatement) args[0];
        BoundSql boundSql = ms.getBoundSql(args[1]);
        RowBounds rowBounds = (RowBounds) args[2];

        String sql = boundSql.getSql();
        sql += " limit ";

        int offset = rowBounds.getOffset();
        int limit = rowBounds.getLimit();
        sql += (offset-1)*limit;
        sql += ",";
        sql += limit;
        System.out.println(sql);

        BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), sql,
                boundSql.getParameterMappings(), boundSql.getParameterObject());



        Executor executor = (Executor) invocation.getTarget();
        return executor.query(ms, args[1], (RowBounds) args[2], (ResultHandler) args[3], null, newBoundSql);
    }

    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target,this);
    }

    @Override
    public void setProperties(Properties properties) {

    }
}

四、插件注册：

五、查询：

package cn.edu.tju.test;

import cn.edu.tju.domain.Country;
import cn.edu.tju.mapper.PersonMapper;
import com.github.pagehelper.PageHelper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.util.List;

public class MyBatisTest11 {
    public static void main(String[] args) throws IOException {
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(

                Resources.getResourceAsStream("mybatis-config.xml"));


        SqlSession sqlSession = sqlSessionFactory.openSession();
        List countries = sqlSession.getMapper(PersonMapper.class)
                .selectCountry3(new RowBounds(1, 2));
        System.out.println(countries.size());
        System.out.println(countries);
    }
}