详解MyBatis如何在大数据量下使用流式查询进行数据同步

int page = 1;
int pageNum = 1000;
while (true){
    UserQueryRequest request = new UserQueryRequest();
    request.setPage(page);
    request.setPageSize(pageNum);
    PageInfo<User> pageInfo = userMapper.getUserPage(request);
    if (CollectionUtils.isEmpty(pageInfo.getList()) ){
        break;
    }
    List<User> userList = pageInfo.getList();
    // 具体的处理逻辑 省略
    page ++;
}

<select id="selectUsers" resultType="User" fetchSize="1000">
   SELECT userId from t_user
 </select>

import lombok.extern.slf4j.Slf4j;
import model.User;
import org.apache.ibatis.session.ResultContext;
import org.apache.ibatis.session.ResultHandler;
import java.util.ArrayList;
import java.util.List;

/**
 * @author: jie
 * @create: 2023/3/29 16:51
 * @description:
 */
@Slf4j
public class SyncDataHandler implements ResultHandler<User> {

    /**
     * 每批处理数量
     */
    private final static int BATCH_SIZE = 1000;

    /**
     * 缓存数据
     */
    private List<User> cacheList = new ArrayList<>();

    /**
     * 同步熟虑
     */
    private int total = 0;


    @Override
    public void handleResult(ResultContext<? extends User> resultContext) {
        User coreInfoCyDTO =  resultContext.getResultObject();
        this.cacheList.add(coreInfoCyDTO);
        //每到达BATCH_SIZE 条数据处理一次
        if (this.cacheList.size() >= BATCH_SIZE) {
            this.handle();
        }
        total++;
    }


    /**
     * 处理缓存数据
     */
    private void handle() {
        try {
            // 具体的处理逻辑 省略
        } finally {
            // 清除处理过的缓存数据
            this.cacheList.clear();
        }
    }

    /**
     * 处理最后一批没有进行处理的数据
     */
    public int end() {
        this.end();
        return total;
    }
}

SyncDataHandler syncDataHandler = new SyncDataHandler();
userMapper.getUserList("selectUsers", syncDataHandler);
syncDataHandler.end();