db-data-to-csv/src/main/java/com/vcarecity/cvs/starter/SQLStarter.java

package com.vcarecity.cvs.starter;

import com.vcarecity.cvs.factory.ResultHandlerFactory;
import com.vcarecity.cvs.service.ResultHandlerService;
import com.vcarecity.cvs.service.SQLQueryService;
import com.vcarecity.cvs.service.impl.CSVResultHandlerServiceImpl;
import lombok.extern.slf4j.Slf4j;

import javax.inject.Inject;
import java.util.List;

/**
 * @author Kerry on 19/11/20
 */

@Slf4j
public class SQLStarter {

    private static final int PAGE_COUNT = 10000;

    private int pageCount = PAGE_COUNT;

    private final SQLQueryService queryService;
    private final ResultHandlerFactory resultHandlerFactory;

    @Inject
    public SQLStarter(SQLQueryService queryService,
                      ResultHandlerFactory resultHandlerFactory) {
        this.queryService = queryService;
        this.resultHandlerFactory = resultHandlerFactory;
    }

    public void setPageCount(int pageCount) {
        this.pageCount = pageCount;
    }

    /**
     * 导出数据
     *
     * @param table
     * @param properties
     * @throws Exception
     */
    public <T> void exportData(String table, String properties, Class<T> cls) throws Exception {

        if (cls == null) {
            //noinspection unchecked
            cls = (Class<T>) Object.class;
        }
        ResultHandlerService resultHandler = resultHandlerFactory.createResultHandler(properties);


        logger.info("start query database table = {}, file = {}, class = {}", table, properties, cls);

        long startTime = System.currentTimeMillis();

        int currentSize;
        int page = 1;

        do {
            List<T> result = queryService.queryByPage(table, page, this.pageCount, cls);
            resultHandler.resultHandler(result);
            currentSize = result.size();

            page++;

        } while (currentSize == this.pageCount);

        if (resultHandler instanceof CSVResultHandlerServiceImpl) {
            ((CSVResultHandlerServiceImpl) resultHandler).close();
        }

        logger.info("stop query database...{} /ms.", (System.currentTimeMillis() - startTime));
    }

}