db-data-to-csv/src/main/java/com/vcarecity/cvs/service/impl/AbstractSQLQueryService.java

package com.vcarecity.cvs.service.impl;

import com.vcarecity.cvs.core.AutoMapper;
import com.vcarecity.cvs.service.SQLQueryService;
import com.zaxxer.hikari.HikariDataSource;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import static com.vcarecity.cvs.FileExporterApp.TABLE_COLUMN;

/**
 * @author Kerry on 19/11/27
 */

@Slf4j
public abstract class AbstractSQLQueryService implements SQLQueryService {

    private boolean isFirst = true;


    protected final HikariDataSource dataSource;

    protected AbstractSQLQueryService(HikariDataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Override
    public <T> List<T> queryByPage(String table, int page, int pageCount, Class<T> clazz) throws SQLException {

        final String querySql = getQuerySql(table);

        long startTime = System.currentTimeMillis();


        final Connection connection = dataSource.getConnection();

        final PreparedStatement preparedStatement = getPreparedStatement(connection, querySql, page, pageCount);

        ResultSet resultSet = preparedStatement.executeQuery();

        List<T> list = resultMapper(table, resultSet, clazz);

        logger.debug("query success. size = {}. usageTime = {} /ms", list.size(), (System.currentTimeMillis() - startTime));

        resultSet.close();
        preparedStatement.close();
        connection.close();

        return list;
    }

    /**
     * 组装表
     *
     * @param table
     * @return
     */
    protected abstract String getQuerySql(String table);

    /**
     * get PreparedStatement
     *
     * @param connection
     * @param sql
     * @param start
     * @param pageCount
     * @return
     * @throws SQLException
     */
    protected abstract PreparedStatement getPreparedStatement(Connection connection, String sql, int start, int pageCount) throws SQLException;

    public <T> List<T> resultMapper(String table, ResultSet resultSet, Class<T> clazz) throws SQLException {
        if (clazz == Object.class) {
            //noinspection unchecked
            return (List<T>) resultSetToObject(table, resultSet);
        }
        return autoMapper(resultSet, clazz);
    }

    public List<Object[]> resultSetToObject(String table, ResultSet resultSet) throws SQLException {
        final ResultSetMetaData metaData = resultSet.getMetaData();
        final int columnCount = metaData.getColumnCount() - 1;


        final List<ColumnIndexName> columnWithObject = getColumnWithObject(metaData);
        final Set<Integer> skipIndex = columnWithObject.stream().map(ColumnIndexName::getIndex).collect(Collectors.toSet());

        final String[] header = columnWithObject.stream().map(ColumnIndexName::getName).toArray(String[]::new);


        TABLE_COLUMN.put(table, header);


        if (isFirst) {
            final String join = String.join(",", header);
            logger.info("header = ({})", join);
            isFirst = false;
        }

        List<Object[]> data = new ArrayList<>();
        while (resultSet.next()) {
            Object[] objects = new Object[columnCount];
            int cIndex = 0;
            for (int i = 0; i < columnCount; i++) {
                if (!skipIndex.contains(i)) {
                    continue;
                }
                objects[cIndex++] = resultSet.getObject(i + 1);
            }
            data.add(objects);
        }
        return data;
    }


    @NoArgsConstructor
    @AllArgsConstructor
    @Data
    public static class ColumnIndexName {
        private int index;
        private String name;
    }

    /**
     * @param metaData
     * @return
     */
    protected List<ColumnIndexName> getColumnWithObject(ResultSetMetaData metaData) throws SQLException {
        final int columnCount = metaData.getColumnCount();
        List<ColumnIndexName> res = new ArrayList<>(columnCount);
        for (int i = 0; i < columnCount; i++) {
            String name = metaData.getColumnName(i + 1);
            res.add(new ColumnIndexName(i, name));
        }
        return res;
    }

    public <T> List<T> autoMapper(ResultSet resultSet, Class<T> clazz) throws SQLException {
        List<T> list = new ArrayList<>();
        while (resultSet.next()) {
            final T t = AutoMapper.autoMapper(resultSet, clazz);
            if (t != null) {
                list.add(t);
            }
        }
        return list;
    }

}