时间序列数据库KDB 与Java结合使用介绍 -- 2 基于KDB Java的写入实现

这一篇说说一个简单的写入实现，首先创建对应的KDB Server Connection，这里给出一个类似singleton的实现，加入了connection挂掉了重连的功能，没有考虑短时间重连太多被封的可能性，原因是因为我们的系统中由单一线程每五秒钟往kdb写数一次，ip在kdb的白名单中，所以没可能会被封。

/**
 *
 */
package kx;

import java.io.IOException;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

import kx.C.KException;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.log4j.Log4j2;

/**
 * @author cloudlu
 *
 */
@Log4j2
@Getter
@Setter
public class KDBConnectionManager {

    @NotNull
    @Size(min = 2, max = 30)
    private String host;
    @NotNull
    private int port;
    @NotNull
    @Size(min = 2, max = 30)
    private String username;
    @NotNull
    @Size(min = 2, max = 30)
    private String password;

    private C c;

    private boolean isValid(final C conn) {
        if (null == conn)
            return false;
        if (null == conn.s || conn.s.isClosed() || !conn.s.isConnected())
            return false;
        try {
            conn.k("");
        } catch (final Exception e) {
            return false;
        }
        return true;
    }

    public final C get() {
        if (isValid(c))
            return c;
        synchronized (this) {
            // double check
            if (isValid(c))
                return c;
            try {
                c = new C(host, port, username + ":" + password);
            } catch (KException | IOException e) {
                LOG.error("fail to create connection to host {} port {}", host,
                        port, e);
            }
        }
        return c;
    }

    public void release(final C con) {

    }
}

接下来编写KDBData类，负责把业务对象映射到KDB表。不同KDB表应该有不同的KDBData类。以KDB自带的例子为例：

package kx;

import java.sql.Time;

import lombok.Data;

@Data
public class KDBData {

    public static final String TABLE_NAME = "test";

    public static final String[] COL_NAMES = new String[] { "time", "sym",
        "price", "size", "stop", "cond", "ex" };

    private Time time;
    private String sym;
    private double price;
    private int size;
    private boolean stop;
    private char cond;
    private char ex;
}

最后是最主要的KDBService，负责往kdb里面插入数据：

/**
 *
 */
package kx;

import java.io.IOException;
import java.util.Collection;

import kx.C.KException;
import lombok.extern.log4j.Log4j2;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

/**
 * @author cloudlu
 *
 */
@Log4j2
@Service
public class KDBService {

    @Autowired
    @Qualifier("ticketPlant")
    private KDBConnectionManager manager;

    /**
     * insert data to specified table
     *
     * @param data
     *            : data with key - value from external system
     * @return
     */
    public boolean insertKDBData(final Collection data) {
        final C con = manager.get();
        final Object[] tab = convertData(data);
        final Object[] updStatement = { ".u.upd", KDBData.TABLE_NAME, tab };
        try {
            final Object result = con.k(updStatement);
            if (null == result)
                return true;
        } catch (KException | IOException e) {
            LOG.error(e);
        } finally {
            manager.release(con);
        }
        return false;
    }

    /**
     * need to convert object to data for column based storage
     *
     * @param cols
     * @param data
     * @return
     */
    private Object[] convertData(final Collection data) {
        final Object[] cols = KDBData.COL_NAMES;
        final Object[][] result = new Object[cols.length][data.size()];
        int i = 0;
        for (final KDBData singleData : data) {
            result[0][i] = singleData.getTime();
            result[1][i] = singleData.getSym();
            result[2][i] = singleData.getPrice();
            result[3][i] = singleData.getSize();
            result[4][i] = singleData.isStop();
            result[5][i] = singleData.getCond();
            result[6][i] = singleData.getEx();
            i++;
        }
        return result;
    }
}