Flume高级之自定义MySQLSource

1 自定义Source说明

Source是负责接收数据到Flume Agent的组件。Source组件可以处理各种类型、各种格式的日志数据，包括avro、thrift、exec、jms、spooling directory、netcat、sequence generator、syslog、http、legacy。官方提供的source类型已经很多，但是有时候并不能满足实际开发当中的需求，此时我们就需要根据实际需求自定义某些Source。

如：实时监控MySQL，从MySQL中获取数据传输到HDFS或者其他存储框架，所以此时需要我们自己实现MySQLSource。

官方也提供了自定义source的接口：

官网说明：https://flume.apache.org/FlumeDeveloperGuide.html#source

3 自定义MySQLSource组成

2 自定义MySQLSource步骤

根据官方说明自定义MySqlSource需要继承AbstractSource类并实现Configurable和PollableSource接口。

实现相应方法：

getBackOffSleepIncrement()//暂不用

getMaxBackOffSleepInterval()//暂不用

configure(Context context)//初始化context

process()//获取数据（从MySql获取数据，业务处理比较复杂，所以我们定义一个专门的类——SQLSourceHelper来处理跟MySql的交互），封装成Event并写入Channel，这个方法被循环调用

stop()//关闭相关的资源

4 代码实现

4.1 导入Pom依赖

<dependencies>

    <dependency>

        <groupId>org.apache.flume</groupId>

        <artifactId>flume-ng-core</artifactId>

        <version>1.7.0</version>

    </dependency>

    <dependency>

        <groupId>mysql</groupId>

        <artifactId>mysql-connector-java</artifactId>

        <version>5.1.27</version>

    </dependency>

</dependencies>

4.2 添加配置信息

在ClassPath下添加jdbc.properties和log4j. properties

jdbc.properties:

dbDriver=com.mysql.jdbc.Driver

dbUrl=jdbc:mysql://hadoop102:3306/mysqlsource?useUnicode=true&characterEncoding=utf-8

dbUser=root

dbPassword=000000

log4j. properties:

#--------console-----------

log4j.rootLogger=info,myconsole,myfile

log4j.appender.myconsole=org.apache.log4j.ConsoleAppender

log4j.appender.myconsole.layout=org.apache.log4j.SimpleLayout

#log4j.appender.myconsole.layout.ConversionPattern =%d [%t] %-5p [%c] - %m%n

#log4j.rootLogger=error,myfile

log4j.appender.myfile=org.apache.log4j.DailyRollingFileAppender

log4j.appender.myfile.File=/tmp/flume.log

log4j.appender.myfile.layout=org.apache.log4j.PatternLayout

log4j.appender.myfile.layout.ConversionPattern =%d [%t] %-5p [%c] - %m%n

4.3 SQLSourceHelper

1）属性说明：

属性	说明（括号中为默认值）
runQueryDelay	查询时间间隔（10000）
batchSize	缓存大小（100）
startFrom	查询语句开始id（0）
currentIndex	查询语句当前id，每次查询之前需要查元数据表
recordSixe	查询返回条数
table	监控的表名
columnsToSelect	查询字段（*）
customQuery	用户传入的查询语句
query	查询语句
defaultCharsetResultSet	编码格式（UTF-8）

2）方法说明：

方法	说明
SQLSourceHelper(Context context)	构造方法，初始化属性及获取JDBC连接
InitConnection(String url, String user, String pw)	获取JDBC连接
checkMandatoryProperties()	校验相关属性是否设置（实际开发中可增加内容）
buildQuery()	根据实际情况构建sql语句，返回值String
executeQuery()	执行sql语句的查询操作，返回值List<List<Object>>
getAllRows(List<List<Object>> queryResult)	将查询结果转换为String，方便后续操作
updateOffset2DB(int size)	根据每次查询结果将offset写入元数据表
execSql(String sql)	具体执行sql语句方法
getStatusDBIndex(int startFrom)	获取元数据表中的offset
queryOne(String sql)	获取元数据表中的offset实际sql语句执行方法
close()	关闭资源

3）代码分析

4）代码实现：

import org.apache.flume.Context;

import org.apache.flume.conf.ConfigurationException;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.io.IOException;

import java.sql.*;

import java.text.ParseException;

import java.util.ArrayList;

import java.util.List;

import java.util.Properties;

public class SQLSourceHelper {

    private static final Logger LOG = LoggerFactory.getLogger(SQLSourceHelper.class);

    private int runQueryDelay, //两次查询的时间间隔

            startFrom,            //开始id

            currentIndex,            //当前id

            recordSixe = 0,      //每次查询返回结果的条数

            maxRow;                //每次查询的最大条数

    private String table,       //要操作的表

            columnsToSelect,     //用户传入的查询的列

            customQuery,          //用户传入的查询语句

            query,                 //构建的查询语句

            defaultCharsetResultSet;//编码集

    //上下文，用来获取配置文件

    private Context context;

    //为定义的变量赋值（默认值），可在flume任务的配置文件中修改

    private static final int DEFAULT_QUERY_DELAY = 10000;

    private static final int DEFAULT_START_VALUE = 0;

    private static final int DEFAULT_MAX_ROWS = 2000;

    private static final String DEFAULT_COLUMNS_SELECT = "*";

    private static final String DEFAULT_CHARSET_RESULTSET = "UTF-8";

    private static Connection conn = null;

    private static PreparedStatement ps = null;

    private static String connectionURL, connectionUserName, connectionPassword;

    //加载静态资源

static {

        Properties p = new Properties();

        try {

            p.load(SQLSourceHelper.class.getClassLoader().getResourceAsStream("jdbc.properties"));

            connectionURL = p.getProperty("dbUrl");

            connectionUserName = p.getProperty("dbUser");

            connectionPassword = p.getProperty("dbPassword");

            Class.forName(p.getProperty("dbDriver"));

        } catch (IOException | ClassNotFoundException e) {

            LOG.error(e.toString());

        }

    }

    //获取JDBC连接

    private static Connection InitConnection(String url, String user, String pw) {

        try {

            Connection conn = DriverManager.getConnection(url, user, pw);

            if (conn == null)

                throw new SQLException();

            return conn;

        } catch (SQLException e) {

            e.printStackTrace();

        }

        return null;

    }

    //构造方法

SQLSourceHelper(Context context) throws ParseException {

        //初始化上下文

        this.context = context;

        //有默认值参数：获取flume任务配置文件中的参数，读不到的采用默认值

        this.columnsToSelect = context.getString("columns.to.select", DEFAULT_COLUMNS_SELECT);

        this.runQueryDelay = context.getInteger("run.query.delay", DEFAULT_QUERY_DELAY);

        this.startFrom = context.getInteger("start.from", DEFAULT_START_VALUE);

        this.defaultCharsetResultSet = context.getString("default.charset.resultset", DEFAULT_CHARSET_RESULTSET);

        //无默认值参数：获取flume任务配置文件中的参数

        this.table = context.getString("table");

        this.customQuery = context.getString("custom.query");

        connectionURL = context.getString("connection.url");

        connectionUserName = context.getString("connection.user");

        connectionPassword = context.getString("connection.password");

        conn = InitConnection(connectionURL, connectionUserName, connectionPassword);

        //校验相应的配置信息，如果没有默认值的参数也没赋值，抛出异常

        checkMandatoryProperties();

        //获取当前的id

        currentIndex = getStatusDBIndex(startFrom);

        //构建查询语句

        query = buildQuery();

    }

    //校验相应的配置信息（表，查询语句以及数据库连接的参数）

private void checkMandatoryProperties() {

        if (table == null) {

            throw new ConfigurationException("property table not set");

        }

        if (connectionURL == null) {

            throw new ConfigurationException("connection.url property not set");

        }

        if (connectionUserName == null) {

            throw new ConfigurationException("connection.user property not set");

        }

        if (connectionPassword == null) {

            throw new ConfigurationException("connection.password property not set");

        }

    }

    //构建sql语句

private String buildQuery() {

        String sql = "";

        //获取当前id

        currentIndex = getStatusDBIndex(startFrom);

        LOG.info(currentIndex + "");

        if (customQuery == null) {

            sql = "SELECT " + columnsToSelect + " FROM " + table;

        } else {

            sql = customQuery;

        }

        StringBuilder execSql = new StringBuilder(sql);

        //以id作为offset

        if (!sql.contains("where")) {

            execSql.append(" where ");

            execSql.append("id").append(">").append(currentIndex);

            return execSql.toString();

        } else {

            int length = execSql.toString().length();

            return execSql.toString().substring(0, length - String.valueOf(currentIndex).length()) + currentIndex;

        }

    }

    //执行查询

List<List<Object>> executeQuery() {

        try {

            //每次执行查询时都要重新生成sql，因为id不同

            customQuery = buildQuery();

            //存放结果的集合

            List<List<Object>> results = new ArrayList<>();

            if (ps == null) {

                //

                ps = conn.prepareStatement(customQuery);

            }

            ResultSet result = ps.executeQuery(customQuery);

            while (result.next()) {

                //存放一条数据的集合（多个列）

                List<Object> row = new ArrayList<>();

                //将返回结果放入集合

                for (int i = 1; i <= result.getMetaData().getColumnCount(); i++) {

                    row.add(result.getObject(i));

                }

                results.add(row);

            }

            LOG.info("execSql:" + customQuery + "\nresultSize:" + results.size());

            return results;

        } catch (SQLException e) {

            LOG.error(e.toString());

            // 重新连接

            conn = InitConnection(connectionURL, connectionUserName, connectionPassword);

        }

        return null;

    }

    //将结果集转化为字符串，每一条数据是一个list集合，将每一个小的list集合转化为字符串

List<String> getAllRows(List<List<Object>> queryResult) {

        List<String> allRows = new ArrayList<>();

        if (queryResult == null || queryResult.isEmpty())

            return allRows;

        StringBuilder row = new StringBuilder();

        for (List<Object> rawRow : queryResult) {

            Object value = null;

            for (Object aRawRow : rawRow) {

                value = aRawRow;

                if (value == null) {

                    row.append(",");

                } else {

                    row.append(aRawRow.toString()).append(",");

                }

            }

            allRows.add(row.toString());

            row = new StringBuilder();

        }

        return allRows;

    }

    //更新offset元数据状态，每次返回结果集后调用。必须记录每次查询的offset值，为程序中断续跑数据时使用，以id为offset

    void updateOffset2DB(int size) {

        //以source_tab做为KEY，如果不存在则插入，存在则更新（每个源表对应一条记录）

        String sql = "insert into flume_meta(source_tab,currentIndex) VALUES('"

                + this.table

                + "','" + (recordSixe += size)

                + "') on DUPLICATE key update source_tab=values(source_tab),currentIndex=values(currentIndex)";

        LOG.info("updateStatus Sql:" + sql);

        execSql(sql);

    }

    //执行sql语句

private void execSql(String sql) {

        try {

            ps = conn.prepareStatement(sql);

            LOG.info("exec::" + sql);

            ps.execute();

        } catch (SQLException e) {

            e.printStackTrace();

        }

    }

    //获取当前id的offset

private Integer getStatusDBIndex(int startFrom) {

        //从flume_meta表中查询出当前的id是多少

        String dbIndex = queryOne("select currentIndex from flume_meta where source_tab='" + table + "'");

        if (dbIndex != null) {

            return Integer.parseInt(dbIndex);

        }

        //如果没有数据，则说明是第一次查询或者数据表中还没有存入数据，返回最初传入的值

        return startFrom;

    }

    //查询一条数据的执行语句(当前id)

private String queryOne(String sql) {

        ResultSet result = null;

        try {

            ps = conn.prepareStatement(sql);

            result = ps.executeQuery();

            while (result.next()) {

                return result.getString(1);

            }

        } catch (SQLException e) {

            e.printStackTrace();

        }

        return null;

    }

    //关闭相关资源

void close() {

        try {

            ps.close();

            conn.close();

        } catch (SQLException e) {

            e.printStackTrace();

        }

    }

    int getCurrentIndex() {

        return currentIndex;

    }

    void setCurrentIndex(int newValue) {

        currentIndex = newValue;

    }

    int getRunQueryDelay() {

        return runQueryDelay;

    }

    String getQuery() {

        return query;

    }

    String getConnectionURL() {

        return connectionURL;

    }

    private boolean isCustomQuerySet() {

        return (customQuery != null);

    }

    Context getContext() {

        return context;

    }

    public String getConnectionUserName() {

        return connectionUserName;

    }

    public String getConnectionPassword() {

        return connectionPassword;

    }

    String getDefaultCharsetResultSet() {

        return defaultCharsetResultSet;

    }

}

4.4 MySQLSource

代码实现：

import org.apache.flume.Context;

import org.apache.flume.Event;

import org.apache.flume.EventDeliveryException;

import org.apache.flume.PollableSource;

import org.apache.flume.conf.Configurable;

import org.apache.flume.event.SimpleEvent;

import org.apache.flume.source.AbstractSource;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.text.ParseException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

public class SQLSource extends AbstractSource implements Configurable, PollableSource {

    //打印日志

private static final Logger LOG = LoggerFactory.getLogger(SQLSource.class);

    //定义sqlHelper

    private SQLSourceHelper sqlSourceHelper;

    @Override

    public long getBackOffSleepIncrement() {

        return 0;

    }

    @Override

    public long getMaxBackOffSleepInterval() {

        return 0;

    }

    @Override

public void configure(Context context) {

        try {

            //初始化

            sqlSourceHelper = new SQLSourceHelper(context);

        } catch (ParseException e) {

            e.printStackTrace();

        }

    }

    @Override

public Status process() throws EventDeliveryException {

        try {

            //查询数据表

            List<List<Object>> result = sqlSourceHelper.executeQuery();

            //存放event的集合

            List<Event> events = new ArrayList<>();

            //存放event头集合

            HashMap<String, String> header = new HashMap<>();

            //如果有返回数据，则将数据封装为event

            if (!result.isEmpty()) {

                List<String> allRows = sqlSourceHelper.getAllRows(result);

                Event event = null;

                for (String row : allRows) {

                    event = new SimpleEvent();

                    event.setBody(row.getBytes());

                    event.setHeaders(header);

                    events.add(event);

                }

                //将event写入channel

                this.getChannelProcessor().processEventBatch(events);

                //更新数据表中的offset信息

                sqlSourceHelper.updateOffset2DB(result.size());

            }

            //等待时长

            Thread.sleep(sqlSourceHelper.getRunQueryDelay());

            return Status.READY;

        } catch (InterruptedException e) {

            LOG.error("Error procesing row", e);

            return Status.BACKOFF;

        }

    }

    @Override

public synchronized void stop() {

        LOG.info("Stopping sql source {} ...", getName());

        try {

            //关闭资源

            sqlSourceHelper.close();

        } finally {

            super.stop();

        }

    }

}

5 测试

5.1 Jar包准备

1) 将MySql驱动包放入Flume的lib目录下

[FLY@hadoop102 flume]$ cp \

/opt/sorfware/mysql-libs/mysql-connector-java-5.1.27/mysql-connector-java-5.1.27-bin.jar \

/opt/module/flume/lib/

2) 打包项目并将Jar包放入Flume的lib目录下

5.5.2 配置文件准备

1）创建配置文件并打开

[FLY@hadoop102 job]$ touch mysql.conf

[FLY@hadoop102 job]$ vim mysql.conf

2）添加如下内容

# Name the components on this agent

a1.sources = r1

a1.sinks = k1

a1.channels = c1

# Describe/configure the source

a1.sources.r1.type = com.FLY.source.SQLSource

a1.sources.r1.connection.url = jdbc:mysql://192.168.9.102:3306/mysqlsource

a1.sources.r1.connection.user = root

a1.sources.r1.connection.password = 000000

a1.sources.r1.table = student

a1.sources.r1.columns.to.select = *

#a1.sources.r1.incremental.column.name = id

#a1.sources.r1.incremental.value = 0

a1.sources.r1.run.query.delay=5000

# Describe the sink

a1.sinks.k1.type = logger

# Describe the channel

a1.channels.c1.type = memory

a1.channels.c1.capacity = 1000

a1.channels.c1.transactionCapacity = 100

# Bind the source and sink to the channel

a1.sources.r1.channels = c1

a1.sinks.k1.channel = c1

5.5.3 MySql表准备

1) 创建MySqlSource数据库

CREATE DATABASE mysqlsource；

2) 在MySqlSource数据库下创建数据表Student和元数据表Flume_meta

CREATE TABLE `student` (

`id` int() NOT NULL AUTO_INCREMENT,

`name` varchar() NOT NULL,

PRIMARY KEY (`id`)

);

CREATE TABLE `flume_meta` (

`source_tab` varchar() NOT NULL,

`currentIndex` varchar() NOT NULL,

PRIMARY KEY (`source_tab`)

);

3) 向数据表中添加数据

1 zhangsan

2 lisi

3 wangwu

4 zhaoliu

5.5.4 测试并查看结果

1) 任务执行

[FLY@hadoop102 flume]$ bin/flume-ng agent --conf conf/ --name a1 \

--conf-file job/mysql.conf -Dflume.root.logger=INFO,console

1) 结果展示，如图6-2所示：

巴特西