文章目录
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
2. 自定义 MysqlSource 组成
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()//暂不用扫描二维码关注公众号，回复： 12653865 查看本文章
-
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.xml 依赖
<dependency>
<groupId>org.apache.flume</groupId>
<artifactId>flume-ng-core</artifactId>
<version>1.9.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
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/gmall?useUnicode=true&characterEncoding=utf-8
dbUser=root
dbPassword=123456
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
-
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） -
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> getAllRows(List<List> 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 -
代码分析：
-
代码实现：
package com.big.data.flume.source; 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：
package com.big.data.flume.source;
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 MySQLSource extends AbstractSource implements Configurable, PollableSource {
//打印日志
private static final Logger LOG = LoggerFactory.getLogger(MySQLSource.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
-
将 Mysql 驱动包放入Flume 的 lib 目录下
[dwjf321@hadoop102 flume]$ cp /opt/sorfware/mysql-connector-java-5.1.47.jar /opt/module/flume/lib/ -
打包项目并将 Jar 包放入 Flume 的lib目录下
5.2 配置文件准备
-
创建配置文件
[dwjf321@hadoop102 conf]$ vim mysql.conf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.dwjf321.source.SQLSource a1.sources.r1.connection.url = jdbc:mysql://hadoop102:3306/gmall a1.sources.r1.connection.user = root a1.sources.r1.connection.password = 123456 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
5.3 MySql 表准备
-
创建 gmall 数据库
-
在 gmall 数据库下创建数据表
student和元数据表flume_metaCREATE TABLE `student` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, PRIMARY KEY (`id`) ); CREATE TABLE `flume_meta` ( `source_tab` varchar(255) NOT NULL, `currentIndex` varchar(255) NOT NULL, PRIMARY KEY (`source_tab`) ); -
向数据表中添加数据
insert into student (name) values ('张三'); insert into student (name) values ('王五'); insert into student (name) values ('李四'); insert into student (name) values ('赵二'); insert into student (name) values ('陆七');
5.4 测试并查看结果
任务执行
[dwjf321@hadoop102 flume]$ bin/flume-ng agent --conf conf/ --name a1 \
--conf-file conf/mysql.conf -Dflume.root.logger=INFO,console