Chapter 102. MyBatis Since Camel 2.7 Both producer and consumer are supported The MyBatis component allows you to query, poll, insert, update and delete data in a relational database using MyBatis . 102.1. Dependencies When using mybatis with Red Hat build of Camel Spring Boot make sure to use the following Maven dependency to have support for auto configuration: <dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-mybatis-starter</artifactId> </dependency> 102.2. URI format Where statementName is the statement name in the MyBatis XML mapping file which maps to the query, insert, update or delete operation you choose to evaluate. You can append query options to the URI in the following format, ?option=value&option=value&... This component will by default load the MyBatis SqlMapConfig file from the root of the classpath with the expected name of SqlMapConfig.xml . If the file is located in another location, you will need to configure the configurationUri option on the MyBatisComponent component. 102.3. Configuring Options Camel components are configured on two separate levels: component level endpoint level 102.3.1. Configuring Component Options The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth. Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all. Configuring components can be done with the Component DSL , in a configuration file (application.properties|yaml), or directly with Java code. 102.3.2. Configuring Endpoint Options Endpoints have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both. Configuring endpoints is done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java. Use Property Placeholders to configure options that allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse. The following two sections lists all the options, firstly for the component followed by the endpoint. 102.4. Component Options The MyBatis component supports 5 options, which are listed below. Name Description Default Type configurationUri (common) Location of MyBatis xml configuration file. The default value is: SqlMapConfig.xml loaded from the classpath. SqlMapConfig.xml String bridgeErrorHandler (consumer) Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false boolean lazyStartProducer (producer) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false boolean autowiredEnabled (advanced) Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. true boolean sqlSessionFactory (advanced) To use the SqlSessionFactory. SqlSessionFactory 102.5. Endpoint Options The MyBatis endpoint is configured using URI syntax: Following are the path and query parameters. 102.5.1. Path Parameters (1 parameters) Name Description Default Type statement (common) Required The statement name in the MyBatis XML mapping file which maps to the query, insert, update or delete operation you wish to evaluate. String 102.5.2. Query Parameters (30 parameters) Name Description Default Type maxMessagesPerPoll (consumer) This option is intended to split results returned by the database pool into the batches and deliver them in multiple exchanges. This integer defines the maximum messages to deliver in single exchange. By default, no maximum is set. Can be used to set a limit of e.g. 1000 to avoid when starting up the server that there are thousands of files. Set a value of 0 or negative to disable it. 0 int onConsume (consumer) Statement to run after data has been processed in the route. String routeEmptyResultSet (consumer) Whether allow empty resultset to be routed to the hop. false boolean sendEmptyMessageWhenIdle (consumer) If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead. false boolean transacted (consumer) Enables or disables transaction. If enabled then if processing an exchange failed then the consumer breaks out processing any further exchanges to cause a rollback eager. false boolean useIterator (consumer) Process resultset individually or as a list. true boolean bridgeErrorHandler (consumer (advanced)) Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false boolean exceptionHandler (consumer (advanced)) To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. ExceptionHandler exchangePattern (consumer (advanced)) Sets the exchange pattern when the consumer creates an exchange. Enum values: * InOnly * InOut * InOptionalOut ExchangePattern pollStrategy (consumer (advanced)) A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel. PollingConsumerPollStrategy processingStrategy (consumer (advanced)) To use a custom MyBatisProcessingStrategy. MyBatisProcessingStrategy executorType (producer) The executor type to be used while executing statements. simple - executor does nothing special. reuse - executor reuses prepared statements. batch - executor reuses statements and batches updates. Enum values: * SIMPLE * REUSE * BATCH SIMPLE ExecutorType inputHeader (producer) User the header value for input parameters instead of the message body. By default, inputHeader == null and the input parameters are taken from the message body. If outputHeader is set, the value is used and query parameters will be taken from the header instead of the body. String outputHeader (producer) Store the query result in a header instead of the message body. By default, outputHeader == null and the query result is stored in the message body, any existing content in the message body is discarded. If outputHeader is set, the value is used as the name of the header to store the query result and the original message body is preserved. Setting outputHeader will also omit populating the default CamelMyBatisResult header since it would be the same as outputHeader all the time. String statementType (producer) Mandatory to specify for the producer to control which kind of operation to invoke. Enum values: * SelectOne * SelectList * Insert * InsertList * Update * UpdateList * Delete * DeleteList StatementType lazyStartProducer (producer (advanced)) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false boolean backoffErrorThreshold (scheduler) The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in. int backoffIdleThreshold (scheduler) The number of subsequent idle polls that should happen before the backoffMultipler should kick-in. int backoffMultiplier (scheduler) To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured. int delay (scheduler) Milliseconds before the poll. 500 long greedy (scheduler) If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the run polled 1 or more messages. false boolean initialDelay (scheduler) Milliseconds before the first poll starts. 1000 long repeatCount (scheduler) Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever. 0 long runLoggingLevel (scheduler) The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that. Enum values: * TRACE * DEBUG * INFO * WARN * ERROR * OFF TRACE LoggingLevel scheduledExecutorService (scheduler) Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool. ScheduledExecutorService scheduler (scheduler) To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler. none Object schedulerProperties (scheduler) To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler. Map startScheduler (scheduler) Whether the scheduler should be auto started. true boolean timeUnit (scheduler) Time unit for initialDelay and delay options. Enum values: * NANOSECONDS * MICROSECONDS * MILLISECONDS * SECONDS * MINUTES * HOURS * DAYS MILLISECONDS TimeUnit useFixedDelay (scheduler) Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details. true boolean 102.6. Message Headers The MyBatis component supports 2 message headers that are listed below. Name Description Default Type CamelMyBatisResult (producer) Constant: MYBATIS_RESULT The response returned from MtBatis in any of the operations. For instance an INSERT could return the auto-generated key, or number of rows etc. Object CamelMyBatisStatementName (common) Constant: MYBATIS_STATEMENT_NAME The statementName used (for example: insertAccount). String 102.7. Message Body The response from MyBatis will only be set as the body if it is a SELECT statement. For example, for INSERT statements Camel will not replace the body. This allows you to continue routing and keep the original body. The response from MyBatis is always stored in the header with the key CamelMyBatisResult . 102.8. Samples For example if you wish to consume beans from a JMS queue and insert them into a database you could do the following: from("activemq:queue:newAccount") .to("mybatis:insertAccount?statementType=Insert"); You must specify the statementType as you need to instruct Camel which kind of operation to invoke. Where insertAccount is the MyBatis ID in the SQL mapping file: <!-- Insert example, using the Account parameter class --> <insert id="insertAccount" parameterType="Account"> insert into ACCOUNT ( ACC_ID, ACC_FIRST_NAME, ACC_LAST_NAME, ACC_EMAIL ) values ( #{id}, #{firstName}, #{lastName}, #{emailAddress} ) </insert> 102.9. Using StatementType for better control of MyBatis When routing to an MyBatis endpoint you will want more fine grained control so you can control whether the SQL statement to be executed is a SELECT , UPDATE , DELETE or INSERT etc. So for instance if we want to route to an MyBatis endpoint in which the IN body contains parameters to a SELECT statement we can do: In the code above we can invoke the MyBatis statement selectAccountById and the IN body should contain the account id we want to retrieve, such as an Integer type. You can do the same for some of the other operations, such as SelectList : And the same for UPDATE , where you can send an Account object as the IN body to MyBatis: 102.9.1. Using InsertList StatementType MyBatis allows you to insert multiple rows using its for-each batch driver. To use this, you need to use the <foreach> in the mapper XML file. For example as shown below: Then you can insert multiple rows, by sending a Camel message to the mybatis endpoint which uses the InsertList statement type, as shown below: 102.9.2. Using UpdateList StatementType MyBatis allows you to update multiple rows using its for-each batch driver. To use this, you need to use the <foreach> in the mapper XML file. For example as shown below: <update id="batchUpdateAccount" parameterType="java.util.Map"> update ACCOUNT set ACC_EMAIL = #{emailAddress} where ACC_ID in <foreach item="Account" collection="list" open="(" close=")" separator=","> #{Account.id} </foreach> </update> Then you can update multiple rows, by sending a Camel message to the mybatis endpoint which uses the UpdateList statement type, as shown below: from("direct:start") .to("mybatis:batchUpdateAccount?statementType=UpdateList") .to("mock:result"); 102.9.3. Using DeleteList StatementType MyBatis allows you to delete multiple rows using its for-each batch driver. To use this, you need to use the <foreach> in the mapper XML file. For example as shown below: <delete id="batchDeleteAccountById" parameterType="java.util.List"> delete from ACCOUNT where ACC_ID in <foreach item="AccountID" collection="list" open="(" close=")" separator=","> #{AccountID} </foreach> </delete> Then you can delete multiple rows, by sending a Camel message to the mybatis endpoint which uses the DeleteList statement type, as shown below: from("direct:start") .to("mybatis:batchDeleteAccount?statementType=DeleteList") .to("mock:result"); 102.9.4. Notice on InsertList, UpdateList and DeleteList StatementTypes Parameter of any type (List, Map, etc.) can be passed to mybatis and an end user is responsible for handling it as required with the help of mybatis dynamic queries capabilities. 102.9.5. cheduled polling example This component supports scheduled polling and can therefore be used as a Polling Consumer. For example to poll the database every minute: from("mybatis:selectAllAccounts?delay=60000") .to("activemq:queue:allAccounts"); See "ScheduledPollConsumer Options" on Polling Consumer for more options. Alternatively you can use another mechanism for triggering the scheduled polls, such as the Timer or Quartz components. In the sample below we poll the database, every 30 seconds using the Timer component and send the data to the JMS queue: from("timer://pollTheDatabase?delay=30000") .to("mybatis:selectAllAccounts") .to("activemq:queue:allAccounts"); And the MyBatis SQL mapping file used: <!-- Select with no parameters using the result map for Account class. --> <select id="selectAllAccounts" resultMap="AccountResult"> select * from ACCOUNT </select> 102.9.6. Using onConsume This component supports executing statements after data have been consumed and processed by Camel. This allows you to do post updates in the database. Notice all statements must be UPDATE statements. Camel supports executing multiple statements whose names should be separated by commas. The route below illustrates we execute the consumeAccount statement data is processed. This allows us to change the status of the row in the database to processed, so we avoid consuming it twice or more. And the statements in the sqlmap file: 102.9.7. Participating in transactions Setting up a transaction manager under camel-mybatis can be a little bit fiddly, as it involves externalizing the database configuration outside the standard MyBatis SqlMapConfig.xml file. The first part requires the setup of a DataSource . This is typically a pool (either DBCP, or c3p0), which needs to be wrapped in a Spring proxy. This proxy enables non-Spring use of the DataSource to participate in Spring transactions (the MyBatis SqlSessionFactory does just this). <bean id="dataSource" class="org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy"> <constructor-arg> <bean class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="org.postgresql.Driver"/> <property name="jdbcUrl" value="jdbc:postgresql://localhost:5432/myDatabase"/> <property name="user" value="myUser"/> <property name="password" value="myPassword"/> </bean> </constructor-arg> </bean> This has the additional benefit of enabling the database configuration to be externalized using property placeholders. A transaction manager is then configured to manage the outermost DataSource : <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> A mybatis-spring SqlSessionFactoryBean then wraps that same DataSource : <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <!-- standard mybatis config file --> <property name="configLocation" value="/META-INF/SqlMapConfig.xml"/> <!-- externalised mappers --> <property name="mapperLocations" value="classpath*:META-INF/mappers/**/*.xml"/> </bean> The camel-mybatis component is then configured with that factory: <bean id="mybatis" class="org.apache.camel.component.mybatis.MyBatisComponent"> <property name="sqlSessionFactory" ref="sqlSessionFactory"/> </bean> Finally, a transaction policy is defined over the top of the transaction manager, which can then be used as usual: <bean id="PROPAGATION_REQUIRED" class="org.apache.camel.spring.spi.SpringTransactionPolicy"> <property name="transactionManager" ref="txManager"/> <property name="propagationBehaviorName" value="PROPAGATION_REQUIRED"/> </bean> <camelContext id="my-model-context" xmlns="http://camel.apache.org/schema/spring"> <route id="insertModel"> <from uri="direct:insert"/> <transacted ref="PROPAGATION_REQUIRED"/> <to uri="mybatis:myModel.insert?statementType=Insert"/> </route> </camelContext> 102.10. MyBatis Spring Boot Starter integration Spring Boot users can use mybatis-spring-boot-starter artifact provided by the mybatis team <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.3.0</version> </dependency> in particular AutoConfigured beans from mybatis-spring-boot-starter can be used as follow: #application.properties camel.component.mybatis.sql-session-factory=#sqlSessionFactory 102.11. Spring Boot Auto-Configuration The component supports 11 options, which are listed below. Name Description Default Type camel.component.mybatis-bean.autowired-enabled Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. true Boolean camel.component.mybatis-bean.configuration-uri Location of MyBatis xml configuration file. The default value is: SqlMapConfig.xml loaded from the classpath. SqlMapConfig.xml String camel.component.mybatis-bean.enabled Whether to enable auto configuration of the mybatis-bean component. This is enabled by default. Boolean camel.component.mybatis-bean.lazy-start-producer Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false Boolean camel.component.mybatis-bean.sql-session-factory To use the SqlSessionFactory. The option is a org.apache.ibatis.session.SqlSessionFactory type. SqlSessionFactory camel.component.mybatis.autowired-enabled Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. true Boolean camel.component.mybatis.bridge-error-handler Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false Boolean camel.component.mybatis.configuration-uri Location of MyBatis xml configuration file. The default value is: SqlMapConfig.xml loaded from the classpath. SqlMapConfig.xml String camel.component.mybatis.enabled Whether to enable auto configuration of the mybatis component. This is enabled by default. Boolean camel.component.mybatis.lazy-start-producer Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false Boolean camel.component.mybatis.sql-session-factory To use the SqlSessionFactory. The option is a org.apache.ibatis.session.SqlSessionFactory type. SqlSessionFactory

Commands:
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-mybatis-starter</artifactId> </dependency>
mybatis:statementName[?options]
mybatis:statement
from("activemq:queue:newAccount") .to("mybatis:insertAccount?statementType=Insert");
<!-- Insert example, using the Account parameter class --> <insert id="insertAccount" parameterType="Account"> insert into ACCOUNT ( ACC_ID, ACC_FIRST_NAME, ACC_LAST_NAME, ACC_EMAIL ) values ( #{id}, #{firstName}, #{lastName}, #{emailAddress} ) </insert>
<update id="batchUpdateAccount" parameterType="java.util.Map"> update ACCOUNT set ACC_EMAIL = #{emailAddress} where ACC_ID in <foreach item="Account" collection="list" open="(" close=")" separator=","> #{Account.id} </foreach> </update>
from("direct:start") .to("mybatis:batchUpdateAccount?statementType=UpdateList") .to("mock:result");
<delete id="batchDeleteAccountById" parameterType="java.util.List"> delete from ACCOUNT where ACC_ID in <foreach item="AccountID" collection="list" open="(" close=")" separator=","> #{AccountID} </foreach> </delete>
from("direct:start") .to("mybatis:batchDeleteAccount?statementType=DeleteList") .to("mock:result");
from("mybatis:selectAllAccounts?delay=60000") .to("activemq:queue:allAccounts");
from("timer://pollTheDatabase?delay=30000") .to("mybatis:selectAllAccounts") .to("activemq:queue:allAccounts");
<!-- Select with no parameters using the result map for Account class. --> <select id="selectAllAccounts" resultMap="AccountResult"> select * from ACCOUNT </select>
<bean id="dataSource" class="org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy"> <constructor-arg> <bean class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="org.postgresql.Driver"/> <property name="jdbcUrl" value="jdbc:postgresql://localhost:5432/myDatabase"/> <property name="user" value="myUser"/> <property name="password" value="myPassword"/> </bean> </constructor-arg> </bean>
<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <!-- standard mybatis config file --> <property name="configLocation" value="/META-INF/SqlMapConfig.xml"/> <!-- externalised mappers --> <property name="mapperLocations" value="classpath*:META-INF/mappers/**/*.xml"/> </bean>
<bean id="mybatis" class="org.apache.camel.component.mybatis.MyBatisComponent"> <property name="sqlSessionFactory" ref="sqlSessionFactory"/> </bean>
<bean id="PROPAGATION_REQUIRED" class="org.apache.camel.spring.spi.SpringTransactionPolicy"> <property name="transactionManager" ref="txManager"/> <property name="propagationBehaviorName" value="PROPAGATION_REQUIRED"/> </bean> <camelContext id="my-model-context" xmlns="http://camel.apache.org/schema/spring"> <route id="insertModel"> <from uri="direct:insert"/> <transacted ref="PROPAGATION_REQUIRED"/> <to uri="mybatis:myModel.insert?statementType=Insert"/> </route> </camelContext>
<dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.3.0</version> </dependency>
#application.properties camel.component.mybatis.sql-session-factory=#sqlSessionFactory