Spring IO Platform is all about “list of dependencies and their versions that work well together”. It is implemented as a Maven POM file via Maven Bill-of-Materials dependency that you can import into your projects to set the versions for dependencies. You can go to “ … Read more ›...
conf/db.properties
# jdbc.X
jdbc.driverClassName=org.hsqldb.jdbcDriver
jdbc.url=jdbc:hsqldb:hsql://localhost/mytestdb
jdbc.user=SA
jdbc.pass=
# hibernate.X
hibernate.dialect=org.hibernate.dialect.HSQLDialect
hibernate.show_sql=false
hibernate.hbm2ddl.auto=
#1. Register a Properties File in Application Context XML
The “<property-placeholder>” tag.
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<context:property-placeholder location="classpath:conf/db.properties" /> |
OR
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<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>classpath:conf/db.properties</value> </list> </property> <property name="ignoreUnresolvablePlaceholders" value="true"/> </bean> |
#2.
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This extedns configuring JDBC and JPA to configure the TransactionManager.
Example #1 Wiring JDBC Transaction Manager
Note: @EnableTransactionManagement annotation
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@Configuration @ImportResource("application.yml") @EnableTransactionManagement public class AppConfig @Bean public DriverManagerDataSource datasource() { DriverManagerDataSource ds = new DriverManagerDataSource(); ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name")); ds.setUrl(environment.getRequiredProperty("spring.datasource.url")); ds.setUsername(environment.getRequiredProperty("spring.datasource.username")); ds.setPassword(environment.getRequiredProperty("spring.datasource.password")); return ds; } @Bean public JdbcTemplate jdbcTemplate() { return new JdbcTemplate(datasource()); } @Bean public DataSourceTransactionManager transactionManager() { final DataSourceTransactionManager transactionManager = new DataSourceTransactionManager(datasource()); return transactionManager; } } |
If you want to create a mock transaction manager, then you can do
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package sample; import org.springframework.stereotype.Service; import org.springframework.transaction.PlatformTransactionManager; import org.springframework.transaction.TransactionDefinition; import org.springframework.transaction.TransactionException; import org.springframework.transaction.TransactionStatus; public class MockedTransactionManager implements PlatformTransactionManager { @Override public TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException { return null; } @Override public void commit(TransactionStatus status) throws TransactionException { } @Override public void rollback(TransactionStatus status) throws TransactionException { } } |
Also,
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Example #1 Wiring JDBC Datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DriverManagerDataSource datasource() { DriverManagerDataSource ds = new DriverManagerDataSource(); ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name")); ds.setUrl(environment.getRequiredProperty("spring.datasource.url")); ds.setUsername(environment.getRequiredProperty("spring.datasource.username")); ds.setPassword(environment.getRequiredProperty("spring.datasource.password")); return ds; } } |
application.yml where the datasource properties are read.
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############ # Datasource properties ############ spring: datasource: driver-class-name: com.sybase.jdbc4.jdbc.SybDataSource url: jdbc:sybase:Tds:mydbhost:5700/my_db username: user password: pwd |
Example #2 Wiring JDBC Datasource with JNDI
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final JndiDataSourceLookup jndiLookup = new JndiDataSourceLookup(); final String dataSourceJndi = environment.getRequiredProperty("spring.datasource.jndi"); return jndiLookup.getDataSource(dataSourceJndi); } } |
Example #3 Wiring JDBC Embedded Datasource for integration testing
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder(); builder.setType(EmbeddedDatabaseType.HSQL); builder.addScript("classpath:hsqldb-oracle.sql"); builder.addDefaultScripts(); // defaults are schema.sql and data.sql return builder.build(); } } |
Example #4 Wiring up the JdbcTemplate by passing in the datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public JdbcTemplate jdbcTemplate() { return new JdbcTemplate(datasource()); } @Bean public DataSource dataSource() { //...... } } |
Example #5 Wiring up a DAO...
Step 1: Define the messaging system connectivity, destination (e.g. topic or queue) and message selector properties via a YAML or .properties file. Here is an example of application.yml file.
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############################# # MQ Settings # ############################# spring: mq: hostname: my-mq-host channel: mychannel port: 2500 queue.manager: GHTFDS environment: EN7 # MQ SSL settings -- uncomment the below section to enable SSL for MQ # ssl: # enabled: # cipher.suite: # keyStore: # keyStorePassword: # MQ misc settings, if not set, will set with sensible defaults # transport.type: 1 # client.id: YOUR_CLIENT_NAME # delivery.mode: 2 ############################################### # topic selector # ############################################### myapp: app: title: my app systemname: send-prices PriceSubscriptionName: price_event selector: PriceEventTopic: TOPIC/PRICE PriceEventMessageType: event PriceEventOriginator: PRICE PriceEventCategory: business/price |
Step 2: MQTopicConnectionFactory The Java based Spring configuration defining the connection factory. … Read more ›...
Q. If Java did not have a Stack implementation, how would you go about implementing your own? A. Determine the backing data structure (e.g. array, linked list, etc). Determine the methods that need to be implemented like pop( ), push( ), … Read more ›...
Q1. Can you write an algorithm to swap two values? A1.
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package algorithms; public class Swap { public static void main(String[ ] args) { int x = 5; int y = 6; //store 'x' in a temp variable int temp = x; x = y; y = temp; System.out.println("x=" + x + ",y=" + y); } } |
Swapping without a temp variable
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package algorithms; public class Swap { public static void main(String[ ] args) { int x = 5; int y = 6; //without using a temp variable x = x + y; // 11 y = x - y; // 5 x = x - y; //6 System.out.println("x=" + x + ",y=" + y); } } |
Note: also try with * and \ Using bitwise “xor”
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package algorithms; public class Swap { public static void main(String[ ] args) { int x = 5; int y = 6; //without using a temp variable //^ is xor 0 ^ 0 = 0, 0 ^ 1 = 1, 1 ^ 0 = 1, 0 ^ 0 = 0 x = x ^ y; // 3 y = x ^ y; // 5 x = x ^ y; //6 System.out.println("x=" + x + ",y=" + y); } } |
Q2. … Read more ›...
Q1. Can you write an algorithm in Java to swap two variables? A1.
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public class Swap { public static void main(String[ ] args) { int x = 5; int y = 6; //store 'x' in a temp variable int temp = x; x = y; y = temp; System.out.println("x=" + x + ",y=" + y); } } |
Q2. Can you write an algorithm to bubble sort the following array { 30, 12, 18, 0, -5, 72, 424 }?? … Read more ›...
Cause #1: The JVM spends more time performing garbage collection due to improper Garbage Collection (GC) configuration. E.g. Young generation being too small. Heap size is too small (use -Xmx). The application footprint is larger than the allocated heap size. … Read more ›...
Q. How will you partition the following numbers 7 3 6 8 2 9 5 4 around the pivotal number of 5 so that the lower values are in front of it and higher values are behind it? The pointers are shown with: “^” … Read more ›...
This post extends the previous one on “Unit Test Hibernate – DAO Layer with Spring & HSQLDB“. The changes are
1. Add “persistence-jpa.xml” to src/main/resources.
2. Modify the “entityManagerFactory()” method in the “SimpleConfig.java”.
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Step 1: The pom.xml file with test jars, Spring jars, and hibernate jars
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.mytutorial</groupId> <artifactId>simpleSpringRestWeb</artifactId> <version>1.0-SNAPSHOT</version> <packaging>war</packaging> <name>simpleSpringRestWeb</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <slf4j.version>1.7.10</slf4j.version> <commons-logging.version>1.1.1</commons-logging.version> <spring.version>4.0.9.RELEASE</spring.version> </properties> <dependencies> <!-- Unit Testing--> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.11</version> <scope>test</scope> </dependency> <dependency> <groupId>org.mockito</groupId> <artifactId>mockito-all</artifactId> <version>1.9.0</version> <scope>test</scope> </dependency> <dependency> <groupId>org.hamcrest</groupId> <artifactId>hamcrest-all</artifactId> <version>1.3</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>com.jayway.jsonpath</groupId> <artifactId>json-path</artifactId> <version>0.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>com.jayway.jsonpath</groupId> <artifactId>json-path-assert</artifactId> <version>0.8.1</version> <scope>test</scope> </dependency> <!-- Hibernate --> <dependency> <groupId>org.hibernate.common</groupId> <artifactId>hibernate-commons-annotations</artifactId> <version>4.0.1.Final</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.hibernate.javax.persistence</groupId> <artifactId>hibernate-jpa-2.0-api</artifactId> <version>1.0.1.Final</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>4.2.0.SP1</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>4.2.0.SP1</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-ehcache</artifactId> <version>4.2.0.SP1</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.jboss.jbossts</groupId> <artifactId>jbossjta</artifactId> <version>4.16.4.Final</version> </dependency> <!-- HSQLDB --> <dependency> <groupId>org.hsqldb</groupId> <artifactId>hsqldb</artifactId> <version>2.3.2</version> </dependency> <!-- Spring --> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-jpa</artifactId> <version>1.5.1.RELEASE</version> <exclusions> <exclusion> <groupId> org.springframework</groupId> <artifactId>spring-jdbc</artifactId> </exclusion> <exclusion> <groupId> org.springframework</groupId> <artifactId>spring-core</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-beans</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-expression</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring.version}</version> </dependency> <!-- Other --> </dependencies> </project> |
Step 2: The HSQL DB schema and data scripts in the src/test/resources folder.
sql/schema.sql
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CREATE TABLE tbl_person ( person_id int NOT NULL , person_gender varchar(6) NOT NULL , person_name varchar(100) NOT NULL , person_age int NOT NULL ); CREATE UNIQUE INDEX idx_tbl_person ON tbl_person(person_id) |
sql/data.sql
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INSERT INTO tbl_person (person_id, person_gender, person_name, person_age) VALUES ( 1, 'MALE', 'John', 23); INSERT INTO tbl_person (person_id, person_gender, person_name, person_age) VALUES ( 2, 'FEMALE', 'Mary', 23); |
Step 3: The Spring configuration for the unit tests in the src/test/java folder.
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Most interviewers like Java candidates those who are passionate and experienced about writing unit tests. Any non trivial Java application will be making calls to database tables. So, here are a few questions and answers testing your ability to write unit tests to test data access layer.
Q1.
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