Spring Tutorial

Core

IoC
DI
Beans
- Step1: Creating beans
  - @Bean
  - @Component
- Step2: Wiring (@Autowiring)
Context
SpEL
IoC Container

Stereotype Annotations

@Component
- @Controller
- @Service
- @Repository

Bean Scope

Singleton
- use case:
  - immutable beans
  - service layers
  - repository layers
- points:
  - mutable singleton beans + multi thread environment => race condition
  - mutable singleton beans + multi thread environment + synchronization => NOT race condition
  - NOT best practice = bad practice => mutable singleton beans
Prototype
Request
Session
Application

Aspect Oriented Programming (AOP)

WWW
- What -> Aspect
- When -> Advice
- Witch -> Pointcut
- Join Point
- Target Object

Proxy Object of beans
- Weaving
- intercept
- delegate

Advice:
1. @Before
2. @AfterReturning
3. @AfterThrowing
4. @After
5. @Around

Web App

Web Server
- Servlet Container (Http web server -> Http servlet object)
  - in: ServletRequest
  - out: ServletResponse
  - Apache Tomcat

Dispatcher Servlet

before:
- /home => HomeServlet
- /about => AboutServlet
- /... => ...Servlet
after:
- /* => DispatcherServlet

Web application

Approach 1: Spring MVC + Spring Core + Spring Boot + ...
Approach 2: Spring Core + Spring Boot + ...

Spring Boot

SpringBoot Starters
- spring-boot-starter-web
Autoconfiguration
- convention-over-configuration
Actuator and DevTools
- monitor app health, metrics, etc.
- LiveReload Server

Java Template Engine

Thymeleaf
Apache FreeMarker
jte
Jakarta Server Page (JSP)
Jakarta Server Face (JSF)
- PrimeFace
...

Fetching Data

@PathVariable
- www.jimsa.be/app/course <- Path variable
@RequestParam
- www.jimsa.be/app?course=math&active=true <- Query Param
- Form data

Validation

spring-boot-starter-validation:
1. jakarta.validation.constraints.*
  - @Digits
  - @Email
  - @Max
  - @Min
  - @Not...
  - @Pattern
  - @Size
2. org.hibernate.validator.constraints.*
  - @CreditCardNumber
  - @Length
  - Currency
  - @Range
  - @URL
  - @UniqueElements
  - @EAN
  - @ISBN

Spring Web Scope

Singleton
Prototype

Request
- @RequestScope
Session
- @SessionScope
Application
- ApplicationScope

Security

Thymeleaf Extras Springsecurity6
CSRF

Encoding
- unicode
- base64
- ascii
- file formats
Encryption
- key
- encryption
Hashing
- hash value
- hashing function

Password Encoder (using hash algorithms)
- NoOpPasswordEncoder (No hashing stories in plain text)
- StandardPasswordEncoder
- Pbkdf2PasswordEncoder
- BCryptPasswordEncoder (most commonly use)
- SCryptPasswordEncoder

Database

H2
- in-memory
- schema.sql
- data.sql
- /h2-console
- sa & ''

JDBC
- loading driver
- management connections
- statements
- resultSets
- ...

Spring JDBC
- spring-boot-starter-jdbc
- JdbcTemplate

String lastName = this.jdbcTemplate.queryForObject(
        "select last_name from users where id = ?",
        String.class,
        123L
);

NamedParameterJdbcTemplate

public int getCount(String firstName) {
    String sql = "select count(*) from users where first_name = :first_name";
    SqlParameterSource namedParameters = new SqlParameterSource("first_name", firstName);
    return this.namedParameterJdbcTemplate.queryForObject(
            sql,
            namedParameters,
            Integer.class
    );
}

Using RowMapper
- BeanPropertyRowMapper
application.properties
- spring.jdbc.template.*
- spring.jdbc.template.max-rows=500

Spring Data Projects Link
- Projects:
  - Spring Data JDBC
  - Spring Data JPA
  - Spring Data LDAP
  - Spring Data MongoDB
  - Spring Data Redis
  - Spring Data R2DBC
  - Spring Data REST
  - Spring Data for Apache Cassandra
  - Spring Data for Apache Geode
  - Spring Data Couchbase (community module)
  - Spring Data Elasticsearch (community module)
  - Spring Data Envers
  - Spring Data Neo4j (community module)
  - ...
- Main modules
  - Spring Data Commons
    - Repository (marker interface)
      - CrudRepository
        
        ListCrudRepository
      - PagingAndSortingRepository
        
        ListPagingAndSortingRepository
  - Spring Data JPA
    - JpaRepository
- Community modules

Project

create a standalone Spring App which use two databases like MySql and PostgreSQL!

dependency

application.yml (application.properties)

spring.datasource.mysql/postgres.url/username/password/driver-class-name

jpa.hibernate.ddl-auto

jpa.mysql/postgres.properties.hibernate.dialect

DataSource

EntityManager

TransactionManager

LocalContainerEntityManagerFactoryBean

EntityManagerFactoryBuilder

PlatformTransactionManager

JpaTransactionManager

@Primary

@Qualifier

@PersistenceContext(unitName = "mysqlPU")

private EntityManager mysqlEntityManager;

@PersistenceContext(unitName = "postgresPU")

private EntityManager postgresEntityManager;

JConnector
JDBC
JPA
Spring Data
Spring Data JPA
Hibernate

Query Methods in Spring Data JPA
- introducer + By + criteria
Auditing Support by Spring Data JPA
- @CreatedDate
- @CreatedBy
- @LastModifiedDate
- @LastModifiedBy

Custom Validation

@interface...
impl ...
using ...

import jakarta.persistence.Transient;

@Transient
private String noDbOp; // Won't participate in DB operations like creating a table's column

Database Relations

IMPORTANT : Link

Sorting

static
- findByOrderByNameDesc()
dynamic
- Sort.by("name").descending().and(Sort.by("age"))

Paging

import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;

Pageable pageable = PageRequest.of(
        0,
        10,
        Sort.by("name").descending()
);
Page<Person> personPage = repo.findByName(name, pageable);

Custom Query with JPA

@Query
- JPQL
- Native SQL query (nativeQuery=true)
@NamedQuery
@NamedNativeQuery
- Spring Data JPA doesn’t support dynamic sorting for native queries
- Example:
  - Link 1
  - Link 2

Update, Delete, Insert
- @Transactional
- @Modifying

Rest APIs

@RestController = @Controller + @ResponseBody
@RestControllerAdvice
ReponseEntity<T>
RequestEntity<T> -> getBody()
@RequestHeader
@RequestBody

Cross-origin resource sharing (CORS)

protocol
domain
port
@CrossOrigin("*")

Jackson JSON

link

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;

import java.time.LocalDateTime;

@JsonProperty("first_name")
private String firstName;

@JsonIgnore
private LocalDateTime createdAt;

Requests:

curl --location 'http://localhost:8090/springapp/api/person'

curl --location --request GET 'http://localhost:8090/springapp/api/person/byRequestBodyAnnotation' \
--header 'Content-Type: application/json' \
--data '{
    "first_name": "jimsa2",
    "last_name": "salehi2"
}'

curl --location 'http://localhost:8090/springapp/api/person' \
--header 'invocationFrom: mobile' \
--header 'Content-Type: application/json' \
--data '{
    "first_name": "jimsa3",
    "last_name": "salehi3"
}'

curl --location --request DELETE 'http://localhost:8090/springapp/api/person' \
--header 'Content-Type: application/json' \
--data '{
    "first_name": "jimsa4",
    "last_name": "salehi4"
}'

curl --location --request PATCH 'http://localhost:8090/springapp/api/person' \
--header 'Content-Type: application/json' \
--data '{
    "first_name": "jimsa6"
}'

Rest APIs consuming

IMPORTANT : Link

Spring Data Rest & HAL Explorer

link1
link2
link3

Logging

AOP -> MyLogAspect

Libs:

Java util logging
Log4J2
SLF4J
Logback
- The default logging framework
- The default logging destination is the console
  - System.out
  - System.err
- Link

Levels:

fatal
error
warn
info
debug
trace

Configuration

@Value
environment.getProperty("...")
-> default into application.properties

Profile

application_prod.properties
application_dev.properties

spring.profiles.active

@Profile("!dev")

Spring Actuator and Spring Boot Admin

http://localhost:8090/springapp/actuator/
management.endpoints.web.exposure.include=*

Spring Boot Admin
- client
  - link
- server
  - link
- hibernate-micrometer
  - link

Heap Dumps

JDK Tools
- jmap
- jcmd
- JVisualVM
Automatically
- java -XX:+HeapDumpOnOutOfMemoryError
- java -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=<file-or-dir-path>
JMX
- JConsole
- Programmatic Way

public static void dumpHeap(String filePath, boolean live) throws IOException {
    MBeanServer server = ManagementFactory.getPlatformMBeanServer();
    HotSpotDiagnosticMXBean mxBean = ManagementFactory.newPlatformMXBeanProxy(
      server, "com.sun.management:type=HotSpotDiagnostic", HotSpotDiagnosticMXBean.class);
    mxBean.dumpHeap(filePath, live);
}

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README.md

README.md

Spring Tutorial

Core

Stereotype Annotations

Bean Scope

Aspect Oriented Programming (AOP)

Web App

Dispatcher Servlet

Web application

Spring Boot

Java Template Engine

Fetching Data

Validation

Spring Web Scope

Security

Database

Project

Custom Validation

Database Relations

Sorting

Paging

Custom Query with JPA

Rest APIs

Cross-origin resource sharing (CORS)

Jackson JSON

Rest APIs consuming

Spring Data Rest & HAL Explorer

Logging

Configuration

Profile

Spring Actuator and Spring Boot Admin

Files

README.md

Latest commit

History

README.md

File metadata and controls

Spring Tutorial

Core

Stereotype Annotations

Bean Scope

Aspect Oriented Programming (AOP)

Web App

Dispatcher Servlet

Web application

Spring Boot

Java Template Engine

Fetching Data

Validation

Spring Web Scope

Security

Database

Project

Custom Validation

Database Relations

Sorting

Paging

Custom Query with JPA

Rest APIs

Cross-origin resource sharing (CORS)

Jackson JSON

Rest APIs consuming

Spring Data Rest & HAL Explorer

Logging

Configuration

Profile

Spring Actuator and Spring Boot Admin