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JPA For Beginner. Your Step-By-Step Guide To Learn JPA Framework 2024 (Amit K.) (Z-Library)
JPA For Beginner. Your Step-By-Step Guide To Learn JPA Framework 2024 (Amit K.) (Z-Library)
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' » i Aifriitj K f, Th PROGRAMMING CRASH COURSE DAYS With Hands-On Exercises and Code Snippets
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JPA JAVA PERSISTENCE FOR BEGINNERS In This Book You Will Learn Explanation with Diagramme and Working Exercises with Successfull Execution of Exercises with Output Readymade Solution With Step By Step Explanation
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AMITK Contents Beginners Guide to Learn JPA Programming Step by Step Introduction Chapter 1: JPA One to One Mapping 1 Example 1: JPA OneToOne Mapping 2 Example 2 : JPA OneToOne Lazy Load Mapping 3 Example 3 : JPA OneToOne Join Column Mapping 4 Example 4 : JPA OneToOne Primary Key Join Column Mapping 5 Example 5 : JPA OneToOne Map Cascade Mapping 6 Example 6 : JPA OneToOne Unidirectional Mapping
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7 Example 7 : JPA OneToOne Bidirectional Mapping Chapter 2 : JPA One to Many Mapping 1 Example 8 : JPA OneToMany Mapping 2 Example 9 : JPA OneToMany Join Table Mapping 3 Example 10: JPA OneToMany Unidirectional Mapping 4 Example 11: JPA OneToMany OrderBy Mapping 5 Example 12: JPA Persist OrderedList Mapping 6 Example 13: JPA OneToMany Map Key Mapping 7 Example 14: JPA OneToMany Untyped Mapping Chapter 3 : JPA Many to One Mapping 1 Example 15: JPA ManyToOne Mapping 2 Example 16: JPA ManyToOne Join Columns Mapping 3 Example 17: JPA ManyToOne Join Column Mapping Chapter 4: JPA Many to Many Mapping 1 Example 18: JPA ManyToMany Mapping 2 Example 19: JPA ManyToMany Join Table Mapping
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3 Example 20: JPA ManyToMany Bidirectional Mapping 4 Example 21: JPA ManyToMany Embeddable Mapping Introduction Learning JPA Programming step by step. JPA (Java Persistence API) is a powerful framework that can be used to quickly build robust data- driven application. Most of the data that our applications manipulate have to be stored in data stores, retrieved, processed and analyzed. If this data store is a relational database and you use an object-oriented programming language such as Java, then you should have a look at JPA.
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JPA is an Object-Relational Mapping tool that maps Java objects to relational databases and allows query operations. In this book, you will learn Java Persistence API, its annotations for mapping entities. JPA Integration with spring frameworks. Different Scenario (To Apply > Different Types of Mapping) Suppose There is to Two Object , Student and dress Student and Addr Want to Communicate to each other. Student want to Access -> Details of Address object. Student want to Access -> Details of AND Also want to Access-> Details of Student object Then How to do this , How to Achieve this Scenario Then there is a Mechanism to Achieve this Scenario , through Primary Key and <ey. between Primary Key and then onlyIf any how we will Establish Relationship Student Top i Uni Directional Mapping ▼ Address Bottom Student Address 4 i Bi ♦ Top Directional Mapping Bo* Bottom
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Chapter 1: JPA One to One Mapping 1 JPA OneToOne Mapping 2 JPA OneToOne Lazy Load Mapping 3 JPA OneToOne Join Column Mapping 4 JPA OneToOne Primary Key Join Column Mapping 5 JPA OneToOne Map Cascade Mapping 6 JPA OneToOne Unidirectional Mapping
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7 JPA OneToOne Bidirectional Mapping 1 JPA OneToOne Mapping Person t Department Here you will learn how to do one to one map in JPA mapping.
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This example assumes that one Person can only be part of one department and one department can only have one person. In Person entity we mark the Department reference property with ©OneToOne annotation. ©Entity public class Person { • • • ©OneToOne private Department department; Here is the simple code to setup the two entities and save them to database. Person pl = new Person("Tom"); p 1 .setName("Tom"); Department d = new Department); d.setName("Design"); p 1 .setDepartment(d); em.persist(pl);
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em.persist(d); Example 1: In This example assumes that one Person can only be part of one department and one department can only have one person. Person.java package com.abd.jpa; import javax.persistence.Entity; import j avax.persistence.GeneratedValue; import j avax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.One ToOne; ©Entity public class Person { ©Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id;
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private String name; ©OneToOne private Department department; public Person() {} public Person(String name) { this.name = name; public Department getDepartment() { return department; public void setDepartment(Department department) { this.department = department; public Long getld() { return id; public void set!d(Long id) { this.id = id;
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public String getNameQ { return name; public void setName(String name) { this.name = name; ©Override public String toStringO { return "Person [id=" + id + ", name=" + name + "]"; Department.java package com.abd.jpa; import javax.persistence.Entity; import j avax.persistence.GeneratedValue; import j avax.persistence.GenerationType; import javax.persistence.Id;
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©Entity public class Department { ©Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private String name; public long getld() { return id; public void setld(long id) { this.id = id; public String getNameQ { return name; public void setName(String name) { this.name = name;
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PersonDaoImpl.java package com.abd.jpa; import javax.persistence.EntityManager; import javax.persistence.Persistencecontext; import org.springframework.transaction.annotation.Transactional; ©Transactional public class PersonDaoImpl { public void test(){ Person pl = new Person("Tom"); p 1 .setName("Tom"); Department d = new Department); d.setName("Design"); p 1 .setDepartment(d); em.persist(pl);
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em.persist(d); ©Persistencecontext private EntityManager em; Helper.java package com.abd.jpa; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class Helper { public static void checkData() { try{ Class.forName("com.mysql.jdbc.Driver"); Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/dbl", "root", "root"); Statement st = conn.createStatementQ;
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ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String!] {"TABLE"}); while (mrs.next()) { String tableName = mrs.getString(3); System.out.println("\n\n\n\nTable Name:"+ tableName); ResultSet rs = st.executeQueryf'select * from" + tableName); ResultSetMetaData metadata = rs.getMetaDataQ; while (rs.nextQ) { System.out.println(" Row:"); for (int i = 0; i < metadata.getColumnCount(); i++) { System.out.println(" Column Name:"+ metadata.getColumnLabel(i + 1)+ ", "); System.out.println(" Column Type:"+ metadata.getColumnTypeName(i + 1)+ ": " Object value = rs.getObject(i + 1); System.out.println(" Column Value:"+value+"\n"); }catch(Exception e){ e.printStackTrace();
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persistence.xml < ?xml version=" 1.0" encoding="UTF-8"? > persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/ XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/per- sistence/persistence_l_O.xsd"> < persistence-unit name-'jpaData" /> </persistence > applicationContext.xml < ?xml version=" 1.0" encoding="UTF-8"? >
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<beans xmlns="http://www.springframework.org/schema/beans" xmlns:aop="http://www.springframework.org/schema/aop"xmlns:context="http:// www.springframework.org/schema/context" xmlns:security="http://www.springframework.org/schema/security" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http:// www.w3 .org/ 2001 /XMLSchema-instance" xsi: schemaLocation=" http://www.springframework.Org/schema/aophttp://www.springframework.org/schema/aop/ spring-aop- 3.2 .xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/ beans/spring-beans- 3.2 .xsd http://www.springframew0rk.0rg/schema/c0ntexthttp://www.springframew0rk.0rg/schema/ context/spring-context-3.2 .xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/ spring-tx- 3.2 .xsd" > < tx: annotation-driven /> <context:annotation-config /> <bean id="personDao" class="com.abd.jpa.PersonDaoImpl" /> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
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<property name="driverClassName" > <value>com.mysql.jdbc.Driver</value> < /property > < property name="url" > < value >jdbc:mysql://localhost/db 1 </value> < /property > < property name="username" > < value > root < / value > < /property > < property name="password" > < value > root < / value > < /property > </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref = "dataSource" /> <property name="persistenceUnitName" value="jpaData" /> < property name="jpaVendorAdapter" > <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendor Adapter" I > < /property > < property name="jpaProperties" >
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< props> <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop> < prop key="hibernate.show_sql">true</prop> <prop key="hibernate.hbm2ddl.auto">update</prop> < /props > < /property > </bean> <bean id="transactionManager" class="org.springframework.orm.jpaJpaTransactionManager"> < property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> </beans> Client.java package com.abd.jpa; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Client { public static void main(String[] args) {
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# JPA For Beginner: Your Step-By-Step Guide To Learn JPA Framework 2024 — Reading Guide
## 【One-Line Pitch】
A hands-on, example-driven crash course for Java developers who want to master JPA (Java Persistence API) entity mappings — from one-to-one to many-to-many — through 21 worked exercises with code snippets and step-by-step explanations. If you learn best by typing code and seeing output, this is your entry point into object-relational mapping.
## 【Book Arc】
- **Opening (~0%)**: Introduces JPA as an Object-Relational Mapping (ORM) tool that bridges Java objects and relational databases, explaining why any Java developer working with relational data stores should learn it. Sets up the core problem: how two objects (e.g., Student and Address) communicate and access each other's details through primary keys and relationships.
- **Early (~0%–25%)**: Chapter 1 covers **One-to-One mappings** through 7 examples — basic mapping, lazy loading, join column configuration, primary key join columns, cascade operations, and the crucial distinction between unidirectional and bidirectional relationships.
- **Middle (~25%–60%)**: Chapter 2 explores **One-to-Many mappings** with 7 examples, including join table strategies, unidirectional vs. bidirectional approaches, ordering with `@OrderBy`, ordered lists, map keys, and untyped collections.
- **Late (~60%–85%)**: Chapter 3 handles **Many-to-One mappings** across 3 examples, showing the inverse perspective of one-to-many relationships and how join columns are configured from the "many" side.
- **Ending (~85%–100%)**: Chapter 4 completes the picture with **Many-to-Many mappings** across 4 examples — basic mapping, join table configuration, bidirectional relationships, and embeddable usage. The book closes by revisiting the Student–Address scenario to show how unidirectional and bidirectional mappings solve real communication needs between objects.
## 【Key Takeaways】
- **JPA is an ORM bridge, not a database tool** (Opening): It maps Java objects to relational database tables and enables query operations, letting developers work with objects instead of SQL. This is the foundational mental model for everything that follows.
- **Relationship direction matters more than cardinality** (Early): The book repeatedly contrasts unidirectional vs. bidirectional mappings — choosing the right direction determines which side owns the foreign key and how queries navigate between entities.
- **Lazy loading is a performance lever** (Early): One-to-one mappings can be configured for lazy loading to defer fetching related entities until actually accessed, avoiding unnecessary database hits.
- **Join columns are the physical wiring** (Early–Middle): Whether using `@JoinColumn` or `@PrimaryKeyJoinColumn`, understanding how foreign keys are declared is essential — the book shows multiple configurations for the same relationship type.
- **Cascade operations propagate lifecycle changes** (Early): Cascade mapping lets operations like persist or remove flow from parent to child entities automatically, reducing boilerplate but requiring care about unintended deletions.
- **Collection ordering requires explicit configuration** (Middle): For one-to-many relationships, `@OrderBy` and ordered list mappings give developers control over how child collections are retrieved and presented.
- **Many-to-many relationships need join tables** (Late): The book demonstrates how join table mappings work, including bidirectional variants and embeddable usage for storing extra information about the relationship itself.
- **Real scenarios drive the examples** (Ending): The recurring Student–Address example shows how to decide between unidirectional and bidirectional mappings based on whether both objects need to access each other's details.
## 【Reading Tips】
- **Treat this as a lab manual, not a theory book**: Each of the 21 examples is meant to be executed. Set up a Java project with JPA and a database, then work through examples sequentially — the output verification is part of the learning.
- **Skim the first chapter's basics if you already know ORM concepts**: The introduction is brief; the real value starts with Example 1. Focus your attention on the mapping annotations and configuration variations.
- **Compare examples within each chapter**: Many examples are variations on the same relationship (e.g., unidirectional vs. bidirectional, join column vs. join table). Read them side-by-side to understand when each configuration is appropriate.
- **Watch for the directionality distinction**: This is the hardest conceptual hurdle. When reading each example, ask: "Which side owns the relationship? Which side has the foreign key?" This question clarifies most confusion.
- **Don't skip the Many-to-Many chapter**: It's the shortest but covers the most complex mapping type — embeddable mappings in many-to-many relationships are particularly useful for real-world applications.
## 【Coverage Limits】
The excerpts cover the book's structure, introduction, and the Student–Address scenario but do not include detailed content from the individual examples, Spring framework integration details, or code snippets. This guide reflects the book's organization and pedagogical approach rather than its specific technical implementations.
##
Passage locations
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书名: JPA For Beginner. Your Step-By-Step Guide To Learn JPA Framework 2024 (Amit K.) (Z-Library) 作者: Amit K. ' » i Aifriitj K f, Th PROGRAMMING CRASH COURSE D...
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be stored in data stores, retrieved, processed and analyzed. If this data store is a relational database and you use an object-oriented programming language ...
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