Java Tutorial/JPA/Introduction

Field Injection ID

File: Student.java

   <source lang="java">

import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Student {

 @Id
 private long id = 0;
 private String name;
 public long getId() {
   return id;
 }
 public void setId(long id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }

}</source>

JPA Development Environment Setup

File: Helper.java

   <source lang="java">

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() throws Exception {
   Class.forName("org.hsqldb.jdbcDriver");
   Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
   Statement st = conn.createStatement();
   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.executeQuery("select * from " + tableName);
     ResultSetMetaData metadata = rs.getMetaData();
     while (rs.next()) {
       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");
       }
     }
   }
 }

}</source>

Mark Class As Entity

File: Student.java

   <source lang="java">

import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Student {

 @Id
 private long id = 0;
 private String name;
 public long getId() {
   return id;
 }
 public void setId(long id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }

}</source>

Mark Property Accessor

File: Student.java

   <source lang="java">

import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Student {

 private int id = 0;
 private String name;
 
 @Id
 public int getId() {
   return id;
 }
 public void setId(int id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }
 public String toString() {
   return "\n\nID:" + id + "\nName:" + name + "\n\n";
 }

}</source>

Persistance Configuration

File: Student.java

   <source lang="java">

import java.util.Date; import javax.persistence.Basic; import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Student {

 @Id
 private long id = System.currentTimeMillis();
 @Basic
 private String name;
 @Basic
 private Date dateOfBirth = new Date();
 public Date getDateOfBirth() {
   return dateOfBirth;
 }
 public void setDateOfBirth(Date dateOfBirth) {
   this.dateOfBirth = dateOfBirth;
 }
 public long getId() {
   return id;
 }
 public void setId(long id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }
 
 

}</source>

Set Column Name For Accessor

File: Student.java

   <source lang="java">

import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Table; @Entity public class Student {

 private int id = 0;
 private String name;
 
 @Id
 @Column(name = "EMP_ID")
 public int getId() {
   return id;
 }
 public void setId(int id) {
   this.id = id;
 }
 public String getName() {
   return name;
 }
 public void setName(String name) {
   this.name = name;
 }
 public String toString() {
   return "\n\nID:" + id + "\nName:" + name + "\n\n";
 }

}</source>

Seven Entities

File: Address.java

   <source lang="java">

import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; @Entity public class Address implements java.io.Serializable {

 private int id;
 private String street;
 private String city;
 private String state;
 private String zip;
 @Id
 @GeneratedValue
 public int getId() {
   return id;
 }
 public void setId(int id) {
   this.id = id;
 }
 public String getStreet() {
   return street;
 }
 public void setStreet(String street) {
   this.street = street;
 }
 public String getCity() {
   return city;
 }
 public void setCity(String city) {
   this.city = city;
 }
 public String getState() {
   return state;
 }
 public void setState(String state) {
   this.state = state;
 }
 public String getZip() {
   return zip;
 }
 public void setZip(String zip) {
   this.zip = zip;
 }

}</source>