Java Tutorial/JPA/Introduction

Field Injection ID

File: Student.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;
  }
}

JPA Development Environment Setup

File: Helper.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");
        }
      }
    }
  }
}

Mark Class As Entity

File: Student.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;
  }
}

Mark Property Accessor

File: Student.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";
  }
}

Persistance Configuration

File: Student.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;
  }
  
  
}

Set Column Name For Accessor

File: Student.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";
  }
}

Seven Entities

File: Address.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;
  }
}