Configure IP for server access using Hibernate

Question

I have a Java application that uses Hibernate, for development I made the database configuration using localhost but for use on other computers I will need to define the IP that will have the database (Server) in my project I use the file Persistence.xml

I thought through a home screen, the user register the IP of the machine in a configuration file created in the installation.

But now I come across the situation of having to inform to Persistence which IP informed in the file created by the installation process.

Follow the example of my Persistence below.

<?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/persistence/persistence_1_0.xsd">
<persistence-unit name="ConexaoPU" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>br.com.exemplo.modelo.Exemplovenda</class>
<properties>
  <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/conexao?zeroDateTimeBehavior=convertToNull"/>
  <property name="javax.persistence.jdbc.password" value="root"/>
  <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
  <property name="javax.persistence.jdbc.user" value="root"/>
  <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/>
  <property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>

Answer 1

If I understood the question correctly I went through a similar situation some time ago. In the case the solution I used was the following:

• Create a map with different file properties persistence.xml, in your case, the database IP; and
• Move that map to the function createEntityManagerFactory() that will use the file properties persistence.xml and will replace only those you set on the map.

Example:

Map map = new HashMap();
map.put("javax.persistence.jdbc.url", "uma URL informado pelo usuário"); //Essa propriedade vai substituir aquela que está no arquivo.

EntityManagerFactory emf = javax.persistence.Persistence.createEntityManagerFactory("ConexaoPU",mapa);
EntityManager em = emf.createEntityManager();

Of course if the user typed only the IP you will have to handle the URL, for example:

String ip = "192.168.0.0:3306"; //Algum IP e porta informado pelo usuário
String url = "jdbc:mysql:" + ip + "/caminho para arquivo";

Answer 2

First Option

You can pass during the creation of EntityManagerFactory a properties file obtained in your classpath as an example below:

Properties p = new Properties();

p.load(new FileInputStream("um/caminho/no/seu/classpath/persistence.properties"));

// ajuste detalhes que não deseja expor no arquivo de propriedades.

EntityManagerFactory factory = Persistence.createEntityManagerFactory("unitAppName", p);

If you need to inform the authentication data you can encrypt the file and decrypt it internally after loading it and before using it.

Second Option

If you are not informing which entities are in your file persistence.xml, you can create a new file with the custom parameters as per your installation, this file must be in the classpath of your application, in addition if you need further protection, you can protect this file in an encrypted Jar file, but you will need to register a specialized classloader to decrypt it.