连接到 mySQL、JPA、Java EE 和 JBoss

Question

I'm trying to connect to mySQL database using JPA and hibernate implementation but it doesn't create the tables in the database even though in the logs it appears it's creating it. Here is my pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>academy.learnprogrammin</groupId>
<artifactId>hello-javaee8</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>8.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.wildfly</groupId>
        <artifactId>wildfly-ejb-client-bom</artifactId>
        <type>pom</type>
        <version>9.0.1.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate.javax.persistence</groupId>
        <artifactId>hibernate-jpa-2.1-api</artifactId>
        <version>1.0.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.5.Final</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.23</version>
    </dependency>
</dependencies>
<build>
    <finalName>hello-javaee8</finalName>
    <plugins>
        <!-- The WildFly plug-in deploys the WAR to a local JBoss EAP container -->
        <!-- To use, run: mvn package wildfly:deploy -->
        <plugin>
            <groupId>org.wildfly.plugins</groupId>
            <artifactId>wildfly-maven-plugin</artifactId>
            <version>1.0.2.Final</version>
        </plugin>
    </plugins>
</build>
<properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <failOnMissingWebXml>false</failOnMissingWebXml>
</properties>

And persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence 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_2_0.xsd"
    version="2.0">
    <persistence-unit name="studentsApp" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/students" />
            <property name="javax.persistence.jdbc.user" value="students" />
            <property name="javax.persistence.jdbc.password" value="admissssn" />
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="false" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
            <property name="hibernate.hbm2ddl.auto" value="create" />
        </properties>
    </persistence-unit>
</persistence>

And Student entity class:

package com.learning.entity;

import javax.annotation.Generated;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "students_data")
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    
    private String name;
    
    public Student() {
    }
    
    public Student(long id, String name) {
        this.id = id;
        this.name = 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;
    }
}

And this is my project structure:

Here's the server console where it logs creating the students_data table:

12:02:13,074 INFO  [stdout] (ServerService Thread Pool -- 205) Hibernate: create table students_data (id bigint not null auto_increment, name varchar(255), primary key (id)) engine=InnoDB

I'm deploying to JBoss EAP 7.0 with wildfly mvn plugin.

There is another strange behaviour that I changed the database credentials to something wrong (wrong username, password) it doesn't give error and logs still saying the table is created.

Answer 1

Couple of suggestions from my experience at different times,

1. Not completely sure of the internals, but at times depending on how the configuration is set, the long form and the short form of the property tag makes some mess.

From

    <property name="hibernate.hbm2ddl.auto" value="create"/>

To:

     <property name="hibernate.hbm2ddl.auto">create</property>

2. Having this property, makes it working at times,

    <property name="javax.persistence.schema-generation.database.action" value="drop-and-create" />

Use values as

a) create: The provider will create the database artifacts on application deployment. The artifacts will remain unchanged after application redeployment.

b) drop-and-create: Any artifacts in the database will be deleted, and the provider will create the database artifacts on deployment.

More details: https://docs.oracle.com/javaee/7/tutorial/persistence-intro005.htm