我如何从Java代码为我的jpa实体创建一个ddl？ [英] How can I create a ddl for my jpa entities from java code?

问题描述

我寻找一种方法，可以为我的jpa注释实体创建一个ddl。
我更喜欢纯java方式。

如果可能的话，生成drop语句也会很好。

从数据库导出数据为sql 使用 href =http://www.liquibase.org/ =nofollow noreferrer> liquibase opensource project

LiquiBase是一个开放源码（LGPL），与数据库无关的库，用于跟踪，管理和应用数据库更改。它建立在一个简单的前提上：所有数据库更改（结构和数据）都以基于XML的描述性方式进行存储并签入源代码管理。

为给定的JPA实体生成创建和删除脚本

我们使用这段代码来生成drop和create语句：
只需用所有的实体类构造这个类并调用create / dropTableScript即可。

需要您可以使用persitence.xml和persistence单元名称。只要说一些
并发布代码即可。

 
 import java.util.Collection; 
 import java.util.Properties; 
 
 import org.hibernate.cfg.AnnotationConfiguration; 
 import org.hibernate.dialect.Dialect; 
 import org.hibernate.ejb.Ejb3Configuration; 
 
 / ** 
 *根据JPA / Hibernate注释的SQL Creator for Tables。 
 * 
 *使用：
 * 
 * {@link #createTablesScript（）}创建表creationg脚本
 * 
 * {@link＃ dropTablesScript（）}创建表破坏脚本
 * 
 * / 
 public class SqlTableCreator {
 
 private final AnnotationConfiguration hibernateConfiguration; 
 private final属性dialectProps; 
 
 public SqlTableCreator（final Collection> entities）{
 
 final Ejb3Configuration ejb3Configuration = new Ejb3Configuration（）; 
 for（final Class entity：entities）{
 ejb3Configuration.addAnnotatedClass（entity）; 
} 
 
 dialectProps = new Properties（）; 
 dialectProps.put（hibernate.dialect，org.hibernate.dialect.SQLServerDialect）; 
 
 hibernateConfiguration = ejb3Configuration.getHibernateConfiguration（）; 
} 
 
 / ** 
 *创建SQL脚本来创建所有表。 
 * 
 * @return代表SQL脚本的{@link String}。 
 * / 
 public String createTablesScript（）{
 final StringBuilder script = new StringBuilder（）; 
 
 final String [] creationScript = hibernateConfiguration.generateSchemaCreationScript（dialect 
 .getDialect（dialectProps））; 
 for（final String string：creationScript）{
 script.append（string）.append（; \\\
）; 
} 
 script.append（\\\
go\\\
\\\
）; 
 
 return script.toString（）; 
} 
 
 / ** 
 *创建SQL脚本以删除所有表。 
 * 
 * @return代表SQL脚本的{@link String}。 
 * / 
 public String dropTablesScript（）{
 final StringBuilder script = new StringBuilder（）; 
 
 final String [] creationScript = hibernateConfiguration.generateDropSchemaScript（方言
 .getDialect（dialectProps））; 
 for（final String string：creationScript）{
 script.append（string）.append（; \\\
）; 
} 
 script.append（\\\
go\\\
\\\
）; 
 
 return script.toString（）; 
} 
} 
 
 

I look for a way how I can create a ddl for my jpa annotated entities. I prefer a pure java way for this.

If possible it would be nice to have generate the drop statements too.

解决方案

Export data from a database as sql

Use the liquibase opensource project

LiquiBase is an open source (LGPL), database-independent library for tracking, managing and applying database changes. It is built on a simple premise: All database changes (structure and data) are stored in an XML-based descriptive manner and checked into source control.

Generate create and drop script for given JPA entities

We use this code to generate the drop and create statements: Just construct this class with all entity classes and call create/dropTableScript.

If needed you can use a persitence.xml and persitance unit name instead. Just say something and I post the code too.

import java.util.Collection;
import java.util.Properties;

import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.dialect.Dialect;
import org.hibernate.ejb.Ejb3Configuration;

/**
 * SQL Creator for Tables according to JPA/Hibernate annotations.
 *
 * Use:
 *
 * {@link #createTablesScript()} To create the table creationg script
 *
 * {@link #dropTablesScript()} to create the table destruction script
 * 
 */
public class SqlTableCreator {

    private final AnnotationConfiguration hibernateConfiguration;
    private final Properties dialectProps;

    public SqlTableCreator(final Collection> entities) {

        final Ejb3Configuration ejb3Configuration = new Ejb3Configuration();
        for (final Class entity : entities) {
            ejb3Configuration.addAnnotatedClass(entity);
        }

        dialectProps = new Properties();
        dialectProps.put("hibernate.dialect", "org.hibernate.dialect.SQLServerDialect");

        hibernateConfiguration = ejb3Configuration.getHibernateConfiguration();
    }

    /**
     * Create the SQL script to create all tables.
     * 
     * @return A {@link String} representing the SQL script.
     */
    public String createTablesScript() {
        final StringBuilder script = new StringBuilder();

        final String[] creationScript = hibernateConfiguration.generateSchemaCreationScript(Dialect
                .getDialect(dialectProps));
        for (final String string : creationScript) {
            script.append(string).append(";\n");
        }
        script.append("\ngo\n\n");

        return script.toString();
    }

    /**
     * Create the SQL script to drop all tables.
     * 
     * @return A {@link String} representing the SQL script.
     */
    public String dropTablesScript() {
        final StringBuilder script = new StringBuilder();

        final String[] creationScript = hibernateConfiguration.generateDropSchemaScript(Dialect
                .getDialect(dialectProps));
        for (final String string : creationScript) {
            script.append(string).append(";\n");
        }
        script.append("\ngo\n\n");

        return script.toString();
    }
}

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