之前两篇介绍了使用Hibernate生成SQL全量脚本文件的方式，若需要生成增量脚本进行版本维护呢？想到的对于生成增量脚本的方案可归为：
- 全量脚本文件与全量脚本文件对比生成
- 全量脚本文件与数据库对比生成
- 数据库与数据库对比生成
经过实际查询，第一种方案实现基本为零，暂未找到相关实现；第二种方案可以通过Hibernate的SchemaUpdate实现，也可以通过Liquibase实现；第三种方案可以通过Liquibase实现。
本次介绍通过Hibernate的SchemaUpdate生成SQL增脚本文件的方式，与SchemaExport生成全量脚本一样也可以通过两种方式生成。不同之处在于生成全量脚本时可以不配置数据库连接信息,，但生成增量脚本时必须配置数据库连接信息，从而连接数据库，不然只有程序中的注解，缺少参照的从而无法生成增量。
目录
单独main函数生成
这个和之前的SchemaExport一样，只是createData方法换成了updatData方法。之前说可能会产生报错提示的情况，当精确到类似路径时classpath*:**/**/entity/*.class（即所有含注解的class均在entity包中）即可避免。这里不再细谈，具体的注释可见之前的文章。
package com.windcoder.qycms.core.basis.test.Hibernate.ddl;
import org.hibernate.boot.MetadataSources;import org.hibernate.boot.registry.StandardServiceRegistry;import org.hibernate.boot.registry.StandardServiceRegistryBuilder;import org.hibernate.boot.spi.MetadataImplementor;import org.hibernate.dialect.Dialect;import org.hibernate.dialect.MySQL5InnoDBDialect;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.hibernate.tool.hbm2ddl.SchemaUpdate;import org.springframework.core.io.Resource;import org.springframework.core.io.support.PathMatchingResourcePatternResolver;import org.springframework.core.type.classreading.MetadataReader;import org.springframework.core.type.classreading.SimpleMetadataReaderFactory;import org.springframework.util.FileCopyUtils;import org.springframework.util.StreamUtils;import org.springframework.util.StringUtils;
import javax.persistence.Entity;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.lang.annotation.Annotation;import java.nio.charset.Charset;import java.text.SimpleDateFormat;import java.util.*;import java.util.stream.Collectors;
/** * 可以使用JPA Entity类生成DDL查询的类 * * 生成成功，但DIALECT_CLASS获取不友好。 * https://gist.github.com/sbcoba/e4264f4b4217746767e682c61f9dc3a6 */public class JpaEntityDdlExport { /** * 要创建的文件名 */ private static final String SCHEMA_UPDATE_SQL = "schema-update_%s.sql"; /** * 域类路径位置（如果范围很宽，则只能找到带有@Entity的类） */ private final static String PATTERN = "classpath*:**/**/entity/.class"; private final static String PATH = "com.windcoder";
/** * DB类型生成DDL * org.hibernate.dialect.* 包参考* * * - Oracle Oracle10gDialect.class * - H2 H2Dialect.class * ... * */ private final static Class<? extends Dialect> DIALECT_CLASS = MySQL5InnoDBDialect.class;
public static void main(String[] args) { updatData(args); }
/** * 生成全量SQL脚本 * @param args */ public static void updatData(String[] args){ File propsFile = new File("./qycms-core/common/src/main/resources/application.properties");
Properties properties = new Properties(); try { properties.load(new FileInputStream(propsFile)); Map<String, Object> settings = new HashMap<>(); settings.put("hibernate.dialect", DIALECT_CLASS); settings.put("hibernate.connection.driver", properties.getProperty("spring.datasource.driver-class-name")); settings.put("hibernate.connection.url", properties.getProperty("spring.datasource.url")); settings.put("hibernate.connection.username", properties.getProperty("spring.datasource.username")); settings.put("hibernate.connection.password", properties.getProperty("spring.datasource.password")); settings.put("hibernate.physical_naming_strategy","org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy"); settings.put("hibernate.implicit_naming_strategy","org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy"); settings.put("hibernate.id.new_generator_mappings", false);
StandardServiceRegistry standardServiceRegistry = new StandardServiceRegistryBuilder() .applySettings(settings) .build();
MetadataSources metadata = new MetadataSources(standardServiceRegistry); String pattern = getPattern(args); List<Class<?>> classes = getClassesByAnnotation(Entity.class, pattern); classes.forEach(metadata::addAnnotatedClass); MetadataImplementor metadataImplementor = (MetadataImplementor) metadata.getMetadataBuilder().build(); SchemaUpdate schemaUpdate = new SchemaUpdate(metadataImplementor); schemaUpdate.setOutputFile(getOutputFilename(args));
schemaUpdate.setDelimiter(";"); schemaUpdate.setFormat(false); schemaUpdate.execute(true, false); } catch (IOException e) { e.printStackTrace(); } }
private static String getPattern(String[] args) { String pattern = PATTERN; if(args != null && args.length >= 3 && StringUtils.hasText(args[2])) { pattern = args[2]; } return pattern; }
private static void appendMetaData(String outputFile, Map<String, Object> settings) { String charsetName = "UTF-8"; File ddlFile = new File(outputFile); try { StringBuilder sb = new StringBuilder(); sb.append("/* Generate Environment\n"); for (Map.Entry<String, Object> entry : settings.entrySet()) { sb.append(entry.getKey().toString() + ": " + entry.getValue() + "\n"); } sb.append("*/\n"); String ddlFileContents = StreamUtils.copyToString(new FileInputStream(ddlFile), Charset.forName(charsetName)); sb.append(ddlFileContents); FileCopyUtils.copy(sb.toString().getBytes(charsetName), ddlFile); } catch (IOException e) { e.printStackTrace(); } }
private static List<Class<?>> getClassesByAnnotation(Class<? extends Annotation> annotation, String pattern) { return getResources(pattern).stream() .map(r -> metadataReader(r)) .filter(Objects::nonNull) .filter(mr -> mr.getAnnotationMetadata().hasAnnotation(annotation.getName())) .map(mr -> entityClass(mr)) .filter(Objects::nonNull) .collect(Collectors.toList()); }
/** * 获取与模式对应的资源信息。 * @param pattern * @return */ private static List<Resource> getResources(String pattern) { PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(); Resource[] resources; try { resources = resolver.getResources(pattern); } catch (IOException e) { throw new RuntimeException(e); } return Arrays.asList(resources); }
private static Class<?> entityClass(MetadataReader mr) { String className = mr.getClassMetadata().getClassName(); Class<?> clazz; try { clazz = Class.forName(className); } catch (ClassNotFoundException e) { System.err.printf("%s Class not found", className); return null; } return clazz; }
private static MetadataReader metadataReader(Resource r) { MetadataReader mr; try { mr = new SimpleMetadataReaderFactory().getMetadataReader(r); } catch (IOException e) { System.err.printf(e.getMessage()); return null; } return mr; }
private static String getOutputFilename(String[] args) { SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss"); String currentDate = sdf.format(Calendar.getInstance().getTime()); if(args != null && args.length > 0 && StringUtils.hasText(args[0])) { String customSchemaName = args[0]; if(customSchemaName.contains("%s")) { return String.format(customSchemaName, currentDate); } return customSchemaName; } return String.format(SCHEMA_UPDATE_SQL, currentDate); }}构建项目期间生成
这个和之前创建全量脚本的类似，区别之处是全量脚本的StandardServiceRegistry是通过StandardServiceRegistryBuilder直接创建的，增量的是通过
LocalContainerEntityManagerFactoryBean->EntityManagerFactoryImpl(由getNativeEntityManagerFactory()强转得到)->SessionFactoryImpl(由getSessionFactory()强转得到)->StandardServiceRegistry（由getSessionFactoryOptions().getServiceRegistry()得到）完整文件如下：
package com.windcoder.qycms.core.basis.test.Hibernate.ddl;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.spi.MetadataImplementor;
import org.hibernate.internal.SessionFactoryImpl;import org.hibernate.jpa.internal.EntityManagerFactoryImpl;
import org.hibernate.tool.hbm2ddl.SchemaUpdate;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.ApplicationArguments;import org.springframework.boot.ApplicationRunner;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import org.springframework.stereotype.Component;
import java.text.SimpleDateFormat;import java.util.Calendar;
import java.util.List;
/** * 参考资料： * https://stackoverflow.com/questions/34612019/programmatic-schemaexport-schemaupdate-with-hibernate-5-and-spring-4 */@Componentpublic class JPASchemaSchemaUpdate implements ApplicationRunner { private static final String SCHEMA_SQL2 = "db/base/update-ddl_2_%s.sql";
@Autowired LocalContainerEntityManagerFactoryBean fb;
@Override public void run(ApplicationArguments args) throws Exception {
EntityManagerFactoryImpl emf=(EntityManagerFactoryImpl)fb.getNativeEntityManagerFactory();
SessionFactoryImpl sf= (SessionFactoryImpl) emf.getSessionFactory(); StandardServiceRegistry serviceRegistry = sf.getSessionFactoryOptions().getServiceRegistry(); MetadataSources metadata = new MetadataSources(serviceRegistry); List<String> managedClassNames = fb.getPersistenceUnitInfo().getManagedClassNames(); for (String managedClassName : managedClassNames) { metadata.addAnnotatedClassName(managedClassName); } MetadataImplementor metadataImplementor = (MetadataImplementor) metadata.getMetadataBuilder().build();
SchemaUpdate schemaUpdate = new SchemaUpdate(metadataImplementor);
schemaUpdate.setOutputFile(getOutputFilename());
schemaUpdate.setDelimiter(";"); schemaUpdate.setFormat(false); schemaUpdate.execute(true, false);
}
private static String getOutputFilename() { SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss"); String currentDate = sdf.format(Calendar.getInstance().getTime());
return String.format(SCHEMA_SQL2, currentDate); }
}
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