达梦数据库整合流程,mybatis-plus踩坑记录

达梦数据库整合流程,mybatis-plus踩坑记录

从mysql迁移到达梦数据库可以使用达梦的迁移工具进行迁移,具体可以参考

https://www.cnblogs.com/zywu-king/p/12337382.html 这篇文章;

本次项目使用主要架构为

  • mybatis-plus 3.14
  • 达梦数据库版本8

数据库驱动问题

使用数据库驱动如下

<dependency>
  <groupId>com.dameng</groupId>
  <artifactId>Dm8JdbcDriver18</artifactId>
  <version>8.1.1.49</version>
</dependency>

注意点 : DmJdbcDriver18 这类依赖不能使用,否则mybatis 查询数据库会出现类型转换错误;其次 达梦版本为8 就使用 Dm8JdbcDriver18, 如果达梦版本为7 ,就使用 Dm7JdbcDriver17 以此类推;

如果使用 jpa 那么 达梦8 对应的 hibernate 依赖如下

<dependency>
  <groupId>com.dameng</groupId>
  <artifactId>DmDialect-for-hibernate4.0</artifactId>
  <version>8.1.2.79</version>
</dependency>

附方言配置(按需配置)

#方言
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.DmDialect
spring.jpa.database-platform=org.hibernate.dialect.DmDialect
spring.jpa.properties.hibernate.hbm2ddl.auto=update
spring.jpa.properties.hibernate.show_sql=true

spring配置文件问题

达梦数据库类似oracl,其数据库方式为模式方式。一个模式就是一个数据库;如果数据库名称和模式名称不一致,那么使用类似原始的数据库url 就会出问题, 谨慎起见,url后面都配置模式名称;

错误示范

url: jdbc:dm://localhost:5236/mydb

正确示范

url: jdbc:dm://localhost:5236?schema=mydb

mysql 有 longtext, text blog 等大数据库类型,迁移到达梦数据库 一般会转为clob 类型;查询时会报类型转换异常在url后面添加配置,将 clob当作 string处理;

&clobAsString=true

完整的JDBC连接

          url: jdbc:dm://localhost:5236?schema=mydb&compatibleMode=mysql&characterEncoding=UTF-8&useUnicode=true&useSSL=false&tinyInt1isBit=false&allowPublicKeyRetrieval=true&serverTimezone=Asia/Shanghai
          username: SYSDBA
          password: mypassword
          driver-class-name: dm.jdbc.driver.DmDriver

activiti支持达梦数据库

方案一: 寻找已经整合好的jar包 ; 获取方式 关注gong众号知识追寻者:回复 dm 获取;

方案二: 将activiti-engine-5.22.0相关源码拷贝到工程src下,保持包路径不变,并做相应修改;

具体如下:

  1. 在org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl,增加成员变量
public static final String DATABASE_TYPE_DM = "dm";
public static final String DATABASE_TYPE_H2 = "h2";
public static final String DATABASE_TYPE_HSQL = "hsql";
public static final String DATABASE_TYPE_MYSQL = "mysql";
public static final String DATABASE_TYPE_ORACLE = "oracle";
  1. 在org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl,修改getDefaultDatabaseTypeMappings()
protected static Properties getDefaultDatabaseTypeMappings() {
    Properties databaseTypeMappings = new Properties();
    databaseTypeMappings.setProperty("DM DBMS", DATABASE_TYPE_DM);
    databaseTypeMappings.setProperty("H2", DATABASE_TYPE_H2);
  1. 在org.activiti.engine.impl.db.DbSqlSessionFactory,修改initBulkInsertEnabledMap(String databaseType)
if ("oracle".equals(databaseType) || "dm".equals(databaseType)) {
    bulkInsertableMap.put(EventLogEntryEntity.class, Boolean.FALSE);
}
  1. 在org.activiti.engine.impl.db.DbSqlSessionFactory,修改static{}
// dm
databaseSpecificLimitBeforeStatements.put("dm", "");
databaseSpecificLimitAfterStatements.put("dm", "LIMIT #{maxResults} OFFSET #{firstResult}");
databaseSpecificLimitBetweenStatements.put("dm", "");
databaseOuterJoinLimitBetweenStatements.put("dm", "");
databaseSpecificOrderByStatements.put("dm", defaultOrderBy);

// h2
databaseSpecificLimitBeforeStatements.put("h2", "");
databaseSpecificLimitAfterStatements.put("h2", "LIMIT #{maxResults} OFFSET #{firstResult}");
databaseSpecificLimitBetweenStatements.put("h2", "");
databaseOuterJoinLimitBetweenStatements.put("h2", "");
databaseSpecificOrderByStatements.put("h2", defaultOrderBy);
  1. 在 org.activiti.engine.impl.AbstractQuery,修改addOrder(String column, String sortOrder, NullHandlingOnOrder nullHandlingOnOrder)
if (nullHandlingOnOrder.equals(NullHandlingOnOrder.NULLS_FIRST)) {

    if (ProcessEngineConfigurationImpl.DATABASE_TYPE_H2.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_HSQL.equals(databaseType)
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_POSTGRES.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_ORACLE.equals(databaseType)
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_DM.equals(databaseType)) {
        orderBy = orderBy + defaultOrderByClause + " NULLS FIRST";
    } else if (ProcessEngineConfigurationImpl.DATABASE_TYPE_MYSQL.equals(databaseType)) {
        orderBy = orderBy + "isnull(" + column + ") desc," + defaultOrderByClause;
    } else if (ProcessEngineConfigurationImpl.DATABASE_TYPE_DB2.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_MSSQL.equals(databaseType)) {
        orderBy = orderBy + "case when " + column + " is null then 0 else 1 end," + defaultOrderByClause;
    } else {
        orderBy = orderBy + defaultOrderByClause;
    }

} else if (nullHandlingOnOrder.equals(NullHandlingOnOrder.NULLS_LAST)) {

    if (ProcessEngineConfigurationImpl.DATABASE_TYPE_H2.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_HSQL.equals(databaseType)
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_POSTGRES.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_ORACLE.equals(databaseType)
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_DM.equals(databaseType)) {
        orderBy = orderBy + column + " " + sortOrder + " NULLS LAST";
    } else if (ProcessEngineConfigurationImpl.DATABASE_TYPE_MYSQL.equals(databaseType)) {
        orderBy = orderBy + "isnull(" + column + ") asc," + defaultOrderByClause;
    } else if (ProcessEngineConfigurationImpl.DATABASE_TYPE_DB2.equals(databaseType) 
            || ProcessEngineConfigurationImpl.DATABASE_TYPE_MSSQL.equals(databaseType)) {
        orderBy = orderBy + "case when " + column + " is null then 1 else 0 end," + defaultOrderByClause;
    } else {
        orderBy = orderBy + defaultOrderByClause;
    }
}

同时需要引入外部依赖支持流程引擎

  <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
            <version>1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.enterprise.concurrent</groupId>
            <artifactId>javax.enterprise.concurrent-api</artifactId>
            <version>1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy-all</artifactId>
            <version>2.4.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.drools</groupId>
            <artifactId>drools-core</artifactId>
            <version>5.5.0.Final</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.drools</groupId>
            <artifactId>drools-compiler</artifactId>
            <version>5.5.0.Final</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.uuid</groupId>
            <artifactId>java-uuid-generator</artifactId>
            <version>3.1.3</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.transaction</groupId>
            <artifactId>javax.transaction-api</artifactId>
            <version>1.2</version>
            <scope>provided</scope>
        </dependency>

删除源码 test 包内容;

完成以上重新编译

数据库手册,达梦数据库连接工具统一关注 gong众号知识追寻者:回复 dm 获取;

参考连接 https://my.oschina.net/168052730/blog/4300003

posted @ 2022-04-02 10:40  知识追寻者  阅读(3309)  评论(0编辑  收藏  举报