Intellij IDEA的Hibernate简单应用

ゝ一纸荒年。 2022-06-10 19:58 130阅读 0赞

# Intellij IDEA的Hibernate简单应用 #

## Intellij IDEA连接数据库 ##

1）点击IDEA主界面右边的Database，点击“+”号，选择Data Source -> 选择对应的数据库，我这里选择的是MySQL。  
2）输入需要用到的数据库的名称，比如demo，输入用户名和密码，点击“Test Connection‘，测试连接数据库是否成功。

3）数据库连接成功，点击”OK“，最后点击”Apply“和”OK“即可。

如下图：

![Center][]

## 添加依赖 ##

在pom.xml中添加如下内容

<dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.2.10.Final</version>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>6.0.4</version>
        </dependency>

## 配置 ##

在项目名称上，右键添加Add Framework Support,左侧勾选Hibernate，然后ok即可  
菜单栏View-->Tool Window-->Persistence,打开Persistence。  
在Persistence model项目上右键，Generate Persistence Mapping-->By Database Schema,  
配置生成数据库实体类，具体配置如下

![Center 1][]

说明：

hibernate.cfg.xml文件如果生成的路径不对，则把该文件移到 src-main-resources下，生成的内容不全，完整内容如下：

<?xml version='1.0' encoding='utf-8'?>
    <!DOCTYPE hibernate-configuration PUBLIC
            "-//Hibernate/Hibernate Configuration DTD//EN"
            "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
        <session-factory>
    
            
            <property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
            
            <property name="connection.url">jdbc:mysql://localhost:3306/news?serverTimezone=UTC</property>
            
            
            <property name="connection.username">root</property>
            <property name="connection.password"></property>
            
            <property name="connection.characterEncoding">utf8</property>
            
            <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
            
            <property name="show_sql">true</property>
            
            <property name="format_sql">true</property>
            
            <property name="hbm2ddl.auto">update</property>
    
            
            <mapping resource="mapping/t_sound.hbm.xml"/>
            <mapping class="com.lfb.model.entity.TSoundEntity"/>
        </session-factory>
    </hibernate-configuration>

<property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
            
            <property name="connection.url">jdbc:mysql://localhost:3306/news?serverTimezone=UTC</property>

这两项生成的原来内容不是这样，因为出错才改成这样。

原内容是这样的

<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            
            <property name="connection.url">jdbc:mysql://localhost:3306/news</property>

不改运行时会报如下的错误

1、Loading class \`com.mysql.jdbc.Driver'.This isdeprecated. The new driver class is \`com.mysql.cj.jdbc.Driver。  
按照书上的教程，写了如下的数据库连接配置：  
user=root    
password=    
driverClass=com.mysql.jdbc.Driver    
jdbcUrl=jdbc:mysql://localhost:3306/news    
以上配置中，密码我是默认没有设置的。在连接的时候出现以上提示，根据提示，很显然，这种driver配置方式在此版本中已经被废弃，因此需要将driverClass配置为：com.mysql.cj.jdbc.Driver。  
  
  
2、如下提示：  
警告: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@1a0e2e48 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!  
xxxxx com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run  
警告: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@1a0e2e48 -- APPARENT DEADLOCK!!! Complete Status:   
...  
java.sql.SQLException: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.  
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:695)  
搜索了一下 需要在Url后面添加一个参数：  
?serverTimezone=UTC

## 添加db操作类 Sound.java ##

package com.lfb.bll;
    
    import com.lfb.model.entity.TSoundEntity;
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.Transaction;
    import org.hibernate.cfg.Configuration;
    
    /**
     * Created by xxx on 2017/8/1.
     */
    public class Sound {
        public  void Add(){
            // 加载Hibernate默认配置文件
            Configuration configuration = new Configuration().configure();
            // 用Configuration创建SessionFactory
            SessionFactory sessionFactory = configuration.buildSessionFactory();
            // 创建Session
            Session session = sessionFactory.openSession();
            // 开启事务
            Transaction transaction = session.beginTransaction();
            // 实例化持久化类
            TSoundEntity sound = new TSoundEntity();
            sound.setId(1);
            sound.setTitle("万里长城永不倒");
    
            // 保存
            session.save(sound);
            // 提交事务
            transaction.commit();
            // 关闭Session，释放资源
            session.close();
            sessionFactory.close();
        }
    }

## 在入口函数main里加入测试入口 ##

Sound bll = new Sound();
    bll.Add();

启动测试，发现数据写入到了db，其它的db操作后续补充

上面是bibernate + mysql的例子，下面列出hibernate + sqlserver的不同之处

## hibernate + sqlserver 与mysql 的不同之处 ##

### 1 sqlserver 依赖 ###

<dependency>
                <groupId>com.microsoft.sqlserver</groupId>
                <artifactId>mssql-jdbc</artifactId>
                <version>6.1.0.jre8</version>
            </dependency>

### 2 hibernate.cfg.xml ###

<?xml version='1.0' encoding='utf-8'?>
    <!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
      <session-factory>
        <property name="connection.url">jdbc:sqlserver://192.168.1.1:3341;databaseName=News</property>
        <property name="connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
        
        
        <property name="connection.username">test</property>
        <property name="connection.password">test</property>
        
        <property name="hibernate.dialect">org.hibernate.dialect.SQLServer2008Dialect</property>
        
        <property name="show_sql">true</property>
        
        <property name="format_sql">true</property>
        
        <property name="hbm2ddl.auto">update</property>
    
        
        <mapping resource="mapping/t_city.hbm.xml"/>
        <mapping class="com.lfb.model.entity.TCityEntity"/>
      </session-factory>
    </hibernate-configuration>

3 映射类中的自增列问题

package com.lfb.model.entity;
    
    /**
     * Created by xxx on 2017/8/2.
     */
    public class TCityEntity {
        private int id;
        private String name;
        private int parentId;
        private int sort;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public int getParentId() {
            return parentId;
        }
    
        public void setParentId(int parentId) {
            this.parentId = parentId;
        }
    
        public int getSort() {
            return sort;
        }
    
        public void setSort(int sort) {
            this.sort = sort;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
    
            TCityEntity that = (TCityEntity) o;
    
            if (id != that.id) return false;
            if (parentId != that.parentId) return false;
            if (sort != that.sort) return false;
            if (name != null ? !name.equals(that.name) : that.name != null) return false;
    
            return true;
        }
    
        @Override
        public int hashCode() {
            int result = id;
            result = 31 * result + (name != null ? name.hashCode() : 0);
            result = 31 * result + parentId;
            result = 31 * result + sort;
            return result;
        }
    }

t\_city.hbm.xml

<?xml version='1.0' encoding='utf-8'?>
    <!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
    
        <class name="com.lfb.model.entity.TCityEntity" table="T_City" schema="dbo" catalog="Lifobao_Core">
            <id name="id">
                <column name="Id" sql-type="int"/>
                <generator class="native" />
            </id>
            <property name="name">
                <column name="Name" sql-type="nvarchar(50)" length="50"/>
            </property>
            <property name="parentId">
                <column name="ParentId" sql-type="int"/>
            </property>
            <property name="sort">
                <column name="Sort" sql-type="int"/>
            </property>
        </class>
    </hibernate-mapping>

注意id列的下面加了

这个，

其它同mysql一样，

\--- end ---

[Center]: /images/20220611/d5d515cbc5ce4085ab11dc10f6463f46.png
[Center 1]: /images/20220611/fdedb8a2415d43bc8c1c30b748123486.png