通过hibernate访问postgreSQL的搭建过程

Posted 2020-09-11 XD-Thinker

1. 环境:win7,Intellij IDEA
2. postgreSQL的安装:
   1. 安装包下载:https://www.postgresql.org/download/　去官网下载postgresql-9.1.3-1-windows.exe（46M）
   2. 傻瓜式安装,跟着安装引导走,一路next,用户名默认为 postgres,密码*****,端口默认5432
   3. 启动服务,打开services.msc,如果postgre没有启动则手动启动
3. postgreSQL客户的工具的安装:目前有多种客户工具,我用的是navicat for postgreSQL,去官网下载https://www.navicat.com/download/navicat-for-postgresql
   1. 解压压缩包,点击navicat.ext启动
   2. 双击连接->填写用户名,密码,端口,连接名,创建连接
   3. 右键点击连接名称,创建数据库
   4. 创建模式,(postgre的数据结构多了一层模式的结构,数据库>模式>表>字段),数据库创建时有默认的模式为public,右键数据库名,创建模式myschema
   5. 创建表,右键表,创建表,填写字段(user_id,username,password);
4. 搭建hibernate环境:
   1. 用Intellij 新建javaWeb项目
   2. 引入jar包:
      1. 　　hibernate jar包 在pom.xml写依赖:

         <!--hibernate--> <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core --> <dependency>   <groupId>org.hibernate</groupId>   <artifactId>hibernate-core</artifactId>   <version>5.1.2.Final</version> </dependency>

      2. postgreSQL jdbc jar包引入   在pom.xml中写依赖:

         <dependency>   <groupId>postgresql</groupId>   <artifactId>postgresql</artifactId>   <version>9.1-901-1.jdbc4</version> </dependency>

   3. 配置hibernate配置文件,项目由maven管理,在resources目录下加入hibernate.cfg.xml文件,该配置文件主要记录了数据库的有户名,ip,密码,端口,所用jdbc驱动等信息内容如下:

      <?xml version=‘1.0‘ encoding=‘utf-8‘?>
      <!DOCTYPE hibernate-configuration PUBLIC
              "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
              "src/resource/schema/hibernate-configuration-3.0.dtd">
      
      <hibernate-configuration>
      
          <session-factory>
              <!-- Database connection settings -->
              <!-- Database connection settings -->
              <property name="connection.driver_class">
                  org.postgresql.Driver
              </property>
              <property name="connection.url">
                  jdbc:postgresql://10.21.132.19:5432/test
              </property>
              <property name="connection.username">postgres</property>
              <property name="connection.password">88075998</property>
      
      
              <!-- JDBC connection pool (use the built-in) -->
              <property name="connection.pool_size">1</property>
      
              <!-- SQL dialect -->
              <property name="dialect">
                  org.hibernate.dialect.PostgreSQLDialect
              </property>
      
              <!-- Enable Hibernate‘s automatic session context management -->
              <property name="current_session_context_class">thread</property>
      
              <!-- Disable the second-level cache  
              <property name="cache.provider_class">
                  org.hibernate.cache.internal.NoCacheProvider
              </property>-->
      
              <!-- Echo all executed SQL to stdout -->
              <property name="show_sql">false</property>
      
              <!-- Drop and re-create the database schema on startup -->
              <!-- <property name="hbm2ddl.auto">update</property> -->
      
              <!-- <mapping resource="com/hik/gss/sys/domain/User.hbm.xml" />-->
              
              <mapping class="model.User"></mapping>
          </session-factory>
      
      </hibernate-configuration>

       

5. hibernate的查询语句,hibernate的操作有两种1.xml文件配置2.注解,这里用的是注解法,图个方便.
   1. 实体类的定义,如下:

      package model;
      
      import org.hibernate.annotations.GenericGenerator;
      
      import javax.persistence.*;
      
      @Entity
      @Table(name="public.user")
      public class User {
          private Integer userId;
          private String userName;
          private String passWord;
      
          @Id
          @GeneratedValue(generator="increment")
          @GenericGenerator(name="increment", strategy = "increment")
          @Column(name = "user_id")
          public Integer getUserId() {
              return userId;
          }
      
          public void setUserId(Integer userId) {
              this.userId = userId;
          }
      
          @Column(name = "username")
          public String getUserName() {
              return userName;
          }
      
          public void setUserName(String userName) {
              this.userName = userName;
          }
      
          @Column(name = "password")
          public String getPassWord() {
              return passWord;
          }
      
          public void setPassWord(String passWord) {
              this.passWord = passWord;
          }
      
      
      
      
      }

      
      注解说明:@Entity实体类标注,    @Table标注表名,注意表名前面要写模式名(public),被坑过.   @Id 表示主键   @Column列名  

   2. 查询数据库代码Demo:

              final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                      .configure()                 .build();
               SessionFactory sessionFactory = null;
              try {
                  sessionFactory = new MetadataSources( registry ).buildMetadata().buildSessionFactory();
              } catch (Exception e) {
                  // The registry would be destroyed by the SessionFactory, but we had trouble building the SessionFactory
                  // so destroy it manually.
                  StandardServiceRegistryBuilder.destroy( registry );
              }
      
              Session session = sessionFactory.openSession();
              session.beginTransaction();
              List result = session.createQuery( "from model.User" ).list();
              for ( User user : (List<User>) result ) {
                  System.out.println( "User (" + user.getUserName() + ") : " + user.getPassWord() );
                  if (this.passWord.equals(user.getPassWord()) && this.userName.equals(user.getUserName())) {
                      return "SUCCESS";
                  }
              }
              session.getTransaction().commit();
              session.close();

      
      总结一下查询的步骤:

      1. 注册
      2. 创建会话工厂
      3. 会话工厂生产会话
      4. 创建查询语句
      5. 会话执行查询语句
      6. 获取结果