Java的Spring框架中DAO数据访问对象的使用示例

spring dao之jdbc
 
spring提供的dao(数据访问对象)支持主要的目的是便于以标准的方式使用不同的数据访问技术， 如jdbc，hibernate或者jdo等。它不仅可以让你方便地在这些持久化技术间切换， 而且让你在编码的时候不用考虑处理各种技术中特定的异常。
为了便于以一种一致的方式使用各种数据访问技术，如jdbc、jdo和hibernate， spring提供了一套抽象dao类供你扩展。这些抽象类提供了一些方法，通过它们你可以 获得与你当前使用的数据访问技术相关的数据源和其他配置信息。
dao支持类：
jdbcdaosupport - jdbc数据访问对象的基类。 需要一个datasource，同时为子类提供 jdbctemplate。
hibernatedaosupport - hibernate数据访问对象的基类。 需要一个sessionfactory，同时为子类提供 hibernatetemplate。也可以选择直接通过 提供一个hibernatetemplate来初始化， 这样就可以重用后者的设置，例如sessionfactory， flush模式，异常翻译器（exception translator）等等。
jdodaosupport - jdo数据访问对象的基类。 需要设置一个persistencemanagerfactory， 同时为子类提供jdotemplate。 
jpadaosupport - jpa数据访问对象的基类。 需要一个entitymanagerfactory，同时 为子类提供jpatemplate。 
本节主要讨论sping对jdbcdaosupport的支持。
下面是个例子：

drop table if exists user; 

/*==============================================================*/ 
/* table: user                         */ 
/*==============================================================*/ 
create table user 
( 
  id          bigint auto_increment not null, 
  name         varchar(24), 
  age         int, 
  primary key (id) 
);

 

public class user { 
  private integer id; 
  private string name; 
  private integer age; 

  public integer getid() { 
    return id; 
  } 

  public void setid(integer id) { 
    this.id = id; 
  } 

  public string getname() { 
    return name; 
  } 

  public void setname(string name) { 
    this.name = name; 
  } 

  public integer getage() { 
    return age; 
  } 

  public void setage(integer age) { 
    this.age = age; 
  } 
}

 

/** 
* created by intellij idea.<br> 
* <b>user</b>: leizhimin<br> 
* <b>date</b>: 2008-4-22 15:34:36<br> 
* <b>note</b>: dao接口 
*/ 
public interface iuserdao { 
  public void insert(user user); 

  public user find(integer id); 
}
 
 
import javax.sql.datasource; 
import java.sql.connection; 
import java.sql.sqlexception; 

/** 
* created by intellij idea.<br> 
* <b>note</b>: 基类dao，提供了数据源注入 
*/ 
public class basedao { 
  private datasource datasource; 

  public datasource getdatasource() { 
    return datasource; 
  } 

  public void setdatasource(datasource datasource) { 
    this.datasource = datasource; 
  } 

  public connection getconnection() { 
    connection conn = null; 
    try { 
      conn = datasource.getconnection(); 
    } catch (sqlexception e) { 
      e.printstacktrace(); 
    } 
    return conn; 
  } 
}
 
 
/** 
* created by intellij idea.<br> 
* <b>user</b>: leizhimin<br> 
* <b>date</b>: 2008-4-22 15:36:04<br> 
* <b>note</b>: dao实现 
*/ 
public class userdao extends basedao implements iuserdao { 

  public jdbctemplate getjdbctemplate(){ 
    return new jdbctemplate(getdatasource()); 
  } 
  public void insert(user user) { 
    string name = user.getname(); 
    int age = user.getage().intvalue(); 

//    jdbctemplate.update("insert into user (name,age) " 
//        + "values('" + name + "'," + age + ")"); 

    string sql = "insert into user(name,age) values(?,?)"; 
    getjdbctemplate().update(sql,new object[]{name,age}); 
  } 

  public user find(integer id) { 
    list rows = getjdbctemplate().queryforlist( 
        "select * from user where id=" + id.intvalue()); 

    iterator it = rows.iterator(); 
    if (it.hasnext()) { 
      map usermap = (map) it.next(); 
      integer i = new integer(usermap.get("id").tostring()); 
      string name = usermap.get("name").tostring(); 
      integer age = new integer(usermap.get("age").tostring()); 

      user user = new user(); 

      user.setid(i); 
      user.setname(name); 
      user.setage(age); 

      return user; 
    } 
    return null; 
  } 
}

 

<?xml version="1.0" encoding="utf-8"?> 
<!doctype beans public "-//spring/dtd bean/en" 
    "http://www.springframework.org/dtd/spring-beans.dtd"> 

<beans> 
  <bean id="datasource" 
     class="org.apache.commons.dbcp.basicdatasource" singleton="true"> 
    <property name="driverclassname"> 
      <value>com.mysql.jdbc.driver</value> 
    </property> 
    <property name="url"> 
      <value>jdbc:mysql://localhost:3306/springdb</value> 
    </property> 
    <property name="username"> 
      <value>root</value> 
    </property> 
    <property name="password"> 
      <value>leizhimin</value> 
    </property> 
  </bean> 

  <bean id="basedao" class="com.lavasoft.springnote.ch05_jdbc03_temp.basedao" abstract="true">
    <property name="datasource"> 
      <ref bean="datasource"/> 
    </property> 
  </bean> 

  <bean id="userdao" 
     class="com.lavasoft.springnote.ch05_jdbc03_temp.userdao" parent="basedao"> 
  </bean> 

</beans>

 

import org.springframework.context.applicationcontext; 
import org.springframework.context.support.filesystemxmlapplicationcontext; 

/** 
* created by intellij idea.<br> 
* <b>user</b>: leizhimin<br> 
* <b>date</b>: 2008-4-22 15:59:18<br> 
* <b>note</b>: 测试类，客户端 
*/ 
public class springdaodemo { 
  public static void main(string[] args) { 
    applicationcontext context = new filesystemxmlapplicationcontext("d:\\_spring\\src\\com\\lavasoft\\springnote\\ch05_jdbc03_temp\\bean-jdbc-temp.xml"); 
    user user = new user(); 
    user.setname("hahhahah"); 
    user.setage(new integer(22)); 
    iuserdao userdao = (iuserdao) context.getbean("userdao"); 
    userdao.insert(user); 
    user = userdao.find(new integer(1)); 
    system.out.println("name: " + user.getname()); 
  } 
}

 
运行结果：

log4j:warn no appenders could be found for logger (org.springframework.core.collectionfactory). 
log4j:warn please initialize the log4j system properly. 
name: jdbctemplate 

process finished with exit code 0

spring dao之hibernate
 
hibernatedaosupport - hibernate数据访问对象的基类。 需要一个sessionfactory，同时为子类提供 hibernatetemplate。也可以选择直接通过 提供一个hibernatetemplate来初始化， 这样就可以重用后者的设置，例如sessionfactory， flush模式，异常翻译器（exception translator）等等。

本节主要讨论sping对hibernatetemplate的支持。

下面是个例子：
 

drop table if exists user; 

/*==============================================================*/ 
/* table: user                         */ 
/*==============================================================*/ 
create table user 
( 
  id          bigint auto_increment not null, 
  name         varchar(24), 
  age         int, 
  primary key (id) 
); 

 

/** 
* created by intellij idea.<br> 
* <b>note</b>: hiberante实体类 
*/ 
public class user { 
  private integer id; 
  private string name; 
  private integer age; 

  public integer getid() { 
    return id; 
  } 

  public void setid(integer id) { 
    this.id = id; 
  } 

  public string getname() { 
    return name; 
  } 

  public void setname(string name) { 
    this.name = name; 
  } 

  public integer getage() { 
    return age; 
  } 

  public void setage(integer age) { 
    this.age = age; 
  } 
}

 

<?xml version="1.0" encoding="utf-8"?> 
<!doctype hibernate-mapping 
  public "-//hibernate/hibernate mapping dtd 3.0//en" 
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping> 

  <class name="com.lavasoft.springnote.ch06_hbm_02detx.user" 
      table="user"> 

    <id name="id" column="id"> 
      <generator class="native"/> 
    </id> 

    <property name="name" column="name"/> 

    <property name="age" column="age"/> 

  </class> 

</hibernate-mapping>

 

/** 
* created by intellij idea.<br> 
* <b>user</b>: leizhimin<br> 
* <b>date</b>: 2008-4-23 15:37:43<br> 
* <b>note</b>: dao接口 
*/ 
public interface iuserdao { 
  public void insert(user user); 
  public user find(integer id); 
} 
 
import org.hibernate.sessionfactory; 
import org.springframework.orm.hibernate3.hibernatetemplate; 

/** 
* created by intellij idea.<br> 
* <b>user</b>: leizhimin<br> 
* <b>date</b>: 2008-4-23 15:15:55<br> 
* <b>note</b>: dao实现 
*/ 
public class userdao implements iuserdao { 
  private hibernatetemplate hibernatetemplate; 

  public void setsessionfactory(sessionfactory sessionfactory) { 
    this.hibernatetemplate =new hibernatetemplate(sessionfactory); 
  } 

  public void insert(user user) { 
    hibernatetemplate.save(user); 
    system.out.println("所保存的user对象的id:"+user.getid()); 
  } 

  public user find(integer id) { 
    user user =(user) hibernatetemplate.get(user.class, id); 
    return user; 
  } 
}

 

<?xml version="1.0" encoding="utf-8"?> 
<!doctype beans public "-//spring/dtd bean/en" 
"http://www.springframework.org/dtd/spring-beans.dtd"> 
<beans> 
  <bean id="datasource" 
     class="org.springframework.jdbc.datasource.drivermanagerdatasource"> 
    <property name="driverclassname"> 
      <value>com.mysql.jdbc.driver</value> 
    </property> 
    <property name="url"> 
      <value>jdbc:mysql://localhost:3306/springdb</value> 
    </property> 
    <property name="username"> 
      <value>root</value> 
    </property> 
    <property name="password"> 
      <value>leizhimin</value> 
    </property> 
  </bean> 

  <bean id="sessionfactory" 
     class="org.springframework.orm.hibernate3.localsessionfactorybean" 
     destroy-method="close"> 
    <property name="datasource"> 
      <ref bean="datasource"/> 
    </property> 
    <property name="mappingresources"> 
      <list> 
        <value>com/lavasoft/springnote/ch06_hbm_02protx/user.hbm.xml</value> 
      </list> 
    </property> 
    <property name="hibernateproperties"> 
      <props> 
        <prop key="hibernate.dialect"> 
          org.hibernate.dialect.mysqldialect 
        </prop> 
      </props> 
    </property> 
  </bean> 


  <bean id="userdao" class="com.lavasoft.springnote.ch06_hbm_02protx.userdao"> 
    <property name="sessionfactory"> 
      <ref bean="sessionfactory"/> 
    </property> 
  </bean> 
</beans>

 

import org.springframework.context.applicationcontext; 
import org.springframework.context.support.filesystemxmlapplicationcontext; 

/** 
* created by intellij idea.<br> 
* <b>note</b>: 测试类、客户端 
*/ 
public class springhibernatedemo { 
  public static void main(string[] args) { 
    applicationcontext context =new filesystemxmlapplicationcontext("d:\\_spring\\src\\com\\lavasoft\\springnote\\ch06_hbm_02protx\\bean-hbm_tx.xml"); 

    // 建立dao物件 
    iuserdao userdao = (iuserdao) context.getbean("userdao"); 

    user user = new user(); 
    user.setname("caterpillar"); 
    user.setage(new integer(30)); 

    userdao.insert(user); 

    user = userdao.find(new integer(1)); 

    system.out.println("name: " + user.getname()); 
  } 
}

 
运行结果：

log4j:warn no appenders could be found for logger (org.springframework.core.collectionfactory). 
log4j:warn please initialize the log4j system properly. 
所保存的user对象的id:18 
name: jdbctemplate 

process finished with exit code 0