JdbcTemplate详解1

1、JdbcTemplate操作数据库

Spring对数据库的操作在jdbc上面做了深层次的封装，使用spring的注入功能，可以把DataSource注册到JdbcTemplate之中。同时，为了支持对properties文件的支持，spring提供了类似于EL表达式的方式，把dataSource.properties的文件参数引入到参数配置之中，<context:property-placeholder location="classpath:jdbc.properties" />。

 

实例代码如下：

提供数据源的相关配置信息：jdbc.properties

driverClassName=org.gjt.mm.mysql.Driver
url=jdbc\:mysql\://localhost\:3306/stanley?useUnicode\=true&characterEncoding\=UTF-8
username=root
password=123456
initialSize=1
maxActive=500
maxIdle=2
minIdle=1

提供spring的配置文件，将jdbc.properties与JdbcTemplate粘合起来的配置文件：beans.xml

<? xml version ="1.0" encoding ="UTF-8" ?>
< beans xmlns ="http://www.springframework.org/schema/beans"
             xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance"
             xmlns:context ="http://www.springframework.org/schema/context"
             xmlns:aop ="http://www.springframework.org/schema/aop"
             xmlns:tx ="http://www.springframework.org/schema/tx"
             xsi:schemaLocation="http://www.springframework.org/schema/beans
                     http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                     http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
                     http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
                     http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd" >

     < context:property-placeholder location ="classpath:jdbc.properties" />
     < bean id ="dataSource" class ="org.apache.commons.dbcp.BasicDataSource" destroy-method ="close" >
         < property name ="driverClassName" value ="${driverClassName}" />
         < property name ="url" value ="${url}" />
         < property name ="username" value ="${username}" />
         < property name ="password" value ="${password}" />
            <!-- 连接池启动时的初始值 -->
     < property name ="initialSize" value ="${initialSize}" />
     <!-- 连接池的最大值 -->
     < property name ="maxActive" value ="${maxActive}" />
     <!-- 最大空闲值.当经过一个高峰时间后，连接池可以慢慢将已经用不到的连接慢慢释放一部分，一直减少到maxIdle为止 -->
     < property name ="maxIdle" value ="${maxIdle}" />
     <!--     最小空闲值.当空闲的连接数少于阀值时，连接池就会预申请去一些连接，以免洪峰来时来不及申请 -->
     < property name ="minIdle" value ="${minIdle}" />
     </ bean >

   < bean id ="txManager" class ="org.springframework.jdbc.datasource.DataSourceTransactionManager" >
             < property name ="dataSource" ref ="dataSource" />
         </ bean >

   < aop:config >
         < aop:pointcut id ="transactionPointcut" expression ="execution(* cn.comp.service..*.*(..))" />
         < aop:advisor advice-ref ="txAdvice" pointcut-ref ="transactionPointcut" />
   </ aop:config >
   < tx:advice id ="txAdvice" transaction-manager ="txManager" >
         < tx:attributes >
             < tx:method name ="get*" read-only ="true" propagation ="NOT_SUPPORTED" />
             < tx:method name ="*" />
         </ tx:attributes >
   </ tx:advice >

   < bean id ="personService" class ="cn.comp.service.impl.PersonServiceBean" >
     < property name ="dataSource" ref ="dataSource" />
   </ bean >
</ beans >

 

或者使用获取jdbc相关连接

< bean name ="dataSource" class ="org.springframework.jdbc.datasource.DriverManagerDataSource" >
     < property name ="driverClassName" value ="com.mysql.jdbc.Driver" > </ property >
     < property name ="url" value ="jdbc:mysql://localhost/dbunit" > </ property >
     < property name ="password" value ="root" />
     < property name ="username" value ="root" />
   </ bean >

 

提供POJO的java类：Person.java

public class Person {
   private Integer id;
   private String name;
  
   public Person(){}
  
   public Person(String name) {
     this.name = name;
  }
   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;
  }
}

提供对Person的操作接口： PersonService.java

public interface PersonService {
   /**
    * 保存person
    * @param person
    */
   public void save(Person person);
   /**
    * 更新person
    * @param person
    */
   public void update(Person person);
   /**
    * 获取person
    * @param personid
    * @return
    */
   public Person getPerson(Integer personid);
   /**
    * 获取所有person
    * @return
    */
   public List<Person> getPersons();
   /**
    * 删除指定id的person
    * @param personid
    */
   public void delete(Integer personid) throws Exception;
}

提供对接口的实现类： PersonServiceBean.java

public class PersonServiceBean implements PersonService {
   private JdbcTemplate jdbcTemplate;
  
   public void setDataSource(DataSource dataSource) {
     this.jdbcTemplate = new JdbcTemplate(dataSource);
  }
  
   public void delete(Integer personid) throws Exception{
    jdbcTemplate.update( "delete from person where id=?", new Object[]{personid},
         new int[]{java.sql.Types.INTEGER});
  }
  
   public Person getPerson(Integer personid) {    
     return (Person)jdbcTemplate.queryForObject( "select * from person where id=?", new Object[]{personid},
         new int[]{java.sql.Types.INTEGER}, new PersonRowMapper());
  }

  @SuppressWarnings( "unchecked")
   public List<Person> getPersons() {
     return (List<Person>)jdbcTemplate.query( "select * from person", new PersonRowMapper());
  }

   public void save(Person person) {
    jdbcTemplate.update( "insert into person(name) values(?)", new Object[]{person.getName()},
         new int[]{java.sql.Types.VARCHAR});
  }

   public void update(Person person) {
    jdbcTemplate.update( "update person set name=? where id=?", new Object[]{person.getName(), person.getId()},
         new int[]{java.sql.Types.VARCHAR, java.sql.Types.INTEGER});
  }
}

提供在查询对象时，记录的映射回调类： PersonRowMapper.java

public class PersonRowMapper implements RowMapper {

   public Object mapRow(ResultSet rs, int index) throws SQLException {
    Person person = new Person(rs.getString( "name"));
    person.setId(rs.getInt( "id"));
     return person;
  }
}

【注意】：由于dbcp的jar包对common-pool和commons-collections的jar包有依赖，所有需要把他们一起引入到工程中。【  commons-dbcp-1.2.1.jar, commons-pool-1.2.jar, commons-collections-3.1.jar】, 参考文档《JDBC高级部分》：http://tianya23.blog.51cto.com/1081650/270849

 

2、JdbcTemplate事务

事务的操作首先要通过配置文件，取得spring的支持， 再在java程序中显示的使用@Transactional注解来使用事务操作。

 

在xml配置文件中增加对事务的支持：

< bean id ="txManager" class ="org.springframework.jdbc.datasource.DataSourceTransactionManager" >
             < property name ="dataSource" ref ="dataSource" />
         </ bean >
   < tx:annotation-driven transaction-manager ="txManager" />
  
   < bean id ="personService" class ="cn.comp.service.impl.PersonServiceBean" >
     < property name ="dataSource" ref ="dataSource" />
   </ bean >

在java程序中显示的指明是否需要事务，当出现运行期异常Exception或一般的异常Exception是否需要回滚

@Transactional
public class PersonServiceBean implements PersonService {
   private JdbcTemplate jdbcTemplate;
  
   public void setDataSource(DataSource dataSource) {
     this.jdbcTemplate = new JdbcTemplate(dataSource);
  }
   // unchecked ,
   // checked
  @Transactional(noRollbackFor=RuntimeException. class)
   public void delete(Integer personid) throws Exception{
    jdbcTemplate.update( "delete from person where id=?", new Object[]{personid},
         new int[]{java.sql.Types.INTEGER});
     throw new RuntimeException( "运行期例外");
  }
  @Transactional(propagation=Propagation.NOT_SUPPORTED)
   public Person getPerson(Integer personid) {    
     return (Person)jdbcTemplate.queryForObject( "select * from person where id=?", new Object[]{personid},
         new int[]{java.sql.Types.INTEGER}, new PersonRowMapper());
  }

  @Transactional(propagation=Propagation.NOT_SUPPORTED)
  @SuppressWarnings( "unchecked")
   public List<Person> getPersons() {
     return (List<Person>)jdbcTemplate.query( "select * from person", new PersonRowMapper());
  }

   public void save(Person person) {
    jdbcTemplate.update( "insert into person(name) values(?)", new Object[]{person.getName()},
         new int[]{java.sql.Types.VARCHAR});
  }

   public void update(Person person) {
    jdbcTemplate.update( "update person set name=? where id=?", new Object[]{person.getName(), person.getId()},
         new int[]{java.sql.Types.VARCHAR, java.sql.Types.INTEGER});
  }
}

在默认情况下，Spring会 对RuntimeException异常进行回滚操作，而对 Exception异常不进行回滚。可以显示的什么什么样的异常需要回滚，什么样的异常不需要回滚， 通过  @Transactional(noRollbackFor=RuntimeException.class)设置要求运行时异常不回滚 或者通过RollbackFor=Exception.class来要求需要捕获的异常回滚。

 

【注意】Spring对数据库的操作提供了强大的功能，比如 RowMapper接口封装数据库字段与Java属性的映射、查询返回List的函数等，但是里面还要写一堆SQL语句还是比较烦人的，在这部分建议使用ibatis或hibernate来代替， 不知道Spring后期的版本会不会把这个整合到里面。

 

< dependency >
       < groupId >com.alibaba.external </ groupId >
       < artifactId >sourceforge.spring </ artifactId >
       < version >2.5.6 </ version >
     </ dependency >
     < dependency >
       < groupId >com.alibaba.external </ groupId >
       < artifactId >jdbc.mysql.mysql-connector </ artifactId >
       < version >5.1.6 </ version >
     </ dependency >
     < dependency >
       < groupId >com.alibaba.external </ groupId >
       < artifactId >jakarta.commons.dbcp </ artifactId >
       < version >1.4 </ version >
     </ dependency >

 

 

转自：http://tianya23.blog.51cto.com/1081650/275292