JdbcTemplate与事务管理

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}" />

< property name ="initialSize" value ="${initialSize}" />

< property name ="maxActive" value ="${maxActive}" />

< property name ="maxIdle" value ="${maxIdle}" />

< 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 >

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 {

public void save(Person person);

public void update(Person person);

public Person getPerson(Integer personid);

public List<Person> getPersons();

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。

JdbcTemplate与事务管理

1、JdbcTemplate操作数据库

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