spring3之JdbcTemplate详解
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./schema/beans" xmlns:xsi="http://www./2001/XMLSchema-instance" xmlns:context="http://www./schema/context" xmlns:aop="http://www./schema/aop" xmlns:tx="http://www./schema/tx" xsi:schemaLocation="http://www./schema/beans http://www./schema/beans/spring-beans-2.5.xsd http://www./schema/context http://www./schema/context/spring-context-2.5.xsd http://www./schema/aop http://www./schema/aop/spring-aop-2.5.xsd http://www./schema/tx http://www./schema/tx/spring-tx-2.5.xsd"> <context:property-placeholder location="classpath:jdbc.properties"/> <!-- dataSource可以为c3p0、proxool等 -->
<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> <!--Caused by: java.lang.NoClassDefFoundError: org/aopalliance/intercept/MethodInterceptor aop错误引入spring.jar
-->
<aop:config> <!--
1)execution(* *(..))
表示匹配所有方法 2)execution(public * com. savage.service.UserService.*(..)) 表示匹配com.savage.server.UserService中所有的公有方法 3)execution(* com.savage.server..*.*(..)) 表示匹配com.savage.server包及其子包下的所有方法 --> <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}); } @Transactional(rollbackFor = Exception.class)
//出现异常Exception时回滚该方法事务
public void insertUser() throws Exception {
jdbcTemplate.update("insert into user (name) values ('01');");
jdbcTemplate.update("update user set name=a where id=0;");
} }【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。
后台抛出异常,查看数据库,记录插入进去了,说明我们配置事务不对RuntimeException回滚生效了. |
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来自: 用勿龍潛 > 《spring jdbcTemplate》