Spring基础系列（三）

Bertha 。 2021-09-27 00:44 362阅读 0赞

# 一、JDBC模板对象 #

Spring整合了一个可以操作数据库的对象JDBCTemplate（JBDC模板对象），该对象封装了jdbc技术，与DBUtils中的QueryRunner非常相似。  
**演示一下JDBCTemplate的使用：**

//演示JDBC模板
    public class Demo { 
        @Test
        public void fun1() throws Exception {
            //0 准备连接池
            ComboPooledDataSource dataSource = new ComboPooledDataSource();
            dataSource.setDriverClass("com.mysql.jdbc.Driver");
            dataSource.setJdbcUrl("jdbc:mysql:///test");
            dataSource.setUser("root");
            dataSource.setPassword("666");
            //1 创建JDBC模板对象
            JdbcTemplate jt = new JdbcTemplate();
            jt.setDataSource(dataSource);
            //2 书写sql,并执行
            String sql = "insert into user values(null,'long') ";
            jt.update(sql);
        }
    }

运行结果：  
![这里写图片描述][70]  
**JDBCTemplate增删改查：  
UserDao ：**

public interface UserDao {
        //增
        void save(User u);
        //删
        void delete(Integer id);
        //改
        void update(User u);
        //查
        User getById(Integer id);
        //查
        int getTotalCount();
        //查
        List<User> getAll();
    }

**UserDaoImpl：**

//使用JDBC模板实现增删改查
    public class UserDaoImpl extends JdbcDaoSupport implements UserDao { 
        @Override
        public void save(User u) {
            String sql = "insert into t_user values(null,?) ";
            super.getJdbcTemplate().update(sql, u.getName());
        }
        @Override
        public void delete(Integer id) {
            String sql = "delete from t_user where id = ? ";
            super.getJdbcTemplate().update(sql,id);
        }
        @Override
        public void update(User u) {
            String sql = "update t_user set name = ? where id=? ";
            super.getJdbcTemplate().update(sql, u.getName(),u.getId());
        }
        @Override
        public User getById(Integer id) {
            String sql = "select * from t_user where id = ? ";
            return super.getJdbcTemplate().queryForObject(sql,new RowMapper<User>(){
                @Override
                public User mapRow(ResultSet rs, int arg1) throws SQLException {
                    User u = new User();
                    u.setId(rs.getInt("id"));
                    u.setName(rs.getString("name"));
                    return u;
                }}, id);
        }
        @Override
        public int getTotalCount() {
            String sql = "select count(*) from t_user ";
            Integer count = super.getJdbcTemplate().queryForObject(sql, Integer.class);
            return count;
        }
        @Override
        public List<User> getAll() {
            String sql = "select * from t_user ";
            List<User> list = super.getJdbcTemplate().query(sql, new RowMapper<User>(){
                @Override
                public User mapRow(ResultSet rs, int arg1) throws SQLException {
                    User u = new User();
                    u.setId(rs.getInt("id"));
                    u.setName(rs.getString("name"));
                    return u;
                }});
            return list;
        }
    }

**将其配置到Spring容器中：  
依赖关系：  
![这里写图片描述][70 1]  
配置文件如下：**

<?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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    
        
        <context:property-placeholder location="classpath:db.properties" />
    
        
        <bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
            <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
            <property name="driverClass" value="${jdbc.driverClass}" ></property>
            <property name="user" value="${jdbc.user}" ></property>
            <property name="password" value="${jdbc.password}" ></property>
        </bean>
    
        
        <bean name="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate" >
            <property name="dataSource" ref="dataSource" ></property>
        </bean>
    
        
        <bean name="userDao" class="jdbcTemplate.UserDaoImpl" >
            
            <property name="dataSource" ref="dataSource" ></property>
        </bean>
    
    </beans>

**测试：**

package jdbcTemplate;
    
    import com.mchange.v2.c3p0.ComboPooledDataSource;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.jdbc.core.JdbcTemplate;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
    
    import javax.annotation.Resource;
    
    /** * Created by KPL on 2018/7/1. */
    //演示JDBC模板
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration("classpath:spring-config.xml")
    public class Demo { 
        @Resource(name="userDao")
        private UserDao ud;
        @Test
        public void fun2() throws Exception{
            User u = new User();
            u.setName("naruto");
            ud.save(u);
        }
        @Test
        public void fun3() throws Exception{
            User u = new User();
            u.setId(2);
            u.setName("jack");
            ud.update(u);
    
        }
        @Test
        public void fun4() throws Exception{
            ud.delete(2);
        }
        @Test
        public void fun5() throws Exception{
            System.out.println(ud.getTotalCount());
        }
        @Test
        public void fun6() throws Exception{
            System.out.println(ud.getById(1));
        }
        @Test
        public void fun7() throws Exception{
            System.out.println(ud.getAll());
        }
    }

**运行结果：  
![这里写图片描述][70 2]  
public class UserDaoImpl extends JdbcDaoSupport继承了JdbcDaoSupport，Spring会根据连接池自动创建JDBC模板对象。也就是说不需要手动擦行间JBDC模板对象，从父类方法中直接获取即可。**

String sql = "insert into t_user values(null,?) "; super.getJdbcTemplate().update(sql, u.getName());

**此时，配置文件修改成如下：**

# 二、Spring事务管理 #

关于事务部分的基础，可以看这篇博客[JavaWeb基础系列（七）事务][JavaWeb]  
Spring封装了事务管理的代码：打开事务、提交事务、回滚事务。  
因为在不用平台，操纵事务的代码各不相同，于是Spring提供了一个接口PlatfromTransactionManager接口，针对不同的平台，提供不同的实现类。

***** 真正管理事务的对象
    org.springframework.jdbc.datasource.DataSourceTransactionManager 
    //使用 SpringJDBC 或 iBatis 进行持久化数据时使用
    org.springframework.orm.hibernate3.HibernateTransactionManager 
    //使用Hibernate 版本进行持久化数据时使用

事务的传播行为：决定业务方法之间调用，事务应该如何处理。

//保证同一个事务中
    PROPAGATION_REQUIRED 支持当前事务，如果不存在 就新建一个(默认)
    PROPAGATION_SUPPORTS 支持当前事务，如果不存在，就不使用事务
    PROPAGATION_MANDATORY 支持当前事务，如果不存在，抛出异常
    //保证没有在同一个事务中
    PROPAGATION_REQUIRES_NEW 如果有事务存在，挂起当前事务，创建一个新的事务
    PROPAGATION_NOT_SUPPORTED 以非事务方式运行，如果有事务存在，挂起当前事务
    PROPAGATION_NEVER 以非事务方式运行，如果有事务存在，抛出异常
    PROPAGATION_NESTED 如果当前事务存在，则嵌套事务执行

**演示一下Spring事务：  
先完成基本的转账功能：  
Dao：**

package Transaction.dao;
    
    public interface AccountDao {
        //加钱
        void increaseMoney(Integer id, Double money);
        //减钱
        void decreaseMoney(Integer id, Double money);
    }

**DaoImpl：**

public class AccountDaoImpl extends JdbcDaoSupport implements AccountDao { 
        @Override
        public void increaseMoney(Integer id, Double money) {
            getJdbcTemplate().update("update t_account set money = money+? where id = ? ", money,id);
        }
        @Override
        public void decreaseMoney(Integer id, Double money) {
            getJdbcTemplate().update("update t_account set money = money-? where id = ? ", money,id);
        }
    }

**XML文件：**

<?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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    
        
        <context:property-placeholder location="classpath:db.properties" />
    
        
        <bean name="dataSource1" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
            <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
            <property name="driverClass" value="${jdbc.driverClass}" ></property>
            <property name="user" value="${jdbc.user}" ></property>
            <property name="password" value="${jdbc.password}" ></property>
        </bean>
        
        <bean name="accountDao" class="Transaction.dao.AccountDaoImpl" >
            <property name="dataSource" ref="dataSource1" ></property>
        </bean>
        
        <bean name="accountService" class="Transaction.service.AccountServiceImpl" >
            <property name="ad" ref="accountDao" ></property>
        </bean>
    </beans>

**测试类：**

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration("classpath:spring-config2.xml")
    public class Demo { 
        @Resource(name="accountService")
        private AccountService as;
        @Test
        public void fun1(){
            as.transfer(1, 2, 100d);
        }
    }

**运行结果：  
![这里写图片描述][70 3]  
现在开始加事务：  
Spring管理事务的方式：  
编码式：（了解）  
将核心事务管理器配置到Spring容器：**

<?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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    
    
    <context:property-placeholder location="classpath:db.properties" />
    
    
    <bean name="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" >
        <property name="dataSource" ref="dataSource1" ></property>
    </bean>
    
    
    <bean name="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate" >
        <property name="transactionManager" ref="transactionManager" ></property>
    </bean>
    
    
    <bean name="dataSource1" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
        <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
        <property name="driverClass" value="${jdbc.driverClass}" ></property>
        <property name="user" value="${jdbc.user}" ></property>
        <property name="password" value="${jdbc.password}" ></property>
    </bean>
    
    <bean name="accountDao" class="Transaction.dao.AccountDaoImpl" >
        <property name="dataSource" ref="dataSource1" ></property>
    </bean>
    
    <bean name="accountService" class="Transaction.service.AccountServiceImpl" >
        <property name="ad" ref="accountDao" ></property>
        <property name="tt" ref="transactionTemplate" ></property>
    </bean>
    </beans>

ServiceImpl：

@Transactional(isolation=Isolation.REPEATABLE_READ,propagation=Propagation.REQUIRED,readOnly=true)
    public class AccountServiceImpl implements AccountService { 
        private AccountDao ad ;
        private TransactionTemplate tt;
        @Override
        public void transfer(final Integer from,final Integer to,final Double money) {
            tt.execute(new TransactionCallbackWithoutResult() {
                @Override
                protected void doInTransactionWithoutResult(TransactionStatus arg0) {
                    //减钱
                    ad.decreaseMoney(from, money);
                    int i = 1/0;
                    //加钱
                    ad.increaseMoney(to, money);
                }
            });
        }
    
        public void setAd(AccountDao ad) {
            this.ad = ad;
        }
    
        public void setTt(TransactionTemplate tt) {
            this.tt = tt;
        }
    }

测试代码：

运行结果，由于加入了事务，报错之后，钱并不会转过去：  
![这里写图片描述][70 4]  
**XML配置（aop）  
Spring内部已经封装了事务通知方法，那么咱们只需要将它配置到业务处理上去就可以了。**

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" 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-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd ">
    
        
        <context:property-placeholder location="classpath:db.properties" />
    
        
        <bean name="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" >
            <property name="dataSource" ref="dataSource" ></property>
        </bean>
        
        <bean name="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate" >
            <property name="transactionManager" ref="transactionManager" ></property>
        </bean>
    
        
        <tx:advice id="txAdvice" transaction-manager="transactionManager" >
            <tx:attributes>
                
                <tx:method name="save*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="persist*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="update*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="modify*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="delete*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="remove*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
                <tx:method name="get*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="true" />
                <tx:method name="find*" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="true" />
                <tx:method name="transfer" isolation="REPEATABLE_READ" propagation="REQUIRED" read-only="false" />
            </tx:attributes>
        </tx:advice>
    
        
        <aop:config >
            
            <aop:pointcut expression="execution(* Transaction.service.*ServiceImpl.*(..))" id="txPc"/>
            
            <aop:advisor advice-ref="txAdvice" pointcut-ref="txPc" />
        </aop:config>
    
        
        <bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
            <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
            <property name="driverClass" value="${jdbc.driverClass}" ></property>
            <property name="user" value="${jdbc.user}" ></property>
            <property name="password" value="${jdbc.password}" ></property>
        </bean>
    
        
        <bean name="accountDao" class="Transaction.dao.AccountDaoImpl" >
            <property name="dataSource" ref="dataSource" ></property>
        </bean>
        
        <bean name="accountService" class="Transaction.service.AccountServiceImpl" >
            <property name="ad" ref="accountDao" ></property>
            <property name="tt" ref="transactionTemplate" ></property>
        </bean>
    
    </beans>

**注解配置（aop）**

**加入注解：**

@Transactional(isolation= Isolation.REPEATABLE_READ,propagation= Propagation.REQUIRED,readOnly=true)
    public class AccountServiceImpl implements AccountService { 
        private AccountDao ad ;
        private TransactionTemplate tt;
    
        @Override
        @Transactional(isolation=Isolation.REPEATABLE_READ,propagation=Propagation.REQUIRED,readOnly=false)
        public void transfer(final Integer from,final Integer to,final Double money) {
            //减钱
            ad.decreaseMoney(from, money);
            int i = 1/0;
            //加钱
            ad.increaseMoney(to, money);
        }
        public void setAd(AccountDao ad) {
            this.ad = ad;
        }
    
        public void setTt(TransactionTemplate tt) {
            this.tt = tt;
        }
    }

**测试：**

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration("classpath:spring-config4.xml")
    public class Demo { 
        @Resource(name="accountService")
        private AccountService as;
        @Test
        public void fun1(){
            as.transfer(1, 2, 100d);
        }
    }

**运行结果，由于出错，钱不会转过去：  
![这里写图片描述][70 5]**

--------------------

**Spring系列目录：  
[Spring基础系列（一）][Spring]  
[Spring基础系列（二）][Spring 1]  
[Spring基础系列（三）][Spring 2]**

> **转载请标明出处，原文地址：[https://blog.csdn.net/weixin\_41835916][https_blog.csdn.net_weixin_41835916]  
> 如果觉得本文对您有帮助，请点击顶支持一下，您的支持是我写作最大的动力，谢谢。  
> ![这里写图片描述][70 6]**

[70]: /images/20210923/c4672488d7c8434c805f2125bb543d9a.png
[70 1]: /images/20210923/f2036316b1c148fcb51321c94df4fbaf.png
[70 2]: /images/20210923/f45402ada6f041f8b444820a732037d5.png
[JavaWeb]: https://blog.csdn.net/weixin_41835916/article/details/80788090
[70 3]: /images/20210923/04dd96625099478593135787ad16ab5b.png
[70 4]: /images/20210923/8df554c663db434dbb4e568dafc8fbfc.png
[70 5]: /images/20210923/47ea3d99bad348e983a53aa2a32b8e33.png
[Spring]: https://blog.csdn.net/weixin_41835916/article/details/80852760
[Spring 1]: https://blog.csdn.net/weixin_41835916/article/details/80872595
[Spring 2]: https://blog.csdn.net/weixin_41835916/article/details/80877562
[https_blog.csdn.net_weixin_41835916]: https://blog.csdn.net/weixin_41835916
[70 6]: /images/20210923/c9af864cb7294b2baf0eb3bc9743a732.png