? 使用平臺： 1.??? Mysql 5.0.8 2.??? ibatis 2.3.4 3.??? spring 2.5 4.??? eclipse 3.3 完成賬戶的轉賬功能，在出現異常時回滾。由spring管理各個類之間的關系和事務處理。 - 首先建立兩個數據庫，一個在本機上，一個在遠端機上，腳本分別如下
?1 DROP?DATABASE?IF?EXISTS?testdb_a_zhanglong;
?2
?3CREATE?DATABASE?testdb_a_zhanglong;
?4
?5USE?testdb_a_zhanglong;
?6
?7CREATE?TABLE?Account(
?8????aid????????INT????????AUTO_INCREMENT,
?9????owner????????VARCHAR(20)????NOT?NULL,
10????balance????????Float(10,3)????DEFAULT?0.0,
11????PRIMARY?KEY(aid)
12);
13
14INSERT?INTO?Account?(owner,balance)?VALUES?('zhanglong',10000.00);
15 ?1DROP?DATABASE?IF?EXISTS?testdb_b_zhanglong;
?2
?3CREATE?DATABASE?testdb_b_zhanglong;
?4
?5USE?testdb_b_zhanglong;
?6
?7CREATE?TABLE?Account(
?8????aid????????INT????????AUTO_INCREMENT,
?9????owner????????VARCHAR(20)????NOT?NULL,
10????balance????????Float(10,3)????DEFAULT?0.0,
11????PRIMARY?KEY(aid)
12);
13
14INSERT?INTO?Account?(owner,balance)?VALUES?('zhengtao',10000.00);
15 在這里兩個數據庫是完全一樣的，是為了方便起見。 - 建立Account的JavaBean類
1package?com.aaron.atomikos.domain;
2
3  public?class?Account? {
4
5????private?int?accountId;
6????private?String?owner;
7????private?float?balance;
8 }
9 - 建立業務層接口AccountService
?1package?com.aaron.atomikos.service;
?2import?com.aaron.atomikos.domain.Account;
?3public?interface?AccountService?{
?4????void?addAccount(Account?account);
?5????
?6  ????/**?*//**
?7?????*?轉賬
?8?????*?@param?ida
?9?????*?@param?idb
10?????*?@param?amount
11?????*?@return
12 ?????*/
13????boolean?transfer(int?ida,int?idb,float?amount);?
14????
15????Account?getAccountById(int?id);
16}
17 ?
- 建立業務層接口實現類AccountServiceImpl
?1package?com.aaron.atomikos.service.impl;
?2import?com.aaron.atomikos.dao.AccountDao;
?3import?com.aaron.atomikos.domain.Account;
?4import?com.aaron.atomikos.service.AccountService;
?5public?class?AccountServiceImpl?implements?AccountService?{
?6
?7????//?數據庫a的Dao類
?8????private?AccountDao?accountaDao;
?9????//?數據庫b的Dao類
10????private?AccountDao?accountbDao;
11????public?AccountDao?getAccountbDao()?{
12????????return?accountbDao;
13????}
14????public?void?setAccountbDao(AccountDao?accountbDao)?{
15????????this.accountbDao?=?accountbDao;
16????}
17????public?AccountDao?getAccountDao()?{
18????????return?accountaDao;
19????}
20????public?void?setAccountaDao(AccountDao?accountaDao)?{
21????????this.accountaDao?=?accountaDao;
22????}
23????@Override
24????public?void?addAccount(Account?account)?{
25????????accountaDao.insertAccount(account);
26????}
27
28????@Override
29????public?boolean?transfer(int?ida,?int?idb,?float?amount)?{
30????????boolean?isSuccess?=?false;
31
32????????Account?accounta?=?new?Account();
33????????Account?accountb?=?new?Account();
34
35????????//檢查賬戶是否存在
36????????if?(!accountaDao.isExists(ida)?||?!accountbDao.isExists(idb))?{
37????????????throw?new?RuntimeException("賬戶"?+?ida?+?"或"?+?idb?+?"不存在");
38????????}
39????????
40????????//得到賬戶余額
41????????float?balancea?=?accountaDao.getBalance(ida);
42????????float?balanceb?=?accountbDao.getBalance(idb);
43????????if?(balancea?<?amount)?{
44????????????throw?new?RuntimeException("賬戶"?+?ida?+?"的余額不足！");
45????????}
46????????
47????????//轉賬
48????????accounta.setAccountId(ida);
49????????accountb.setAccountId(idb);
50????????accounta.setBalance(balancea?-?amount);
51????????accountb.setBalance(balanceb?+?amount);
52
53????????accountaDao.updateAccount(accounta);
54
55????????//兩次更新之間如果跑出異常，則會回滾操作
56????????//?if(true){
57????????//?throw?new?RuntimeException();
58????????//?}
59
60????????accountbDao.updateAccount(accountb);
61????????isSuccess?=?true;
62????????return?isSuccess;
63????}
64
65????@Override
66????public?Account?getAccountById(int?id)?{
67????????return?accountaDao.selectAccountById(id);
68????}
69}
70
建立DAO層AccountDao，繼承自spring的SqlMapClientDaoSupport，這里為了簡單起見，沒有使用接口，直接寫了具體實現類
?1package?com.aaron.atomikos.dao;
?2
?3import?org.springframework.orm.ibatis.support.SqlMapClientDaoSupport;
?4
?5import?com.aaron.atomikos.domain.Account;
?6
?7public?class?AccountDao?extends?SqlMapClientDaoSupport?{
?8
?9????/**?*//**
10?????*?插入賬戶
11?????*?
12?????*?@param?account
13?????*/
14????public?void?insertAccount(Account?account)?{
15????????getSqlMapClientTemplate().insert("Account.insertAccount",?account);
16????}
17
18????/**?*//**
19?????*?根據id刪除賬戶
20?????*?
21?????*?@param?id
22?????*/
23????public?void?deleteAccountById(int?id)?{
24????????getSqlMapClientTemplate().delete("Account.deleteAccountById",?id);
25????}
26
27????/**?*//**
28?????*?更新賬戶余額
29?????*?
30?????*?@param?account
31?????*/
32????public?void?updateAccount(Account?account)?{
33????????getSqlMapClientTemplate().update("Account.updateBalance",?account);
34????}
35
36????/**?*//**
37?????*?根據id查找賬戶
38?????*?
39?????*?@param?id
40?????*?@return
41?????*/
42????public?Account?selectAccountById(int?id)?{
43????????return?(Account)?getSqlMapClientTemplate().queryForObject(
44????????????????"Account.selectAccountById",?id);
45????}
46
47????/**?*//**
48?????*?根據賬戶編號得到余額
49?????*?
50?????*?@param?idb
51?????*?@return
52?????*/
53????public?float?getBalance(int?idb)?{
54????????return?Float.parseFloat(getSqlMapClientTemplate().queryForObject(
55????????????????"Account.selectBalance",?idb).toString());
56????}
57
58????/**?*//**
59?????*?判斷賬戶是否存在
60?????*?
61?????*?@param?ida
62?????*?@return
63?????*/
64????public?boolean?isExists(int?ida)?{
65????????return?(Integer)?getSqlMapClientTemplate().queryForObject(
66????????????????"Account.selectCount",?ida)?>?0???true?:?false;
67????}
68} 編寫iBATIS的sql映射文件Account.xml
?1<?xml?version="1.0"?encoding="UTF-8"?>
?2<!DOCTYPE?sqlMap?PUBLIC?"-//ibatis.apache.org//DTD?SQL?Map?2.0//EN"?"http://ibatis.apache.org/dtd/sql-map-2.dtd"?>
?3<sqlMap?namespace="Account">
?4????<typeAlias?alias="Account"?type="com.aaron.atomikos.domain.Account"?/>
?5????<select?id="selectAccountById"?parameterClass="int"?resultClass="Account">
?6????????select?*?from?Account?where?aid?=?#value#
?7????</select>
?8????
?9????<select?id="selectBalance"?parameterClass="int"?resultClass="float">
10????????select?balance?from?Account?where?aid?=?#value#
11????</select>
12????
13????<select?id="selectCount"?parameterClass="int"?resultClass="int">
14????????select?count(*)?from?Account?where?aid?=?#value#
15????</select>
16????
17????<update?id="updateBalance"?parameterClass="Account">
18????????update?Account?set?balance?=?#balance#?where?aid?=?#accountId#
19????</update>
20????
21????<insert?id="insertAccount"?parameterClass="Account">
22????????insert?into?Account?(owner,balance)?values?(#owner#,#balance#);
23????</insert>
24</sqlMap> 還要建立兩個ibatis的配置文件sql-map-config_A.xml和sql-map-config_B.xml，由于有兩個數據庫，所以要建兩個。具體不列出。
編寫spring的applicationContext.xml
??1<?xml?version="1.0"?encoding="UTF-8"?>
??2<beans?xmlns="http://www.springframework.org/schema/beans"
??3????xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
??4????xmlns:jee="http://www.springframework.org/schema/jee"
??5????xmlns:aop="http://www.springframework.org/schema/aop"
??6????xmlns:tx="http://www.springframework.org/schema/tx"
??7????xsi:schemaLocation="http://www.springframework.org/schema/beans?http://www.springframework.org/schema/beans/spring-beans-2.0.xsd?
??8?????????????????????http://www.springframework.org/schema/jee?http://www.springframework.org/schema/jee/spring-jee-2.0.xsd?
??9?????????????????????http://www.springframework.org/schema/aop?http://www.springframework.org/schema/aop/spring-aop-2.0.xsd?
?10?????????????????????http://www.springframework.org/schema/tx?http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
?11
?12????<!--?讀取數據庫連接配置文件?-->
?13????<bean?id="propertyConfig"
?14????????class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
?15????????<property?name="locations">
?16????????????<list>
?17????????????????<value>classpath:jdbc.properties</value>
?18????????????</list>
?19????????</property>
?20????</bean>
?21
?22????<!--?數據源A(使用com.atomikos.jdbc.AtomikosDataSourceBean作為數據源)?-->
?23????<bean?id="datasourceA"
?24????????class="com.atomikos.jdbc.AtomikosDataSourceBean"?init-method="init"
?25????????destroy-method="close">
?26????????<property?name="uniqueResourceName">
?27????????????<value>mysql/db_a</value>
?28????????</property>
?29????????<property?name="xaDataSourceClassName">
?30????????????<value>${jdbc.driverClassName}</value>
?31????????</property>
?32????????<property?name="poolSize">
?33????????????<value>3</value>
?34????????</property>
?35?????????<property?name="xaProperties">
?36?????????????<props>
?37?????????????????<prop?key="url">${jdbc.url}</prop>
?38?????????????????<prop?key="user">${jdbc.username}</prop>
?39?????????????????<prop?key="password">${jdbc.password}</prop>
?40?????????????</props>
?41?????????</property>
?42????</bean>
?43
?44????<!--?數據源B（使用com.atomikos.jdbc.SimpleDataSourceBean作為數據源）?-->
?45????<bean?id="datasourceB"
?46????????class="com.atomikos.jdbc.SimpleDataSourceBean"?init-method="init"
?47????????destroy-method="close">
?48????????<property?name="uniqueResourceName">
?49????????????<value>mysql/db_b</value>
?50????????</property>
?51????????<property?name="xaDataSourceClassName">
?52????????????<value>${jdbc2.driverClassName}</value>
?53????????</property>
?54????????<property?name="xaDataSourceProperties">
?55????????????<value>user=${jdbc2.username};password=${jdbc2.password};url=${jdbc2.url};encoding=${jdbc2.encoding}</value>
?56????????</property>
?57????????<property?name="exclusiveConnectionMode">
?58????????????<value>true</value>
?59????????</property>
?60????????<property?name="validatingQuery">
?61????????????<value>SELECT?1</value>
?62????????</property>
?63????????<property?name="connectionPoolSize">
?64????????????<value>3</value>
?65????????</property>
?66????</bean>
?67
?68????<!--?配置atomikos的事務管理器?-->
?69????<bean?id="atomikosTransactionManager"
?70????????class="com.atomikos.icatch.jta.UserTransactionManager"
?71????????init-method="init"?destroy-method="close">
?72????????<property?name="forceShutdown"?value="true"?/>
?73????</bean>
?74
?75????<bean?id="atomikosUserTransaction"
?76????????class="com.atomikos.icatch.jta.UserTransactionImp">
?77????????<property?name="transactionTimeout"?value="300"?/>
?78????</bean>
?79
?80????<!--?spring的JTA事務管理器?-->
?81????<bean?id="springTransactionManager"
?82????????class="org.springframework.transaction.jta.JtaTransactionManager">
?83????????<property?name="transactionManager"
?84????????????ref="atomikosTransactionManager"?/>
?85????????<property?name="userTransaction"?ref="atomikosUserTransaction"?/>
?86????</bean>
?87
?88????<!--?通知配置?-->
?89????<tx:advice?id="txAdvice"
?90????????transaction-manager="springTransactionManager">
?91????????<tx:attributes>
?92????????????<tx:method?name="delete*"?rollback-for="Exception"?/>
?93????????????<tx:method?name="save*"?rollback-for="Exception"?/>
?94????????????<tx:method?name="update*"?rollback-for="Exception"?/>
?95????????????<tx:method?name="*"?read-only="true"
?96????????????????rollback-for="Exception"?/>
?97????????</tx:attributes>
?98????</tx:advice>
?99
100????<!--?事務切面配置?-->
101????<aop:config>
102????????<aop:pointcut?id="serviceOperation"
103????????????expression="execution(*?*..service*..*(..))"?/>
104????????<aop:advisor?advice-ref="txAdvice"
105????????????pointcut-ref="serviceOperation"?/>
106????</aop:config>
107
108????<!--?根據dataSourceA和sql-map-config_A.xml創建一個SqlMapClientA?-->
109????<bean?id="sqlMapClientA"
110????????class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
111????????<property?name="dataSource">
112????????????<ref?local="datasourceA"?/>
113????????</property>
114????????<property?name="configLocation">
115????????????<value>classpath:/sql-map-config_A.xml</value>
116????????</property>
117????</bean>
118
119????<!--?根據dataSourceB和sql-map-config_B.xml創建一個SqlMapClientB?-->
120????<bean?id="sqlMapClientB"
121????????class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
122????????<property?name="dataSource">
123????????????<ref?local="datasourceB"?/>
124????????</property>
125????????<property?name="configLocation">
126????????????<value>classpath:/sql-map-config_B.xml</value>
127????????</property>
128????</bean>
129
130????<!--根據sqlMapClientA創建一個SqlMapClientTemplate的模版類實例sqlMapClientTemplateA-->
131????<bean?id="sqlMapClientTemplateA"
132????????class="org.springframework.orm.ibatis.SqlMapClientTemplate">
133????????<property?name="sqlMapClient"?ref="sqlMapClientA"?/>
134????</bean>
135
136????<!--根據sqlMapClientB創建一個SqlMapClientTemplate的模版類實例sqlMapClientTemplateB-->
137????<bean?id="sqlMapClientTemplateB"
138????????class="org.springframework.orm.ibatis.SqlMapClientTemplate">
139????????<property?name="sqlMapClient"?ref="sqlMapClientB"?/>
140????</bean>
141
142????<!--?配置DAO?-->
143????<bean?id="accountaDao"?class="com.aaron.atomikos.dao.AccountDao">
144????????<property?name="sqlMapClientTemplate"
145????????????ref="sqlMapClientTemplateA"?/>
146????</bean>
147
148????<bean?id="accountbDao"?class="com.aaron.atomikos.dao.AccountDao">
149????????<property?name="sqlMapClientTemplate"
150????????????ref="sqlMapClientTemplateB"?/>
151????</bean>
152
153????<!--?配置service?-->
154????<bean?id="accountService"
155????????class="com.aaron.atomikos.service.impl.AccountServiceImpl">
156????????<property?name="accountaDao"?ref="accountaDao"?/>
157????????<property?name="accountbDao"?ref="accountbDao"?/>
158????</bean>
159</beans> 在這里，我使用了兩個不同類的數據源，只是為了測試，具體配置如上。兩者設置屬性時有點差別，數據源com.atomikos.jdbc.AtomikosDataSourceBean中設置url,user,password屬性是用xaProperties這個屬性，它是個Properties類型，所以要用<props>標簽分開設置，數據源com.atomikos.jdbc.SimpleDataSourceBean中設置url,user,password屬性使用xaDataSourceProperties這個屬性，它是String類型，查看源代碼可以知道，這個類會把xaDataSourceProperties按“;”進行分割，得到user=root,password=root等幾個字符串，再將“=”兩邊的字符串分別作為屬性名和屬性值放入一個properties變量中。有一點要注意，
1<value>user=${jdbc2.username};password=${jdbc2.password};url=${jdbc2.url};encoding=${jdbc2.encoding}</value> 中的<value>和user=${jdbc2.username}之間不能換行，因為該類不會忽略換行，會把換行加上user當成一個字符串，之后會報錯的。
編寫測試類AccountServiceTest
?1package?com.aaron.atomikos.test;
?2
?3import?org.springframework.context.ApplicationContext;
?4import?org.springframework.context.support.ClassPathXmlApplicationContext;
?5import?com.aaron.atomikos.service.AccountService;
?6import?junit.framework.Assert;
?7import?junit.framework.TestCase;
?8
?9public?class?AccountServiceTest?extends?TestCase?{
10
11????protected?static?ApplicationContext?????????????applicationContext;
12????protected?static?AccountService?accountService;
13????static?{
14????????applicationContext?=?new?ClassPathXmlApplicationContext("applicationContext.xml");
15????????accountService?=?(AccountService)?applicationContext.getBean("accountService");
16????}
17????
18????public?void?testTransfer(){
19????????int?ida?=?1;
20????????int?idb?=?1;
21????????Assert.assertNotNull(accountService.transfer(ida,?idb,?666));
22????}
23}
執行，查看數據庫，成功！若將AccountserviceImpl中的拋出異常注釋去掉，則會在兩個數據庫中回滾。
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