spring_three

2020-12-13 04:42

阅读：437

标签：配置 localhost oid tsp new important ant tco nsf

转账案例

坐标:



 
 org.springframework
 spring-context
 5.0.2.RELEASE
 
 
 org.springframework
 spring-test
 5.0.2.RELEASE
 
 
 commons-dbutils
 commons-dbutils
 1.4
 

 
 mysql
 mysql-connector-java
 5.1.6
 

 
 c3p0
 c3p0
 0.9.1.2
 

 
 junit
 junit
 4.12

创建实体类daomain


/**
* 账户的实体类
*/
public class Account implements Serializable {
 private Integer id;
 private String name;
 private Float money;
}

创建接口AccountDao.java


/**
* 账户的持久层接口
*/
public interface AccountDao {

 /**
     * 查询所有
     * @return
     */
 ListAccount> findAllAccount();

 /**
     * 查询一个
     * @return
     */
 Account findAccountById(Integer accountId);

 /**
     * 保存
     * @param account
     */
 void saveAccount(Account account);

 /**
     * 更新
     * @param account
     */
 void updateAccount(Account account);

 /**
     * 删除
     * @param acccountId
     */
 void deleteAccount(Integer acccountId);

 /**
     * 根据名称查询账户
     * @param accountName
     * @return  如果有唯一的一个结果就返回，如果没有结果就返回null
     *          如果结果集超过一个就抛异常
     */
 Account findAccountByName(String accountName);
}

创建实现类AccountDaoImpl.java


/**
* 账户的持久层实现类
*/
public class AccountDaoImpl implements AccountDao {

 private QueryRunner runner;

 public ListAccount> findAllAccount() {
 try{
 return runner.query("select * from account",new BeanListHandlerAccount>(Account.class));
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public Account findAccountById(Integer accountId) {
 try{
 return runner.query("select * from account where id = ? ",new BeanHandlerAccount>(Account.class),accountId);
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public void saveAccount(Account account) {
 try{
            runner.update("insert into account(name,money)values(?,?)",account.getName(),account.getMoney());
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public void updateAccount(Account account) {
 try{
            runner.update("update account set name=?,money=? where id=?",account.getName(),account.getMoney(),account.getId());
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public void deleteAccount(Integer accountId) {
 try{
            runner.update("delete from account where id=?",accountId);
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public Account findAccountByName(String accountName) {
 try{
 ListAccount> accounts = runner.query("select * from account where name = ? ",new BeanListHandlerAccount>(Account.class),accountName);
 if(accounts == null || accounts.size() == 0){
 return null;
 }
 if(accounts.size() > 1){
 throw new RuntimeException("结果集不唯一，数据有问题");
 }
 return accounts.get(0);
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }
}

建接口AccountService.java


/**
* 账户的业务层接口
*/
public interface AccountService {

 /**
     * 查询所有
     * @return
     */
 ListAccount> findAllAccount();

 /**
     * 查询一个
     * @return
     */
 Account findAccountById(Integer accountId);

 /**
     * 保存
     * @param account
     */
 void saveAccount(Account account);

 /**
     * 更新
     * @param account
     */
 void updateAccount(Account account);

 /**
     * 删除
     * @param acccountId
     */
 void deleteAccount(Integer acccountId);

 /**
     * 转账
     * @param sourceName        转出账户名称
     * @param targetName        转入账户名称
     * @param money             转账金额
     */
 void transfer(String sourceName, String targetName, Float money);
}

创建接口的实现类，AccountServiceImpl.java


/**
* 账户的业务层实现类
*
* 事务控制应该都是在业务层
*/
public class AccountServiceImpl implements AccountService {

 private AccountDao accountDao;

 public void setAccountDao(AccountDao accountDao) {
 this.accountDao = accountDao;
 }


 public ListAccount> findAllAccount() {
 return accountDao.findAllAccount();
 }


 public Account findAccountById(Integer accountId) {
 return accountDao.findAccountById(accountId);

 }


 public void saveAccount(Account account) {
        accountDao.saveAccount(account);
 }


 public void updateAccount(Account account) {
        accountDao.updateAccount(account);
 }


 public void deleteAccount(Integer acccountId) {
        accountDao.deleteAccount(acccountId);
 }


 public void transfer(String sourceName, String targetName, Float money) {
 System.out.println("transfer....");
 //2.1根据名称查询转出账户
 Account source = accountDao.findAccountByName(sourceName);
 //2.2根据名称查询转入账户
 Account target = accountDao.findAccountByName(targetName);
 //2.3转出账户减钱
        source.setMoney(source.getMoney()-money);
 //2.4转入账户加钱
        target.setMoney(target.getMoney()+money);
 //2.5更新转出账户
        accountDao.updateAccount(source);

 int i=1/0;

 //2.6更新转入账户
        accountDao.updateAccount(target);
 }
}

配置applicationContext.xml


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

 
 id="accountService" class="com.it.service.impl.AccountServiceImpl">
 
 name="accountDao" ref="accountDao">
 

 
 id="accountDao" class="com.it.dao.impl.AccountDaoImpl">
 
 name="runner" ref="runner">
 

 
 id="runner" class="org.apache.commons.dbutils.QueryRunner" scope="prototype">
 name="ds" ref="dataSource">
 

 
 id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
 
 name="driverClass" value="com.mysql.jdbc.Driver">
 name="jdbcUrl" value="jdbc:mysql://localhost:3306/itcastspring">
 name="user" value="root">
 name="password" value="root">

测试AccountServiceTest.java


/**
* 使用Junit单元测试：测试我们的配置
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class AccountServiceTest {

 @Autowired
 private AccountService as;

 @Test
 public void testTransfer(){
        as.transfer("aaa","bbb",100f);
 }
}

事务被自动控制了。换言之，我们使用了connection对象的setAutoCommit(true)

添加事务

技术图片

如果在AccountServiceImpl.java中的transfer方法中，抛出一个异常。此时事务不会回滚，原因是DBUtils每个操作数据都是获取一个连接，每个连接的事务都是独立的，且默认是自动提交。

解决方案：

需要使用ThreadLocal对象把Connection和当前线程绑定，从而使一个线程中只能有一个能控制事务的连接对象。

ConnectionUtils.java


/**
* 连接的工具类，它用于从数据源中获取一个连接，并且实现和线程的绑定
*/
public class ConnectionUtils {

 private ThreadLocalConnection> tl = new ThreadLocalConnection>();
 //注入数据源
 private DataSource dataSource;

 public void setDataSource(DataSource dataSource) {
 this.dataSource = dataSource;
 }

 /**
     * 获取当前线程上的连接,
     * @return
     */
 public Connection getThreadConnection() {
 try{
 //1.先从ThreadLocal上获取
 Connection conn = tl.get();
 //2.判断当前线程上是否有连接
 if (conn == null) {
 //3.从数据源中获取一个连接，并且存入ThreadLocal中
                conn = dataSource.getConnection();
                tl.set(conn);
 }
 //4.返回当前线程上的连接
 return conn;
 }catch (Exception e){
 throw new RuntimeException(e);
 }
 }

 /**
     * 把连接和线程解绑（在当前线程结束的时候执行）
     */
 public void removeConnection(){
        tl.remove();
 }
}

TransactionManager.java

和事务管理相关的工具类，它包含了，开启事务，提交事务，回滚事务和释放连接


/**
* 和事务管理相关的工具类，它包含了，开启事务，提交事务，回滚事务和释放连接
*/
public class TransactionManager {

 private ConnectionUtils connectionUtils;

 public void setConnectionUtils(ConnectionUtils connectionUtils) {
 this.connectionUtils = connectionUtils;
 }

 /**
     * 开启事务
     */
 public void beginTransaction(){
 try {
            connectionUtils.getThreadConnection().setAutoCommit(false);
 }catch (Exception e){
            e.printStackTrace();
 }
 }

 /**
     * 提交事务
     */
 public void commit(){
 try {
            connectionUtils.getThreadConnection().commit();
 }catch (Exception e){
            e.printStackTrace();
 }
 }

 /**
     * 回滚事务
     */
 public void rollback(){
 try {
            connectionUtils.getThreadConnection().rollback();
 }catch (Exception e){
            e.printStackTrace();
 }
 }


 /**
     * 释放连接
     */
 public void release(){
 try {
            connectionUtils.getThreadConnection().close();//把连接还回连接池中
            connectionUtils.removeConnection();//线程和连接解绑
 }catch (Exception e){
            e.printStackTrace();
 }
 }
}

配置AccountDaoImpl.java

注入连接工具对象，使得操作数据库从同一个连接中获取


/**
* 账户的持久层实现类
*/
public class AccountDaoImpl implements AccountDao {

 private QueryRunner runner;
 private ConnectionUtils connectionUtils;

 public void setConnectionUtils(ConnectionUtils connectionUtils) {
 this.connectionUtils = connectionUtils;
 }

 public void setRunner(QueryRunner runner) {
 this.runner = runner;
 }

 public ListAccount> findAllAccount() {
 try{
 return runner.query(connectionUtils.getThreadConnection(),"select * from account",new BeanListHandlerAccount>(Account.class));
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public Account findAccountById(Integer accountId) {
 try{
 return runner.query(connectionUtils.getThreadConnection(),"select * from account where id = ? ",new BeanHandlerAccount>(Account.class),accountId);
 }catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public void saveAccount(Account account) {
 try{
            runner.update

上一篇：ubuntu上安装nodejs

下一篇：js地理定位对象 navigator.geolocation

文章来自：搜素材网的编程语言模块，转载请注明文章出处。
文章标题：spring_three
文章链接：http://soscw.com/index.php/essay/29765.html

亲，登录后才可以留言！

spring_three

转账案例

添加事务

评论

热门文章

推荐文章

最新文章

置顶文章