缺点:Service层面还是不应该出现关于事务的操作
1.自行创建C3P0Uti,account数据库,导入Jar包
2.Dao层面
接口:
package com.learning.dao; import com.learning.domain.Account; public interface AccountDao { /** * 转账 * @param fromname 转出用户 * @param toname 转入用户 * @param money 转账金额 */ @Deprecated public void updateAccount(String fromname,String toname,double money)throws Exception; /** * 根据账户信息修改金额 * @param accout */ public void updateAccout(Account accout) throws Exception; /** * 根据用户名查找账户信息 * @param name * @return * @throws Exception */ public Account findAccountByName(String name)throws Exception; }
实现类:
package com.learning.dao.impl; import java.sql.Connection; import java.sql.SQLException; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanHandler; import com.learning.dao.AccountDao; import com.learning.domain.Account; import com.learning.util.C3P0Util; public class AccountDaoImpl implements AccountDao { private Connection conn; public AccountDaoImpl(Connection conn) { this.conn = conn; } public void updateAccount(String fromname, String toname, double money) throws Exception { //创建一个QueryRunner对象 QueryRunner qr = new QueryRunner(C3P0Util.getDataSource()); qr.update("update account set money=money-? where name=?",money,fromname); qr.update("update account set money=money+? where name=?",money,toname); } public void updateAccout(Account account) throws Exception { QueryRunner qr = new QueryRunner(); qr.update(conn,"update account set money=? where name=?",account.getMoney(),account.getName()); } public Account findAccountByName(String name) throws Exception { QueryRunner qr = new QueryRunner(); return qr.query(conn,"select * from account where name=?", new BeanHandler<Account>(Account.class),name); } }
3.Service层面
接口:
package com.learning.service; public interface AccountService { /** * 转账 * @param fromname 转出用户 * @param toname 转入用户 * @param money 转账金额 */ public void transfer(String fromname,String toname,double money); }
实现类:
package com.learning.service.impl; import java.sql.Connection; import java.sql.SQLException; import com.learning.dao.AccountDao; import com.learning.dao.impl.AccountDaoImpl; import com.learning.domain.Account; import com.learning.service.AccountService; import com.learning.util.C3P0Util; import com.learning.util.ManagerThreadLocal; public class AccountServiceImpl implements AccountService { public void transfer(String fromname, String toname, double money) { // ad.updateAccount(fromname, toname, money); AccountDao ad = new AccountDaoImpl(); try { ManagerThreadLocal.startTransacation();//begin //分别得到转出和转入账户对象 Account fromAccount = ad.findAccountByName(fromname); Account toAccount = ad.findAccountByName(toname); //修改账户各自的金额 fromAccount.setMoney(fromAccount.getMoney()-money); toAccount.setMoney(toAccount.getMoney()+money); //完成转账操作 ad.updateAccout(fromAccount); // int i = 10/0; ad.updateAccout(toAccount); ManagerThreadLocal.commit();//提交事务 } catch (Exception e) { try { ManagerThreadLocal.rollback();//回滚事务 } catch (Exception e1) { e1.printStackTrace(); } }finally{ try { ManagerThreadLocal.close(); } catch (Exception e) { e.printStackTrace(); }//关闭 } } }
4.创建ManagerThreadLocal管理Connection
package com.learning.util; import java.sql.Connection; import java.sql.SQLException; public class ManagerThreadLocal { private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>(); //得到一个连接 public static Connection getConnection(){ Connection conn = tl.get();//从当前线程中取出一个连接 if(conn==null){ conn = C3P0Util.getConnection();//从池中取出一个 tl.set(conn);//把conn对象放入到当前线程对象中 } return conn; } //开始事务 public static void startTransacation(){ try { Connection conn = getConnection(); conn.setAutoCommit(false);//从当前线程对象中取出的连接,并开始事务 } catch (SQLException e) { e.printStackTrace(); } } public static void commit(){ try { getConnection().commit();//提交事务 } catch (SQLException e) { e.printStackTrace(); } } public static void rollback(){ try { getConnection().rollback();//回滚事务 } catch (SQLException e) { e.printStackTrace(); } } public static void close(){ try { getConnection().close();//把连接放回池中 tl.remove();//把当前线程对象中的conn移除 } catch (SQLException e) { e.printStackTrace(); } } }
时间: 2024-11-06 10:36:03