JDBC事务难题

Question

大牛们 ，，，有一段加了JDBC事务的方法
[code="java"]
public boolean updateStuAcc(int stuID, List accL, int schID) {
boolean b = true;
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
String sql1 = "select * from stuAccounts where stuID!=? and Account=?";
String sql2 = "update stuAccounts set Account=? where pactID=?";
String sql3 = "update [" + schID
+ "_StuRefundInfo] set account=? where pactID=? ";
try {
conn = DBCon.getCon();
conn.setAutoCommit(false);
for (int i = 0; i < accL.size(); i++) {
StuUpdateAccDto suaDto = (StuUpdateAccDto) accL.get(i);
ps = conn.prepareStatement(sql1);
ps.setInt(1, stuID);
ps.setString(2, suaDto.getAccount());
rs = ps.executeQuery();
if (rs.next()) {
b = false;
break;
} else {
ps = conn.prepareStatement(sql2);
ps.setString(1, suaDto.getAccount());
ps.setString(2, suaDto.getPactID());
ps.executeUpdate();
ps = conn.prepareStatement(sql3);
ps.setString(1, suaDto.getAccount());
ps.setString(2, suaDto.getPactID());
ps.execute();
}
}
conn.commit();
} catch (SQLException e) {
b = false;
try {
conn.rollback();
} catch (SQLException e1) {
e1.printStackTrace();
}
e.printStackTrace();
} finally {
try {
if (rs != null) {
rs.close();
}
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
return b;
}
[/code]

该方法有时候会抛出这样的异常

at java.lang.Thread.run(Thread.java:595)
com.microsoft.sqlserver.jdbc.SQLServerException: 事务(进程 ID 54)与另一个进程被
死锁在 锁 资源上，并且已被选作死锁牺牲品。请重新运行该事务。
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError
(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(Unknown
Source)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePrep
aredStatement(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecC
md.doExecute(Unknown Source)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(Unkno
wn Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(Unknow
n Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(Unkn
own Source)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.executeQuery(
Unknown Source)
at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeQuery(
DelegatingPreparedStatement.java:93)
at dao.StuAllInfoUDao.updateStuAcc(StuAllInfoUDao.java:33)
at workerServlet.SchUpdateStuInfoServlet.doPost(SchUpdateStuInfoServlet.
java:59)

请问是什么原因？？？？

Answer 1

[code="java"]
try {

conn = DBCon.getCon();

conn.setAutoCommit(false);

for (int i = 0; i < accL.size(); i++) {

StuUpdateAccDto suaDto = (StuUpdateAccDto) accL.get(i);

ps = conn.prepareStatement(sql1);

ps.setInt(1, stuID);

ps.setString(2, suaDto.getAccount());

rs = ps.executeQuery();

if (rs.next()) {

b = false;

break;

} else {
if (ps != null) {

ps.close();

}
ps = conn.prepareStatement(sql2);

ps.setString(1, suaDto.getAccount());

ps.setString(2, suaDto.getPactID());

ps.executeUpdate();
if (ps != null) {

ps.close();

}
ps = conn.prepareStatement(sql3);

ps.setString(1, suaDto.getAccount());

ps.setString(2, suaDto.getPactID());

ps.execute();

}

}

conn.commit();

}
[/code]