上一篇中：
Hibernate源代碼分析(一)：設計屬于我的SessionFactory和ConnectionProvider
分析到了SessionFactoryImpl.openSession()方法，該方法將其
職責委托給了SessionImpl，打開org.hibernate.impl.SessionImpl.java，看看實現代碼：
這段程序代碼里創建了一個新的對象connectionManager，我們跟蹤一下org.hibernate.jdbc.ConnectionManager.java，在這個文件里可以
發現一個方法openConnection()，代碼如下：
現在，最有價值的發現出來了，在第8行，這里就是從緩沖池獲得數據庫連接的代碼。
接下來我們可以設計實現ConnectionProvider的具體類了。
職責委托給了SessionImpl，打開org.hibernate.impl.SessionImpl.java，看看實現代碼：
1
SessionImpl(
2
final
Connectionconnection,
3
final
SessionFactoryImplfactory,
4
final
boolean
autoclose,
5
final
long
timestamp,
6
final
Interceptorinterceptor,
7
final
EntityModeentityMode,
8
final
boolean
flushBeforeCompletionEnabled,
9
final
boolean
autoCloseSessionEnabled,
10
final
ConnectionReleaseModeconnectionReleaseMode)
{
11
super
(factory);
12
this
.rootSession
=
null
;
13
this
.timestamp
=
timestamp;
14
this
.entityMode
=
entityMode;
15
this
.interceptor
=
interceptor;
16
this
.listeners
=
factory.getEventListeners();
17
this
.actionQueue
=
new
ActionQueue(
this
);
18
this
.persistenceContext
=
new
StatefulPersistenceContext(
this
);
19
this
.flushBeforeCompletionEnabled
=
flushBeforeCompletionEnabled;
20
this
.autoCloseSessionEnabled
=
autoCloseSessionEnabled;
21
this
.connectionReleaseMode
=
connectionReleaseMode;
22
this
.jdbcContext
=
new
JDBCContext(
this
,connection,interceptor);
23
24
if
(factory.getStatistics().isStatisticsEnabled())
{
25
factory.getStatisticsImplementor().openSession();
26
}
27
28
if
(log.isDebugEnabled())
{
29
log.debug(
"
openedsessionattimestamp:
"
+
timestamp);
30
}
31
}
SessionImpl(
2
final
Connectionconnection,
3
final
SessionFactoryImplfactory,
4
final
boolean
autoclose,
5
final
long
timestamp,
6
final
Interceptorinterceptor,
7
final
EntityModeentityMode,
8
final
boolean
flushBeforeCompletionEnabled,
9
final
boolean
autoCloseSessionEnabled,
10
final
ConnectionReleaseModeconnectionReleaseMode)
{
11
super
(factory);
12
this
.rootSession
=
null
;
13
this
.timestamp
=
timestamp;
14
this
.entityMode
=
entityMode;
15
this
.interceptor
=
interceptor;
16
this
.listeners
=
factory.getEventListeners();
17
this
.actionQueue
=
new
ActionQueue(
this
);
18
this
.persistenceContext
=
new
StatefulPersistenceContext(
this
);
19
this
.flushBeforeCompletionEnabled
=
flushBeforeCompletionEnabled;
20
this
.autoCloseSessionEnabled
=
autoCloseSessionEnabled;
21
this
.connectionReleaseMode
=
connectionReleaseMode;
22
this
.jdbcContext
=
new
JDBCContext(
this
,connection,interceptor);
23
24
if
(factory.getStatistics().isStatisticsEnabled())
{
25
factory.getStatisticsImplementor().openSession();
26
}
27
28
if
(log.isDebugEnabled())
{
29
log.debug(
"
openedsessionattimestamp:
"
+
timestamp);
30
}
31
}
我們關注的就是數據庫連接，重點關注第22行，在該行將Connection對象傳遞給了JDBCContext,通過觀察前 面的代碼我們可以發現，JTASessionContext.buildOrObtainSession() 方法傳遞的Connection對象為null，這個可以說，Connection對象的獲得將由
ConnectionProvider接口的實現類來完成。
接下來看看JDBCContent類的構造函數，跳轉到org.hibernate.jdbc.JDBCContent.java，程序代碼如下：
1
public
JDBCContext(Contextowner,Connectionconnection,Interceptorinterceptor)
{
2
this
.owner
=
owner;
3
this
.connectionManager
=
new
ConnectionManager(
4
owner.getFactory(),
5
this
,
6
owner.getConnectionReleaseMode(),
7
connection,
8
interceptor
9
);
10
11
final
boolean
registerSynchronization
=
owner.isAutoCloseSessionEnabled()
12
||
owner.isFlushBeforeCompletionEnabled()
13
||
owner.getConnectionReleaseMode()
==
ConnectionReleaseMode.AFTER_TRANSACTION;
14
if
(registerSynchronization)
{
15
registerSynchronizationIfPossible();
16
}
17
}
public
JDBCContext(Contextowner,Connectionconnection,Interceptorinterceptor)
{
2
this
.owner
=
owner;
3
this
.connectionManager
=
new
ConnectionManager(
4
owner.getFactory(),
5
this
,
6
owner.getConnectionReleaseMode(),
7
connection,
8
interceptor
9
);
10
11
final
boolean
registerSynchronization
=
owner.isAutoCloseSessionEnabled()
12
||
owner.isFlushBeforeCompletionEnabled()
13
||
owner.getConnectionReleaseMode()
==
ConnectionReleaseMode.AFTER_TRANSACTION;
14
if
(registerSynchronization)
{
15
registerSynchronizationIfPossible();
16
}
17
}
這段程序代碼里創建了一個新的對象connectionManager，我們跟蹤一下org.hibernate.jdbc.ConnectionManager.java，在這個文件里可以
發現一個方法openConnection()，代碼如下：
1
private
void
openConnection()
throws
HibernateException
{
2
if
(connection
!=
null
)
{
3
return
;
4
}
5
6
log.debug(
"
openingJDBCconnection
"
);
7
try
{
8
connection
=
factory.getConnectionProvider().getConnection();
9
}
10
catch
(SQLExceptionsqle)
{
11
throw
JDBCExceptionHelper.convert(
12
factory.getSQLExceptionConverter(),
13
sqle,
14
"
Cannotopenconnection
"
15
);
16
}
17
18
callback.connectionOpened();
//
registersynch;stats.connect()
19
}
private
void
openConnection()
throws
HibernateException
{
2
if
(connection
!=
null
)
{
3
return
;
4
}
5
6
log.debug(
"
openingJDBCconnection
"
);
7
try
{
8
connection
=
factory.getConnectionProvider().getConnection();
9
}
10
catch
(SQLExceptionsqle)
{
11
throw
JDBCExceptionHelper.convert(
12
factory.getSQLExceptionConverter(),
13
sqle,
14
"
Cannotopenconnection
"
15
);
16
}
17
18
callback.connectionOpened();
//
registersynch;stats.connect()
19
}
現在，最有價值的發現出來了，在第8行，這里就是從緩沖池獲得數據庫連接的代碼。
接下來我們可以設計實現ConnectionProvider的具體類了。
更多文章、技術交流、商務合作、聯系博主
微信掃碼或搜索：z360901061
微信掃一掃加我為好友
QQ號聯系： 360901061
您的支持是博主寫作最大的動力，如果您喜歡我的文章，感覺我的文章對您有幫助，請用微信掃描下面二維碼支持博主2元、5元、10元、20元等您想捐的金額吧，狠狠點擊下面給點支持吧，站長非常感激您！手機微信長按不能支付解決辦法：請將微信支付二維碼保存到相冊，切換到微信，然后點擊微信右上角掃一掃功能，選擇支付二維碼完成支付。
【本文對您有幫助就好】元
