DBCP

c3p0

Druid

用戶名

username

user

username

密碼

password

password

password

URL

url

jdbcUrl

jdbcUrl

驅動類名

driverClassName

driverClass

driverClassName

DBCP

c3p0

Druid

最小連接數

minIdle(0)

minPoolSize(3)

minIdle(0)

初始化連接數

initialSize(0)

initialPoolSize(3)

initialSize(0)

最大連接數

maxTotal(8)

maxPoolSize(15)

maxActive(8)

最大等待時間

maxWaitMillis(毫秒)

maxIdleTime(0秒)

maxWait(毫秒)

DBCP

c3p0

Druid

開啟緩存功能

poolPreparedStatements

maxStatements

poolPreparedStatements

單個連接擁有的最大緩存數

maxOpenPrepared-

Statements

maxStatementsPer-

Connection

maxOpenPrepared-

Statements

DBCP

c3p0

Druid

申請連接檢測

testOnBorrow

testConnectionOnCheckin

testOnBorrow

是否超時檢測

testWhileIdle

testWhileIdle

空閑時間

timeBetweenEvictionRunsMillis

idleConnectionTestPeriod

timeBetweenEvictionRunsMillis

校驗用sql語句

validationQuery

preferredTestQuery

validationQuery

歸還連接檢測

testOnReturn

testConnectionOnCheckout

testOnReturn

DBCP

c3p0

Druid

是否超時關閉連接

removeAbandoned

breakAfterAcquireFailure

removeAbandoned

超時時間

removeAbandonedTimeout

checkoutTimeout

removeAbandonedTimeout

是否記錄日誌

logAbandoned

logAbandoned

DBCP

c3p0

Druid

重連次數

acquireRetryAttempts

間隔時間

acquireRetryDelay

屬性(Parameter)

默認值(Default)

描述(Description)

username

傳遞給JDBC驅動的用於建立連接的用戶名(The connection username to be passed to our JDBC driver to establish a connection.)

password

傳遞給JDBC驅動的用於建立連接的密碼(The connection password to be passed to our JDBC driver to establish a connection.)

url

傳遞給JDBC驅動的用於建立連接的URL(The connection URL to be passed to our JDBC driver to establish a connection.)

driverClassName

使用的JDBC驅動的完整有效的java 類名(The fully qualified Java class name of the JDBC driver to be used.)

defaultAutoCommit

driver default

連接池創建的連接的默認的auto-commit狀態,沒有設置則不會自動提交(The default auto-commit state of connections created by this pool. If not set then the setAutoCommit method will not be called.)

initialSize

0

初始化連接:連接池啟動時創建的初始化連接數量(The initial number of connections that are created when the pool is started.

maxTotal

8

最大活動連接:連接池在同一時間能夠分配的最大活動連接的數量, 如果設置為非正數則表示不限制(The maximum number of active connections that can be allocated from this pool at the same time, or negative for no limit.)

maxIdle

8

最大空閑連接:連接池中容許保持空閑狀態的最大連接數量,超過的空閑連接將被釋放,如果設置為負數表示不限制(The maximum number of connections that can remain idle in the pool, without extra ones being released, or negative for no limit.)

minIdle

0

最小空閑連接:連接池中容許保持空閑狀態的最小連接數量,負數表示沒有現在(The maximum number of connections that can remain idle in the pool, without extra ones being released, or negative for no limit.)

註意：如果在某些負載比較大的系統中將maxIdel設置過小時，很可能會出現連接關閉的同時新連接馬上打開的情況.這是由於關閉連接的線程比打開的快導致的.所以，對於這種系統中,maxIdle的設定值是不同的但是通常首選默認值

(NOTE: If maxIdle is set too low on heavily loaded systems it is possible you will see connections being closed and almost immediately new connections being opened. This is a result of the active threads momentarily closing connections faster than they are opening them, causing the number of idle connections to rise above maxIdle. The best value for maxIdle for heavily loaded system will vary but the default is a good starting point.)

maxWaitMillis

indefinitely

最大等待時間:當沒有可用連接時,連接池等待連接被歸還的最大時間(以毫秒計數),超過時間則拋出異常,如果設置為-1表示無限等待(The maximum number of milliseconds that the pool will wait (when there are no available connections) for a connection to be returned before throwing an exception, or -1 to wait indefinitely.)

validationQuery

SQL查詢,用來驗證從連接池取出的連接,在將連接返回給調用者之前.如果指定,則查詢必須是一個SQL SELECT並且必須返回至少一行記錄(The SQL query that will be used to validate connections from this pool before returning them to the caller. If specified, this query MUST be an SQL SELECT statement that returns at least one row. If not specified, connections will be validation by calling the isValid() method.)

testOnCreate

false

指明是否在建立連接之後進行驗證,如果驗證失敗,則嘗試重新建立連接(The indication of whether objects will be validated after creation. If the object fails to validate, the borrow attempt that triggered the object creation will fail.)

testOnBorrow

true

指明是否在從池中取出連接前進行檢驗,如果檢驗失敗,則從池中去除連接並嘗試取出另一個. 註意: 設置為true後如果要生效,validationQuery參數必須設置為非空字符串(The indication of whether objects will be validated before being borrowed from the pool. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.)

testOnReturn

false

指明是否在歸還到池中前進行檢驗(The indication of whether objects will be validated before being returned to the pool.)

testWhileIdle

false

指明連接是否被空閑連接回收器(如果有)進行檢驗.如果檢測失敗,則連接將被從池中去除. 註意: 設置為true後如果要生效,validationQuery參數必須設置為非空字符串(The indication of whether objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.)

timeBetweenEviction-

RunsMillis

-1

在空閑連接回收器線程運行期間休眠的時間值,以毫秒為單位.如果設置為非正數,則不運行空閑連接回收器線程(The number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.)

numTestsPerEvictionRun

3

在每次空閑連接回收器線程(如果有)運行時檢查的連接數量(The number of objects to examine during each run of the idle object evictor thread (if any).)

minEvictableIdleTime-Millis

1000*60*30

連接在池中保持空閑而不被空閑連接回收器線程(如果有)回收的最小時間值，單位毫秒(The minimum amount of time an object may sit idle in the pool before it is eligable for eviction by the idle object evictor (if any).)

softMiniEvictableIdle- TimeMillis

-1

說明(The minimum amount of time a connection may sit idle in the pool before it is eligible for eviction by the idle connection evictor, with the extra condition that at least "minIdle" connections remain in the pool. When miniEvictableIdleTimeMillis is set to a positive value, miniEvictableIdleTimeMillis is examined first by the idle connection evictor - i.e. when idle connections are visited by the evictor, idle time is first compared against miniEvictableIdleTimeMillis (without considering the number of idle connections in the pool) and then against softMinEvictableIdleTimeMillis, including the minIdle constraint.)

maxConnLifetimeMillis

-1

說明(The maximum lifetime in milliseconds of a connection. After this time is exceeded the connection will fail the next activation, passivation or validation test. A value of zero or less means the connection has an infinite lifetime.)

logExpiredConnections

true

說明(Flag to log a message indicating that a connection is being closed by the pool due to maxConnLifetimeMillis exceeded. Set this property to false to suppress expired connection logging that is turned on by default.

connectionInitSqls

null

說明(A Collection of SQL statements that will be used to initialize physical connections when they are first created. These statements are executed only once - when the configured connection factory creates the connection.)

info

true

說明(True means that borrowObject returns the most recently used ("last in") connection in the pool (if there are idle connections available). False means that the pool behaves as a FIFO queue - connections are taken from the idle instance pool in the order that they are returned to the pool.)

poolPreparedState-ments

false

開啟池的prepared statement 池功能(Enable prepared statement pooling for this pool.)

maxOpenPreparedState-ments

unlimited

statement池能夠同時分配的打開的statements的最大數量, 如果設置為0表示不限制(The maximum number of open statements that can be allocated from the statement pool at the same time, or negative for no limit.)

NOTE - Make sure your connection has some resources left for the other statements. Pooling PreparedStatements may keep their cursors open in the database, causing a connection to run out of cursors, especially if maxOpenPreparedStatements is left at the default (unlimited) and an application opens a large number of different PreparedStatements per connection. To avoid this problem, maxOpenPreparedStatements should be set to a value less than the maximum number of cursors that can be open on a Connection.

accessToUnderlyingConnectionAllowed

false

控制PoolGuard是否容許獲取底層連接(Controls if the PoolGuard allows access to the underlying connection.) 默認false不開啟, 這是一個有潛在危險的功能, 不適當的編碼會造成傷害.(關閉底層連接或者在守護連接已經關閉的情況下繼續使用它).請謹慎使用,並且僅當需要直接訪問驅動的特定功能時使用.註意: 不要關閉底層連接, 只能關閉前面的那個. Default is false, it is a potential dangerous operation and misbehaving programs can do harmful things. (closing the underlying or continue using it when the guarded connection is already closed) Be careful and only use when you need direct access to driver specific extensions. NOTE: Do not close the underlying connection, only the original one.

removeAbandoned

false

標記是否刪除泄露的連接,如果他們超過了removeAbandonedTimout的限制.如果設置為true, 連接被認為是被泄露並且可以被刪除,如果空閑時間超過removeAbandonedTimeout. 設置為true可以為寫法糟糕的沒有關閉連接的程序修復數據庫連接. (Flags to remove abandoned connections if they exceed the removeAbandonedTimout. A connection is considered abandoned and eligible for removal if it has not been used for longer than removeAbandonedTimeout. Setting one or both of these to true can recover db connections from poorly written applications which fail to close connections.)

removeAbandonedTimeout

300

泄露的連接可以被刪除的超時值, 單位秒(Timeout in seconds before an abandoned connection can be removed.)

logAbandoned

false

標記當Statement或連接被泄露時是否打印程序的stack traces日誌。被泄露的Statements和連接的日誌添加在每個連接打開或者生成新的Statement,因為需要生成stack trace。(Flag to log stack traces for application code which abandoned a Statement or Connection. Logging of abandoned Statements and Connections adds overhead for every Connection open or new Statement because a stack trace has to be generated.)

abandonedUsageTracking

false

如果為true, 那麽連接池會記錄每個方法調用時候的堆棧信息以及廢棄連接的調試信息(If true, the connection pool records a stack trace every time a method is called on a pooled connection and retains the most recent stack trace to aid debugging of abandoned connections. There is significant overhead added by setting this to true.)

註:如果開啟"removeAbandoned",那麽連接在被認為泄露時可能被池回收. 這個機制在(getNumIdle() < 2)and (getNumActive() > getMaxActive() - 3)時被觸發. 舉例當maxActive=20, 活動連接為18,空閑連接為1時可以觸發"removeAbandoned".但是活動連接只有在沒有被使用的時間超過"removeAbandonedTimeout"時才被刪除,默認300秒.在resultset中遊歷不被計算為被使用.

If you have enabled removeAbandonedOnMaintenance or removeAbandonedOnBorrow then it is possible that a connection is reclaimed by the pool because it is considered to be abandoned. This mechanism is triggered when (getNumIdle() < 2) and (getNumActive() > getMaxTotal() - 3) and removeAbandonedOnBorrow is true; or after eviction finishes and removeAbandonedOnMaintenance is true. For example, maxTotal=20 and 18 active connections and 1 idle connection would trigger removeAbandonedOnBorrow, but only the active connections that aren‘t used for more then "removeAbandonedTimeout" seconds are removed (default 300 sec). Traversing a resultset doesn‘t count as being used. Creating a Statement, PreparedStatement or CallableStatement or using one of these to execute a query (using one of the execute methods) resets the lastUsed property of the parent connection.

屬性(Parameter)

默認值(Default)

描述(Description)

user

同DBCP中的username屬性

password

同DBCP中的password屬性

jdbcUrl

同DBCP中的jdbcUrl屬性

driverClass

同DBCP中的driverClass屬性

autoCommitOnClose

false

默認值false表示回滾任何未提交的任務,設置為true則全部提交,而不是在關閉連接之前回滾

(C3P0‘s default policy is to rollback any uncommitted, pending work. Setting autoCommitOnClose to true causes uncommitted pending work to be committed, rather than rolled back on Connection close.)

*參見DBCP中的defaultAutoCommit屬性

initialPoolSize

3

初始化連接:連接池啟動時創建的初始化連接數量(The initial number of connections that are created when the pool is started.

*參見DBCP中的initialSize屬性

maxPoolSize

15

連接池中保留的最大連接數(Maximum number of Connections a pool will maintain at any given time.) *參見DBCP中的maxIdle屬性

minPoolSize

3

連接池中保留的最小連接數(Minimum number of Connections a pool will maintain at any given time.) *參見DBCP中的maxIdle屬性

maxIdleTime

0

最大等待時間:當沒有可用連接時,連接池等待連接被歸還的最大時間(以秒計數),超過時間則拋出異常,如果設置為0表示無限等待(Seconds a Connection can remain pooled but unused before being discarded. Zero means idle connections never expire.) *參見DBCP中maxWaitMillis 屬性

preferredTestQuery

null

定義所有連接測試都執行的測試語句。在使用連接測試的情況下這個一顯著提高測試速度。註意：測試的表必須在初始數據源的時候就存在。(Defines the query that will be executed for all connection tests, if the default ConnectionTester (or some other implementation of QueryConnectionTester, or better yet FullQueryConnectionTester) is being used. Defining a preferredTestQuery that will execute quickly in your database may dramatically speed up Connection tests.)

testConnectionOn- Checkin

false

如果設為true那麽在取得連接的同時將校驗連接的有效性。(If true, an operation will be performed asynchronously at every connection checkin to verify that the connection is valid. Use in combination with idleConnectionTestPeriod for quite reliable, always asynchronous Connection testing.) *參見DBCP中的testOnBorrow屬性

testConnectionOn- Checkout

false

如果設為true那麽在每個connection提交的時候都將校驗其有效性,但是要確保配置的preferredTestQuery的有效性(If true, an operation will be performed at every connection checkout to verify that the connection is valid. Be sure to set an efficient preferredTestQuery or automaticTestTable if you set this to true.) *參見DBCP中的testOnBorrow屬性

idleConnectionTest- Period

0

如果設置大於0,表示過了多少秒檢查一次空閑連接,結合testConnectionOnCheckin以及testConnectionOnCheckout使用(If this is a number greater than 0, c3p0 will test all idle, pooled but unchecked-out connections, every this number of seconds.)

acquireRetryAttempts

30

定義在從數據庫獲取新連接失敗後重復嘗試的次數, 如果小於0則表示無限制的連接。(Defines how many times c3p0 will try to acquire a new Connection from the database before giving up. If this value is less than or equal to zero, c3p0 will keep trying to fetch a Connection indefinitely.)

acquireRetryDelay

1000

兩次連接中的間隔時間，單位毫秒。(Milliseconds, time c3p0 will wait between acquire attempts.)

breakAfterAcquire-

Failure

false

獲取連接失敗將會引起所有等待連接池來獲取連接的線程拋出異常。但是數據源仍有效保留，並在下次調用 getConnection() 的時候繼續嘗試獲取連接。如果為 true，那麽在嘗試獲取連接失敗後該數據源將聲明已斷開並永久關閉。(If true, a pooled DataSource will declare itself broken and be permanently closed if a Connection cannot be obtained from the database after making acquireRetryAttempts to acquire one. If false, failure to obtain a Connection will cause all Threads waiting for the pool to acquire a Connection to throw an Exception, but the DataSource will remain valid, and will attempt to acquire again following a call to getConnection().)

checkoutTimeout

0

當連接池用完時客戶端調用 getConnection() 後等待獲取新連接的時間，潮濕後將拋出SQLException，如設為0，則為無限期等待。單位毫秒。(The number of milliseconds a client calling getConnection() will wait for a Connection to be checked-in or acquired when the pool is exhausted. Zero means wait indefinitely. Setting any positive value will cause the getConnection() call to time-out and break with an SQLException after the specified number of milliseconds.)

maxStatements

0

控制數據源內加載的PreparedStatements數量(Enable prepared statement pooling for this pool.)

maxStatementsPer- Connection

0

定義了連接池內單個連接所擁有的最大緩存statements數(The maximum number of open statements that can be allocated from the statement pool at the same time, or negative for no limit.)

屬性(Parameter)

默認值(Default)

描述(Description)

username

連接數據庫的用戶名

password

連接數據庫的密碼

jdbcUrl

同DBCP中的jdbcUrl屬性

driverClassName

根據url自動識別

這一項可配可不配，如果不配置druid會根據url自動識別dbType，然後選擇相應的driverClassName

initialSize

0

初始化時建立物理連接的個數。初始化發生在顯示調用init方法，或者第一次getConnection時 *參見DBCP中的initialSize屬性

maxActive

8

最大連接池數量(Maximum number of Connections a pool will maintain at any given time.) *參見DBCP中的maxTotal屬性

maxIdle

8

已經不再使用，配置了也沒效果 *參見DBCP中的maxIdle屬性

minIdle

最小連接池數量

maxWait

獲取連接時最大等待時間，單位毫秒。配置了maxWait之後，缺省啟用公平鎖，並發效率會有所下降，如果需要可以通過配置useUnfairLock屬性為true使用非公平鎖。

poolPreparedState- ments

false

是否緩存preparedStatement，也就是PSCache。PSCache對支持遊標的數據庫性能提升巨大，比如說oracle。

maxOpenPrepared- Statements

-1

要啟用PSCache，必須配置大於0，當大於0時，poolPreparedStatements自動觸發修改為true。 在Druid中，不會存在Oracle下PSCache占用內存過多的問題，可以把這個數值配置大一些，比如說100

testOnBorrow

true

申請連接時執行validationQuery檢測連接是否有效，做了這個配置會降低性能。

testOnReturn

false

歸還連接時執行validationQuery檢測連接是否有效，做了這個配置會降低性能

testWhileIdle

false

建議配置為true，不影響性能，並且保證安全性。申請連接的時候檢測，如果空閑時間大於timeBetweenEvictionRunsMillis，執行validationQuery檢測連接是否有效。

validationQuery

用來檢測連接是否有效的sql，要求是一個查詢語句。如果validationQuery為null，testOnBorrow、testOnReturn、testWhileIdle都不會其作用。在mysql中通常為select ‘x‘，在oracle中通常為select 1 from dual

timeBetweenEviction-RunsMillis

1) Destroy線程會檢測連接的間隔時間 2) testWhileIdle的判斷依據

minEvictableIdle- TimeMillis

Destory線程中如果檢測到當前連接的最後活躍時間和當前時間的差值大於minEvictableIdleTimeMillis，則關閉當前連接。

removeAbandoned

對於建立時間超過removeAbandonedTimeout的連接強制關閉

removeAbandoned-Timeout

指定連接建立多長時間就需要被強制關閉

logAbandoned

false

指定發生removeabandoned的時候，是否記錄當前線程的堆棧信息到日誌中

filters

屬性類型是字符串，通過別名的方式配置擴展插件，常用的插件有： 1）監控統計用的filter:stat 2）日誌用的filter:log4j 3）防禦sql註入的filter:wall