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Topic: Struts 数据源配置和使用

1.Struts 数据源配置和使用

Posted by: glistar
Posted on: 2003-03-17 11:12

（1）。单数据源配置
如果系统中只有一个数据源的情况下：
以下以 PostgreSQL 为例，配置文件如下，
<data-sources>
<data-source>
<set-property property="type" value="javax.sql.DataSource" />
<set-property property="driverClass" value="org.postgresql.Driver" />
<set-property property="url" value="jdbc:postgresql://DBServer:5432/DBName" />
<set-property property="maxCount" value="20" />
<set-property property="minCount" value="2" />
<set-property property="user" value="userName" />
<set-property property="password" value="userPassword" />
</data-source>
</data-sources>
在Action中调用：
DataSource ds = this.getDataSource(request);
这样就可以取得以上配置的数据源，然后再取连接。
注意：
A.上述的数据源取得方法只适用于配置了单个数据源。
B.连接用后一定要调用 close()方法，以将连接返回连接池中，已备重用。

（2）。多数据源配置
多数据源配置中，在 Easy－Struts 和其他的图形化配置工具中，目前都有问题，主要是 Struts 配置文件的 DTD 已经改过。
以下再提供 MySQL 数据源和 PostgreSQL 数据源为例，参见配置如下：

<data-sources>
<data-source>
<set-property property="key" value="postDS" />
<set-property property="type" value="javax.sql.DataSource" />
<set-property property="driverClass" value="org.postgresql.Driver" />
<set-property property="url" value="jdbc:postgresql://DBServer:5432/DBName" />
<set-property property="maxCount" value="20" />
<set-property property="minCount" value="2" />
<set-property property="user" value="userName" />
<set-property property="password" value="userPassword" />
</data-source>
<data-source>
<set-property property="key" value="mysqlDS" />
<set-property property="type" value="javax.sql.DataSource" />
<set-property property="driverClass" value="com.mysql.jdbc.Driver" />
<set-property property="url" value="jdbc:mysql://DBServer:3306/DBName" />
<set-property property="maxCount" value="20" />
<set-property property="minCount" value="2" />
<set-property property="user" value="userName" />
<set-property property="password" value="userPassword" />
</data-source>
</data-sources>

在Action中调用：
//MySQL 数据源取得
DataSource mysqlds = this.getDataSource(request,"mysqlDS");
//PostgreSQL 数据源取得
DataSource postds = this.getDataSource(request,"postDS");
连接的使用和注意事项同（1）。

有些书籍中不建议在 Action 中直接调用数据源，我觉得未尝不可。
本人已经做过压力测试，在Action中进行对数据库的频频操作，
当有 500 用户在线压力 30 分钟，未见任何异常。
测试，

如有遗漏，请多指教。

2.Re:Struts 数据源配置和使用 [Re: glistar]	Copy to clipboard
Posted by: dapan Posted on: 2003-03-17 12:35 不错！不过我一般自己做DBSource。 ^_^

3.Re:Struts 数据源配置和使用 [Re: glistar]

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Posted by: floater
Posted on: 2003-03-19 03:39

glistar wrote:

有些书籍中不建议在 Action 中直接调用数据源，我觉得未尝不可。
本人已经做过压力测试，在Action中进行对数据库的频频操作，
当有 500 用户在线压力 30 分钟，未见任何异常。
测试，

如有遗漏，请多指教。

I personally think the load is not the reason not use db source in action, but the seperation of them is the reason.

4.Re:Struts 数据源配置和使用 [Re: glistar]	Copy to clipboard
Posted by: glistar Posted on: 2003-03-19 09:13 There exists a separation between view and model,why separate the datasource from action? Struts developers hope we gain datasource from actions,you can read source codes!

5.Re:Struts 数据源配置和使用 [Re: glistar]

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Posted by: arjooe
Posted on: 2003-03-21 15:56

在我的Web Service中，我没有使用Struts中Action提供的getDataSource(request)方法来取得Connection, 我利用Jakarta.Commons的DBCP包写了一个Plugin,在ActionServlet初始化时将此连接池对象存在ServletContext中, 以利用它的Pooling Connection特性. 在Action中, 我们使用该对象的getConnection()方法来操作数据库.

我不知道Struts的DataSource本身是否有Connection Pool之功能, 请大家指教.

代码如下:
package bss.plugin;

/**
*
* @author pms24133
*/

import java.util.Iterator;
import java.util.Vector;
import javax.sql.DataSource;
import javax.servlet.ServletContext;

import org.apache.struts.action.Action;
import org.apache.struts.action.PlugIn;
import org.apache.struts.config.ApplicationConfig;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.config.DataSourceConfig;

import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.GenericObjectPool;
import org.apache.commons.dbcp.ConnectionFactory;
import org.apache.commons.dbcp.DataSourceConnectionFactory;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.dbcp.PoolingDataSource;

public class DBCPplugin implements PlugIn {

private ActionServlet servlet = null;

private Vector dbcpvtr = new Vector();

private String[] dskey = null;

public void destroy(){
// Remove all physical connections represented by datasource stored in ServletContex.

Iterator itr = dbcpvtr.iterator();
while(itr.hasNext()){
try{
GenericObjectPool gop = (GenericObjectPool)itr.next();
gop.close();
gop = null;
}catch(Exception e){
servlet.log("System errors::::" + e);
}finally{
}
}

this.dbcpvtr = null;

for(int i =0; i<dskey.length; i++){
PoolingDataSource pds = (PoolingDataSource) (servlet.getServletContext().
getAttribute(dskey[i]));
pds = null;
}

dskey = null;
}

public void init(ActionServlet servlet,ApplicationConfig config){
// Data Sources configed in /WEB-INF/struts-config.xml,
// and can be retrieved through config.findDatasourceConfigs() in DataSourceConfig object format;
// We assign data from these configs to DBCP config.
this.servlet = servlet;

DataSourceConfig dscs[] = config.findDataSourceConfigs();

if (dscs == null) {
dscs = new DataSourceConfig[0];
servlet.log("No DataSource configed yet.");
}

this.dskey = new String[dscs.length];

// Process each DataSource config according key.
for( int i = 0; i < dscs.length; i++){
// Retrieve each DataSource from ActionServlet Context,
DataSource ds = (DataSource) servlet.getServletConfig().getServletContext().getAttribute( dscs[i].getKey() );

// Define a connection Pool for this Data Source definition,

//ObjectPool connectionPool = new GenericObjectPool(connectionFactory);
ObjectPool connectionPool = new GenericObjectPool(null);

// Construct a Conneciton Factory for this Data Source,
ConnectionFactory connectionFactory =
new DataSourceConnectionFactory(ds);

// Construct connectionpool with connection factory

try{

PoolableConnectionFactory poolableConnectionFactory =
new PoolableConnectionFactory(connectionFactory,
connectionPool,
null,
null,
false,
true);

/*
* Parameter definition of constructor method of PoolableConnectionFactory
*
* connectionFactory - the ConnectionFactory from which to obtain base Connections
* connectionPool - the ObjectPool in which to pool those Connections
* stmtPoolFactory - the KeyedObjectPoolFactory to use to create KeyedObjectPools for pooling PreparedStatements, or null to disable PreparedStatement pooling
* validationQuery - a query to use to validate Connections. Should return at least one row. May be null
* defaultReadOnly - the default "read only" setting for borrowed Connections
* defaultAutoCommit - the default "auto commit" setting for returned Connections
*/

PoolingDataSource dataSource = new PoolingDataSource(connectionPool);

// Store connectionpool to Application Context for further globle use;
servlet.getServletContext().setAttribute( dscs[i].getKey(),dataSource);
dbcpvtr.add(connectionPool);

servlet.log("Store org.apache.commons.dbcp.PoolingDataSource with key '"+ dscs[i].getKey() + "' to Application Context.");
}catch(Exception e){
servlet.log("Initiating Datasource error: " + e.toString() );
}
}
}//End of init method

}//End of class

6.Re:Struts 数据源配置和使用 [Re: arjooe]	Copy to clipboard
Posted by: glistar Posted on: 2003-03-21 16:02 Struts 利用 commons-dbcp.jar 包主要就是完成连接池功能的. 因此你不必自己写连接功能,而是直接按照第一贴的内容配置和使用就可以!

7.Re:Struts 数据源配置和使用 [Re: glistar]	Copy to clipboard
Posted by: arjooe Posted on: 2003-03-21 17:21 谢谢!

8.Re:Struts 数据源配置和使用 [Re: glistar]

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Posted by: floater
Posted on: 2003-03-25 01:13

glistar wrote:
There exists a separation between view and model,why separate the datasource from action? Struts developers hope we gain datasource from actions,you can read source codes!

action is in C, db is in M. That's why I diff.

I loaded their code into jb and read them last year. My impression with their source code was they started with pre-mature code, and have to carry them all the way along.

9.Re:Struts 数据源配置和使用 [Re: glistar]	Copy to clipboard
Posted by: lihongtao Posted on: 2003-03-25 09:04 我也不赞成在Action里面写业务逻辑