blocks|key|1475972|text|维护单个连接，甚至更好地使用连接池|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1475973|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Connection_pool^0|E|3|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Maintain a single connection or even better use <a href="http://en.wikipedia.org/wiki/Connection_pool" rel="nofollow">Connection-pooling</a>

blocks|key|1476003|text|在哪里可以找到好的说明或教程，说明如何将JDBC连接池连接到我的客户机上的Postgres数据库？|type|blockquote|depth|inlineStyleRanges|entityRanges|data|1476004|http://www.mchange.com/projects/c3p0/index.html|unstyled|offset|length|1476005|c3p0被设计成使用起来很简单。只需将jar文件lib/c3p0-0.9.0.jar放在应用程序的有效CLASSPATH中，并生成如下DataSource：|1476006|import+com.mchange.v2.c3p0.*;

...

ComboPooledDataSource+cpds+=+new+ComboPooledDataSource();
cpds.setDriverClass(+"org.postgresql.Driver"+);+//loads+the+jdbc+driver++++++++++++
cpds.setJdbcUrl(+"jdbc:postgresql://localhost/testdb"+);
cpds.setUser("dbuser");++++++++++++++++++++++++++++++++++
cpds.setPassword("dbpassword");++++|code-block|syntax|javascript|1476007|如果要打开PreparedStatement池，还必须设置maxStatements和/或maxStatementsPerConnection(两者都默认为0)：|style|CODE|1476008|cpds.setMaxStatements(+180+);+|1476009|对您的DataSource做您想做的任何事情，它将由一个带有默认参数的连接池来支持。您可以将DataSource绑定到JNDI服务，或者根据您的喜好直接使用它。完成之后，您可以像这样清理您创建的DataSource：|1476010|DataSources.destroy(+cpds+);|1476011|就这样!其余的都是细节。|1476012|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1B|0|0|0|0|5|H|T|D|19|Q|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|17|8|@]|9|@$E|18|F|19|1|1A]]|A|$]]|$1|G|3|H|5|D|7|1B|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|1C|8|@]|9|@]|A|$L|M]]|$1|N|3|O|5|D|7|1D|8|@$E|1E|F|1F|P|Q]|$E|1G|F|1H|P|Q]|$E|1I|F|1J|P|Q]]|9|@]|A|$]]|$1|R|3|S|5|K|7|1K|8|@]|9|@]|A|$L|M]]|$1|T|3|U|5|D|7|1L|8|@]|9|@]|A|$]]|$1|V|3|W|5|K|7|1M|8|@]|9|@]|A|$L|M]]|$1|X|3|Y|5|D|7|1N|8|@]|9|@]|A|$]]|$1|Z|3|-4|5|D|7|1O|8|@]|9|@]|A|$]]]|10|$11|$5|12|13|14|A|$15|C]]]]

<blockquote>
 Where can I find good instructions or a tutorial on how to do connection
 pooling for JDBC to a Postgres database on my client?
</blockquote>

<a href="http://www.mchange.com/projects/c3p0/index.html" rel="nofollow">http://www.mchange.com/projects/c3p0/index.html</a>

c3p0 was designed to be butt-simple to use. Just put the jar file 
[lib/c3p0-0.9.0.jar] in your application's effective CLASSPATH, and make a 
DataSource like this: 

<pre><code>import com.mchange.v2.c3p0.*;

...

ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "org.postgresql.Driver" ); //loads the jdbc driver 
cpds.setJdbcUrl( "jdbc:postgresql://localhost/testdb" );
cpds.setUser("dbuser"); 
cpds.setPassword("dbpassword"); 
</code></pre>

[Optional] If you want to turn on <code>PreparedStatement</code> pooling, you must also set 
<code>maxStatements</code> and/or <code>maxStatementsPerConnection</code>(both default to 0): 

<pre><code>cpds.setMaxStatements( 180 ); 
</code></pre>

Do whatever you want with your DataSource, which will be backed by a 
Connection pool set up with default parameters. You can bind the DataSource 
to a JNDI name service, or use it directly, as you prefer. 
 When you are done, you can clean up the DataSource you've created like this: 

<pre><code>DataSources.destroy( cpds );
</code></pre>

That's it! The rest is detail.

blocks|key|3030905|text|对一个模糊问题的模糊回答：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3030906|而是管理您的JDBC连接。如果打开的连接太多，则必须维护它们，并确保它们已关闭，以便其他连接访问数据库(您可以有一个异常，说明“打开的文件太多”)。连接池维护连接。每个请求有一个连接，一旦完成，就返回到池。|3030907|我会这么做：|3030908|在连接池中维护我的JDBC连接(谢谢吉加尔·乔希)。|unordered-list-item|offset|length|3030909|从连接池请求连接并在我的DAO中使用它(+DAO是我的对象对DB的CRUD+)。|3030910|连接完成后，将连接返回到connection。|3030911|如果使用Spring，请使用Spring模板。|3030912|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Connection_pool|1|https://stackoverflow.com/users/260990/jigar-joshi|2|http://en.wikipedia.org/wiki/Data_access_object|3|http://static.springsource.org/spring/docs/2.0.x/reference/jdbc.html^0|0|0|0|1|3|0|I|6|1|0|C|3|2|0|0|E|8|3|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|16|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|17|8|@]|9|@$I|18|J|19|1|1A]|$I|1B|J|1C|1|1D]]|A|$]]|$1|K|3|L|5|H|7|1E|8|@]|9|@$I|1F|J|1G|1|1H]]|A|$]]|$1|M|3|N|5|H|7|1I|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1J|8|@]|9|@$I|1K|J|1L|1|1M]]|A|$]]|$1|Q|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|Z]]|10|$5|T|U|V|A|$W|11]]|12|$5|T|U|V|A|$W|13]]]]

A vague answer for a vague question: 

Rather have your JDBC connections managed. If you have too many connections open, you will have to maintain them and make sure they're closed for other connections to access the database (you can have an Exception stating "Too many open files"). Connection Pooling maintains your connection. Have 1 connection per request and once you're done, return it back to the pool.

I would do this:

<ul>
<li>Have my JDBC connections maintained in a <a href="http://en.wikipedia.org/wiki/Connection_pool" rel="nofollow noreferrer">Connection Pool</a> (thanks <a href="https://stackoverflow.com/users/260990/jigar-joshi">Jigar Joshi</a>).</li>
<li>Request the connection from the Connection Pool and use it in my <a href="http://en.wikipedia.org/wiki/Data_access_object" rel="nofollow noreferrer">DAO</a> (the DAO is what does the CRUD of my object to DB).</li>
<li>Once connection is done, return the connection to the Connection Pool.</li>
</ul>

If you're using Spring, use the <a href="http://static.springsource.org/spring/docs/2.0.x/reference/jdbc.html" rel="nofollow noreferrer">Spring JDBC Template</a>.

I am manipulating a postgresql database with java. Please help me to choose a development practice.

Must I:

<ul>
<li>create a jdbc singleton object?</li>
<li>create a new connection for every request?</li>
<li>or use the jdbc api for spring framework?</li>
</ul>

Which is the best practice?

jdbc connection with java, singleton connection object or spring jdbc connection?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在使用java操作postgresql数据库。请帮助我选择一个开发实践。我必须：创建一个jdbc单例对象？为每个请求创建一个新的连接？还是使用jdbc作为spring框架？哪一种是最佳做法？

问用java、单例连接对象还是spring连接的jdbc连接？
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问用java、单例连接对象还是spring连接的jdbc连接？EN