java 使用 c3p0 池连接数据库 mysql
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connecting database mysql using c3p0 pooling
提问by Arjun K P
ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "com.mysql.jdbc.Driver" ); //loads the jdbc driver
cpds.setJdbcUrl( "jdbc:mysql://localhost:3306/dragon" );
cpds.setUser("root");
cpds.setPassword("password");
cpds.setMaxPoolSize(50);
I've created a java file containing the following code to configure a ComboPooledDataSource object. Now is this code enough to establish a pooled connection with the database?
我创建了一个包含以下代码的 java 文件来配置 ComboPooledDataSource 对象。现在这段代码足以建立与数据库的池连接吗？
If not, What else should I do ?
如果没有，我还应该做什么？
Also please tell how can I can implement JNDI here.
另外请告诉我如何在这里实现 JNDI。
Please explain it since I am a beginner.
由于我是初学者，请解释一下。
回答by Arjun K P
At First...Create the code to initiate the connection in a class containing static methods or variables like this the following..
首先...创建代码以在包含静态方法或变量的类中启动连接，如下所示..
private static ComboPooledDataSource cpds = new ComboPooledDataSource();
public static void MakePool()
{
try
{
cpds=new ComboPooledDataSource();
cpds.setDriverClass("com.mysql.jdbc.Driver");
cpds.setJdbcUrl("jdbc:mysql://localhost:3306/att_db");
cpds.setUser("root");
cpds.setPassword("dragon");
cpds.setMaxPoolSize(MaxPoolSize);
cpds.setMinPoolSize(MinPoolSize);
cpds.setAcquireIncrement(Accomodation);
}
catch (PropertyVetoException ex)
{
//handle exception...not important.....
}
}
public static Connection getConnection()
{
return cpds.getConnection();
}
Once u r done Create another class meant for server operations....
完成后创建另一个用于服务器操作的类....
and get the Connections from the Pool...
并从池中获取连接...
try{
con=DatabasePool.getConnection();
// DatabasePool is the name of the Class made earlier....
.
.
.
. // Server operations as u wanted.....
.
.
}
catch(SQL EXCEPTION HERE)
{
.....
}
finally
{
if(con!=null)
{
con.close();
}
}
回答by janoside
I'm not familiar with JNDI so I won't address that (you probably want a separate question for that with more detail about your goal), but I believe you do have your ComboPooledDataSource configured properly.
我不熟悉 JNDI，所以我不会解决这个问题（您可能需要一个单独的问题，其中包含有关您的目标的更多详细信息），但我相信您确实正确配置了 ComboPooledDataSource。
You should be able to test your DataSource using code like this (exception handling excluded for simplicity):
您应该能够使用这样的代码来测试您的数据源（为简单起见，排除了异常处理）：
ArrayList<Object[]> data = new ArrayList<Object[]>();
Connection connection = cpds.getConnection();
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("select a_column from a_table;");
int columnCount = resultSet.getMetaData().getColumnCount();
while (resultSet.next()) {
Object[] rowData = new Object[columnCount];
for (int i = 0; i < columnCount; i++) {
rowData[i] = resultSet.getObject(i + 1);
}
data.add(rowData);
}
回答by jiangwh
You use the c3p0 to manage the jdbc connection and should not use the jdni. If you want use the jndi , you need config the connection in the web container. Tomcat like
您使用 c3p0 来管理 jdbc 连接，不应使用 jdni。如果要使用 jndi ，则需要在 Web 容器中配置连接。像Tomcat一样
<Context>
<Resource name="jdbc/springflow" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000" username="root"
password="" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/test" />
</Context>
And you can use jndi like context.lookup("java:jdbc/springflow").
你可以使用 jndi 之类的context.lookup("java:jdbc/springflow")。
