Before the text

In the previous article, we talked about the traditional JDBC Connect MySQL The way , But this way, when making multiple connections , It's inefficient , Obviously not as efficient as connection pooling , So let's talk about it this time JDBC One of the connection pools :c3p0


Text

1. preparation

  • IntelliJ IDEA
  • c3p0-0.9.5.2(jar)
  • MySQL

2. To configure c3p0-config.xml

default-config

Before configuration , You need to build a database first , This article still uses the name in the previous article as customer The database of

And then in Engineering src Create a new directory named c3p0-config Of XML file ( The file name cannot be customized )

Then start configuration :

 <!-- Database address -->
<property name="jdbcUrl">jdbc:mysql://localhost:3306/customer</property>
<!-- Database driven -->
<property name="driverClass">com.mysql.jdbc.Driver</property>
<!-- user name -->
<property name="user">root</property>
<!-- password -->
<property name="password">3865933</property>

Write basic database information first , Then we'll write the common connection pool properties , To query all properties , You can read the official website guide , Attributes are also included in :

 <!-- Number of connections created during connection pool initialization -->
<property name="initialPoolSize">1</property>
<!-- The minimum number of connections in the connection pool -->
<property name="minPoolSize">1</property>
<!-- The minimum number of connections in the connection pool -->
<property name="maxPoolSize">2</property>
<!-- When no idle connection is available , The number of new connections that can be created at one time -->
<property name="acquireIncrement">1</property>
<!-- Gets the number of repeated attempts after the database connection failed -->
<property name="acquireRetryAttempts">1</property>
<!-- The interval between two connections , The unit is millisecond -->
<property name = "acquireRetryDelay">1000</property>

Give a complete picture of the file :

named-config

You can add named-config To increase database configuration , Content and default-config Agreement , I connected to another database product :

3. Write a demo

Take care of the data source first :

 private static ComboPooledDataSource dataSource1 = new ComboPooledDataSource("test");
private static ComboPooledDataSource dataSource2 = new ComboPooledDataSource();

According to the data source , Connect

 private static void getConnection(){
try{
Connection connection = dataSource1.getConnection();
System.out.println(" Connect to database product success !");
connection.close();
System.out.println(" Database connection closed !");
}catch(Exception e){
System.out.println(" Failed to connect to database !");
}
try{
Connection connection = dataSource2.getConnection();
System.out.println(" Connect to database customer success !");
connection.close();
System.out.println(" Database connection closed !");
}catch(Exception e){
System.out.println(" Failed to connect to database !");
}
}
public static void main(String[] args){
getConnection();
}

Running results :

If multiple connections are needed , Using connection pooling is the best choice , About c3p0 This is the end of my explanation , thank you .

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