catalogue

1.C3P0

Preparation before use:

Method 1: hard coding (database configuration is written into the code)

Method 2: write configuration file and separate code and configuration (development recommendation)

2.DBCP

Preparation before use:

Method 1: hard coding (database configuration is written into the code)

Method 2: write configuration file and separate code and configuration (development recommendation)

3. Druid (Druid)

Preparation before use:

Upper code

1.C3P0

Preparation before use:

Download the jar package from the official website

c3p0-v0.9.5.5 - JDBC3 Connection and Statement Pooling - Documentation (mchange.com)

Note that it is bin zip 

 

After that, go to this path and copy the two jar packages

 

Create a new folder under the project

 

Copy the jar package here

CTRL select two jar packages and right click

 

 

You can choose either project or module. Let's choose the module library and click OK

 

New test class test

 

Method 1: hard coding (database configuration is written into the code)

This article uses the @ Test unit Test method to Test. If you haven't seen it, you can replace it with the main method

@Test
public void getConnection() throws PropertyVetoException, SQLException {
        //Get c3p0 database connection pool
        ComboPooledDataSource cpds = new ComboPooledDataSource();

        cpds.setDriverClass("com.mysql.cj.jdbc.Driver"); //JDBC driver loading
        cpds.setJdbcUrl("jdbc:mysql://localhost:3306/test");//test corresponds to a table in your database
        cpds.setUser("root");//user name
        cpds.setPassword("admin");//password
       
        Connection cn = cpds.getConnection();//Get database connection
        System.out.println(cn);

        DataSources.destroy(cpds);//Destroy connection pool
}

Operation results: (note that red is the log information, not an error)

Method 2: write configuration file and separate code and configuration (development recommendation)

Create a file under src. The file name (specified by the connection pool cannot be changed)

c3p0-config.xml

The contents of the XML file are as follows

<?xml version="1.0" encoding="UTF-8" ?>
<c3p0-config>
    <!-- Provides four basic information for obtaining connections -->
    <named-config name="helloC3P0">
        <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
        <property name="user">root</property>
        <property name="password">admin</property>
    </named-config>
</c3p0-config>

among

<named-config name="helloC3P0">

name can be customized

Let's write the code again (write the name just customized in the constructor)

    @Test
    public void getConnection2() throws SQLException {
        ComboPooledDataSource cpds = new ComboPooledDataSource("helloC3P0");
        Connection cn = cpds.getConnection();
        System.out.println(cn);
        DataSources.destroy(cpds);
    }

Operation results:

 

2.DBCP

Preparation before use:

Download jar packages from the official website (3)

1.

DBCP – Overview (apache.org)

Note: Java 8 is the minimum required version

 

2.

Pool – Download Apache Commons Pool

 

3.

Apache Commons Logging - Download Apache Commons Logging

 

These three bags

 

 

 

Put the jar package in the lib directory and add it as a library (other steps are the same as above, omitted)

 

Method 1: hard coding (database configuration is written into the code)

    @Test
    public void testDBCP() throws SQLException {
        BasicDataSource source = new BasicDataSource();
        source.setDriverClassName("com.mysql.cj.jdbc.Driver");
        source.setUrl("jdbc:mysql://localhost:3306/test");
        source.setUsername("root");
        source.setPassword("admin");

        Connection cn = source.getConnection();
        System.out.println(cn);
    }

 

Method 2: write configuration file and separate code and configuration (development recommendation)

src right click

 

Note the initial lowercase

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///test
username=root
password=admin

test

@Test
public void test2() throws Exception {
    InputStream is = ClassLoader.getSystemClassLoader().
        getResourceAsStream("dbcp.properties");
    Properties pros = new Properties();
    pros.load(is);
    BasicDataSource source = BasicDataSourceFactory.createDataSource(pros);

    Connection cn = source.getConnection();
    System.out.println(cn);
}

Operation results:

3. Druid (Druid)

We use Ali's database connection pool Druid

 

Preparation before use:

Download the jar package from the official website

Central Repository: com/alibaba/druid/1.2.8 (maven.org)

 

Put the jar package in the lib directory and add it as a library (other steps are the same as above, omitted)

 

In order not to bother, write the second one directly

Create a druid under src properties

The configuration information is the same as DBCP properties

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///test
username=root
password=admin

Upper code

    @Test
    public void test() throws Exception {
        InputStream is = ClassLoader.getSystemResourceAsStream("druid.properties");
        Properties pros = new Properties();
        pros.load(is);
        DataSource source = DruidDataSourceFactory.createDataSource(pros);
        Connection cn = source.getConnection();
        System.out.println(cn);
    }