上一篇文章简单介绍了数据库连接池的基本原理实现，链接：数据库连接池的简单实现这里我们介绍两种常用数据库连接池的使用：
1.DBCP数据库连接池：
package com.itheima.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.commons.dbcp.BasicDataSource;
public class DBCPDemo {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
BasicDataSource source = new BasicDataSource();
source.setDriverClassName("com.mysql.jdbc.Driver");
source.setUrl("jdbc:mysql://localhost:3306/day11");
source.setUsername("root");
source.setPassword("root");
conn = source.getConnection();
ps = conn.prepareStatement("select * from account");
rs = ps.executeQuery();
while(rs.next()) {
String name = rs.getString(2);
String salary = rs.getString(3);
System.out.println(name + " : " + salary);
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
rs = null;
}
}
if(ps != null) {
try {
ps.close();
} catch (SQLException e) {
ps = null;
}
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
conn = null;
}
}
}
}
}
这里需要导入相应的dbcp jar包，这里我就不提供了。
以上代码是通过set方法设置类加载路径、url、数据库用户名和密码，此外我们还可以通过properties文件进行配置。
properties文件内的属性名称和setXXX方法对应，只是首字母小写。
dbcp-config.properties文件内容如下：
#类加载路径 driverClassName=com.mysql.jdbc.Driver #url数据库访问路径 url=jdbc:mysql://localhost:3306/day11 #用户名 username=root #密码 password=root
package com.itheima.jdbc;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
public class DBCPDemo {
private static Properties properties = new Properties();
static {
try {
properties.load(new FileReader("dbcp-config.properties"));
} catch (FileNotFoundException e) {
e.printStackTrace();
throw new RuntimeException(e);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
BasicDataSourceFactory factory = new BasicDataSourceFactory();
DataSource source = factory.createDataSource(properties);
conn = source.getConnection();
ps = conn.prepareStatement("select * from account");
rs = ps.executeQuery();
while(rs.next()) {
String name = rs.getString(2);
String salary = rs.getString(3);
System.out.println(name + " : " + salary);
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
rs = null;
}
}
if(ps != null) {
try {
ps.close();
} catch (SQLException e) {
ps = null;
}
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
conn = null;
}
}
}
}
}
此外dbcp-config.properties文件内还可以配置一下属性
#数据库连接池初始化连接数 initialSize=10 #数据库连接池最大连接数 maxActive=50 #数据库连接池最小空闲连接数 minIdle=5 #数据库连接池最大空闲连接数 maxIdle=20 #等待超时，当一个链接空闲时间超过该时间，该链接定义为空闲连接 maxWait=60000
2.c3p0数据库连接池
package com.itheima.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Demo {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
ComboPooledDataSource source = new ComboPooledDataSource();
source.setDriverClass("com.mysql.jdbc.Driver");
source.setJdbcUrl("jdbc:mysql://localhost:3306/day11");
source.setUser("root");
source.setPassword("root");
conn = source.getConnection();
ps = conn.prepareStatement("select * from account");
rs = ps.executeQuery();
while(rs.next()) {
String name = rs.getString(2);
String salary = rs.getString(3);
System.out.println(name + " : " + salary);
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
rs = null;
}
}
if(ps != null) {
try {
ps.close();
} catch (SQLException e) {
ps = null;
}
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
conn = null;
}
}
}
}
}
相应的可以通过配置c3p0-config.xml文件
以下是官方文档的叙述：
By default, c3p0 will look for an XML configuration file in its classloader‘s resource path under the name "/c3p0-config.xml". That means the XML file should be placed in a directly or jar file directly named in your applications CLASSPATH, in WEB-INF/classes,
or some similar location.
（也就是说：名字必须为c3p0-config.xml，文件位置：类加载路径下，即eclipse的src目录下）
package com.itheima.jdbc;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0Demo {
public static void main(String[] args) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
try {
//如果不通过setXXX方法设置属性，则会自动到类加载目录下查找c3p0-config.xml文件
//查找到后默认使用<default-config>标签下的配置信息，也可以在构造source对象时传入
//配置的名称，即ComboPooledDataSource source = new ComboPooledDataSource("myconfig");
//当然c3p0-config.xml文件里配置了<default-config>和<named-config>,一般情况下使用其中一个就行了。
ComboPooledDataSource source = new ComboPooledDataSource();
conn = source.getConnection();
ps = conn.prepareStatement("select * from account");
rs = ps.executeQuery();
while(rs.next()) {
String name = rs.getString(2);
String salary = rs.getString(3);
System.out.println(name + " : " + salary);
}
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
} finally {
if(rs != null) {
try {
rs.close();
} catch (SQLException e) {
rs = null;
}
}
if(ps != null) {
try {
ps.close();
} catch (SQLException e) {
ps = null;
}
}
if(conn != null) {
try {
conn.close();
} catch (SQLException e) {
conn = null;
}
}
}
}
}
c3p0-config.xml:
<?xml version="1.0" encoding="utf-8"?>
<c3p0-config>
<default-config>
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/day11</property>
<property name="user">root</property>
<property name="password">root</property>
</default-config>
<named-config name="myconfig">
<property name="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl">jdbc:mysql://localhost:3306/day11</property>
<property name="user">root</property>
<property name="password">root</property>
</named-config>
</c3p0-config>
<default-config>和<named-config>两者只配置一个就可以了
此外xml文件还可以配置其他参数，这里就不一一赘述了，官方文档写的很清楚。
时间： 2024-10-13 13:00:50