【JDBC连接池C3P0(一)（使用properties文件进行配置）】1、在src下新建一个properties文件，名字随便符合命名规范即可，我这里的名称为：c3p0config.properties，内容如下：
jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://127.0.0.1:3306/test jdbc.username=root jdbc.pwd=root
2、新建类进行连接测试：
public class DBConnectionByC3P0 {
private static String url = null;
private static String username = null;
private static String pwd = null;
private static DataSource ds_pooled;
//私有构造方法，不能创建对象
private DBConnectionByC3P0(){ } //加载数据库连接的配置文件和驱动
static{
Properties env = new Properties();
try {
InputStream in = DBConnectionByC3P0.class.getResourceAsStream("/c3p0config.properties");
//加载属性文件中的数据库配置信息
//以=左边作为key值，右边作为value值
env.load(in);
//1. 加载驱动类
Class.forName(env.getProperty("jdbc.driver"));
url = env.getProperty("jdbc.url");
username = env.getProperty("jdbc.username");
pwd = env.getProperty("jdbc.pwd");
//2、设置连接数据库的配置信息
DataSource ds_unpooled = DataSources.unpooledDataSource(url, username, pwd);
Map pool_conf = new HashMap();
//3、设置最大连接数
pool_conf.put("maxPoolSize", 10);
ds_pooled = DataSources.pooledDataSource(ds_unpooled,pool_conf);
} catch (Exception e) {
e.printStackTrace();
}
}
//获取连接对象
public static Connection getConnection() throws SQLException {
return ds_pooled.getConnection();
}
//释放连接池资源
public static void clearup(){
if(ds_pooled != null){
try {
DataSources.destroy(ds_pooled);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
private static Integer counter = 0;
public static void main(String[] args){
for (int i = 1;
i <= 20;
i++) {
new Thread(new Runnable() {
public void run() {
Connection conn = null;
try {
conn = DBConnectionByC3P0.getConnection();
synchronized (counter) {
System.out.print(Thread.currentThread().getName());
System.out.print("counter=" +(counter++)+ "\tconn="+conn);
System.out.println();
conn.prepareStatement("select * from s_user");
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}).start();
}
}
}
