Dbcp连接MySQL

1.DBCP简介
DBCP(DataBase connection pool)数据库连接池是 apache 上的一个Java连接池项目。DBCP通过连接池预先同数据库建立一些连接放在内存中(即连接池中)，应用程序需要建立数据库连接时直接到从接池中申请一个连接使用，用完后由连接池回收该连接，从而达到连接复用，减少资源消耗的目的。
2.DBCP依赖的jar包
commons-dbcp2-2.1.1.jar commons-logging-1.2.jar commons-pool2-2.4.2.jar
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3.采用properties文件配置dbcp
properties文件采用的是key=value形式储存的，通过**getProperty(key)**获取value值
properties工具类

public class PropertiesUtil {
public static String getProperties(String key,String filename){
	Properties p = new Properties();
	InputStream is = null;
	String property = null;
	try {
		is = PropertiesUtil.class.getClassLoader().getResourceAsStream(filename);//创建输入流
		p.load(is);//加载输入流
		property = p.getProperty(key);//利用key获取value
	} catch (FileNotFoundException e) {
		e.printStackTrace();
	} catch (IOException e) {
		e.printStackTrace();
	}finally{
	is.close();
	}
	return property;
}

public static void setProperties(String key,String value,String filename){
	Properties p = new Properties();
	String path = null;
	try {
	path = URLDecoder.decode(PropertiesUtil.class.getClassLoader().getResource(filename).getPath(),"utf-8");url解码
	} catch (UnsupportedEncodingException e1) {
		e1.printStackTrace();
	}
	FileOutputStream fos = null;
	try {
		fos = new FileOutputStream(path,true);
		p.setProperty(key, value);//设置值
		p.store(fos, "123");//设置备注
		
	} catch (IOException e) {
		e.printStackTrace();
	}finally{
	fos.close();
	}
}
}

配置连接池

public class Dbcp {

	private static Dbcp dbcp;
	private static BasicDataSource bdSource;
	
	static{
		bdSource = new BasicDataSource();
		String filename = "jdbc.properties";
		bdSource.setUsername(PropertiesUtil.getProperties("user", filename));//数据库用户名
		bdSource.setPassword(PropertiesUtil.getProperties("password", filename));//密码
		bdSource.setUrl(PropertiesUtil.getProperties("url", filename));//url地址
		bdSource.setDriverClassName(PropertiesUtil.getProperties("driver", filename));//驱动名
		bdSource.setMinIdle(Integer.valueOf(PropertiesUtil.getProperties("minIdle", filename)));最小连接数
		bdSource.setMaxIdle(Integer.valueOf(PropertiesUtil.getProperties("maxIdle", filename)));最大连接数
		bdSource.setInitialSize(Integer.valueOf(PropertiesUtil.getProperties("initialSize", filename)));初始化连接数
		bdSource.setMaxWaitMillis(Integer.valueOf(PropertiesUtil.getProperties("maxWaitMillis", filename)));最大等待时间
	}
	public static Connection getConnection(){//提供连接
		Connection conn =  null;
		try {
			conn = bdSource.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
}