Java DataSource 访问数据库

落日映苍穹つ 2022-08-23 05:48 152阅读 0赞

以前呢,我们是通过DriverManager这个类来的得到Connection对象的。

现在我们通过DataSource来得到Connection，

其余的都是一样的东西，

先上DataSource得到Connection的代码。

在这之前，先将db.properties配置文件的内容考进来

jdbc.datasource=com.mchange.v2.c3p0.ComboPooledDataSource
    jdbc.driverClass=com.mysql.jdbc.Driver
    jdbc.jdbcUrl=jdbc:mysql://localhost:3306/test
    jdbc.user=root
    jdbc.password=
    jdbc.maxPoolSize=100
    jdbc.minPoolSize=2
    jdbc.initialPoolSize=2
    jdbc.acquireIncrement=2
    jdbc.maxStatements=1000
    jdbc.maxIdleTime=300
    jdbc.checkoutTimeout=5000

获得的Connection的讲解全在代码注释上，

package org.test;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.util.Properties;
    
    import javax.sql.DataSource;
    
    import org.apache.commons.beanutils.BeanUtils;
    
    public class JdbcDataSourceTest
    {
    	private static DataSource dataSource;
    
    	private static Connection connection;
    
    	private static PreparedStatement ps;
    
    	private static ResultSet rs;
    
    	public static void main(String[] args) throws Exception
    	{
    
    		
    		
    		Properties properties = new Properties();
    
    		//从指定的配置文件加载数据到properties中
    		properties.load(JdbcDataSourceTest.class.getClassLoader().getResourceAsStream("db.properties"));
    
    		
    		/**
    		 * properties其中一条记录是这样的
    		 * jdbc.datasource=com.mchange.v2.c3p0.ComboPooledDataSource
    		 * 将前面的jdbc.去掉在重新装入一个Properties中
    		 */
    		Properties dbProperties = new Properties();
    
    		for (Object key : properties.keySet())
    		{
    			String temp = (String) key;
    
    			if (temp.startsWith("jdbc."))
    			{
    				String name = temp.substring(5);
    
    				dbProperties.put(name, properties.getProperty(temp));
    
    			}
    		}
    
    		//列出dbProperties中的所有属性
    		dbProperties.list(System.out);
    		
    		System.out.println("==============================================");
    
    		//从厂商提供的DataSource实现中加载其对象
    		dataSource = (DataSource) Class.forName(properties.getProperty("jdbc.datasource")).newInstance();
    
    		
    		//将dbProperties属性中的内容加入到dataSource对象中
    		BeanUtils.populate(dataSource, dbProperties);
    
    		
    		
    		connection = dataSource.getConnection();
    
    		ps = connection.prepareStatement("select * from test");
    
    		rs = ps.executeQuery();
    
    		while (rs.next())
    		{
    			System.out.println(rs.getString(1));
    		}
    	}
    }

再来就是上以前通过DriverManager来得到Connection的代码

package org.test;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    public class JdbcTest
    {
    	
    	private static Connection connection ;
    	
    	private static PreparedStatement ps ;
    	
    	private static ResultSet rs  ;
    	
    	static 
    	{
    		try
    		{
    			Class.forName("com.mysql.jdbc.Driver");
    		}
    		catch (ClassNotFoundException e)
    		{
    			e.printStackTrace();
    		}
    		
    		
    	}
    	
    	public static void main(String[] args) throws Exception
    	{
    		connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","");
    		
    		ps = connection.prepareStatement("select * from test");
    		
    		rs = ps.executeQuery();
    		
    		while (rs.next())
    		{
    			System.out.println(rs.getString(1));
    		}
    	}
    }