编写DBCP连接池

#配置数据库数据源
package com.itang.utils;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public class DBCPUtil {
	
	private static DataSource dataSource;
	static{
		try {
			InputStream in = DBCPUtil.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
			Properties props = new Properties();
			props.load(in);
			dataSource = BasicDataSourceFactory.createDataSource(props);
		} catch (Exception e) {
			e.printStackTrace();
			throw new ExceptionInInitializerError(e);
		}
	}
	
	public static DataSource getDataSource(){
		return dataSource;
	}
	public static Connection getConnection(){
		try {
			return dataSource.getConnection();
		} catch (SQLException e) {
			throw new RuntimeException(e);
		}
	}

/**
 * 功能：关闭数据库连接资源
 * @param rs 
 * ResultSet对象
 * @param st
 * Statement 对象
 * @param conn
 * Connection对象
 */
	public static void closeSource(ResultSet rs, Statement st, Connection conn)
	{
		if(rs!=null)
		{
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}finally {
				closeSource(st,conn);
			}
		}
	}
	
	public static void closeSource(Statement st, Connection conn) {
			if(st!=null)
			{
				try {
					st.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}finally {
					if(conn!=null)
					{
						try {
							conn.close();
						} catch (SQLException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
					}
				}
			}
	}
}

　　获取配置文件的属性值

public class GetDefaultValue {
	private static String defaultimagepath;
	private static String defaultimagename;
	static {
		ResourceBundle bundle=ResourceBundle.getBundle("defaultvalueconfig");
		defaultimagepath = bundle.getString("defaultimagepath");
		defaultimagename = bundle.getString("defaultimagename");
	}
	public static String getDefaultimagepath()
	{
		return defaultimagepath;
	}
	public static String getDefaultimagename()
	{
		return defaultimagename;
	}
}

　　利用common-dbutils.jar和common-dbcp.jar工具来操作数据库：

　　注意查询的时候:

　　QueryRunner qr = new QueryRunner(dataSource);

　　qr.query(sql, new BeanHandler<User>(User.class));查询对象

　　qr.query(sql, new BeanListHandler<User>(User.class));查询对象列表

　　qr.query(sql, new ScalarHandler<>());返回单个值

　　具体可以参考下面代码：

package com.itwang.dao.impl;

import java.sql.SQLException;

import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import com.itwang.dao.InterestNumberDao;
import com.itwang.domain.InterestCard;
import com.itwang.domain.InterestNumber;
import com.itwang.utils.DBCPUtil;

public class InterestNumberDaoImpl implements InterestNumberDao {
	private QueryRunner qr = new QueryRunner(DBCPUtil.getDataSource());
	@Override
	public void save(InterestNumber interestNumber) {
		// TODO Auto-generated method stub
		try {
			qr.update("insert into interestnumber(id,name,follownumber,description,path,filename) values(?,?,?,?,?,?)",interestNumber.getId(),interestNumber.getName(),interestNumber.getFollownumber(),interestNumber.getDescription(),interestNumber.getPath(),interestNumber.getFilename());
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public List<InterestNumber> findAllInterestNumber() {
		// TODO Auto-generated method stub
		List<InterestNumber> list=null;
		try {
			list=qr.query("select * from interestNumber",new BeanListHandler<InterestNumber>(InterestNumber.class));
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return list;
	}
	@Override
	public void deleteInterestNumber(String id) {
		// TODO Auto-generated method stub
		try {
			qr.update("delete from interestnumber where id=?", id);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public InterestNumber findInterestNumberById(String id) {
		// TODO Auto-generated method stub
		InterestNumber interestNumber= null;
		try {
			interestNumber=qr.query("select * from interestnumber where id=?", new BeanHandler<InterestNumber>(InterestNumber.class), id);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return interestNumber;
	}
	@Override
	public void updateInterestNumber(InterestNumber interestNumber) {
		// TODO Auto-generated method stub
		try {
			qr.update("update interestnumber set name=?,follownumber=?,description=?,path=?,filename=? where id=?",interestNumber.getName(),interestNumber.getFollownumber(),interestNumber.getDescription(),interestNumber.getPath(),interestNumber.getFilename(),interestNumber.getId());
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public int checkStatusInterestNumber(String id, String interestnumberid) {
		// TODO Auto-generated method stub
		Long count=null;
		try {
			count=qr.query("select count(*) from interestrelative where uid=? and pid=?",new ScalarHandler<>(), id,interestnumberid);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		if(count.intValue()>0)
			return 1;
		else
			return 0;
	}
	@Override
	public void deleteRelative(String uid, String pid) {
		// TODO Auto-generated method stub
		try {
			qr.update("delete from interestrelative where uid=? and pid=?", uid,pid);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public void addRelative(String id,String uid, String pid) {
		// TODO Auto-generated method stub
		try {
			qr.update("insert into interestrelative(id,uid,pid) values(?,?,?)",id, uid,pid);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public List<InterestNumber> findInterestNumberByKeywords(String searchKeywords) {
		// TODO Auto-generated method stub
		List<InterestNumber> list=null;
		String sqlstring="select * from interestnumber where name like CONCAT('%', ?, '%')";
		try {
			list=qr.query(sqlstring,new BeanListHandler<InterestNumber>(InterestNumber.class),searchKeywords );
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return list;
	}
	@Override
	public void updateFollowNumber(int totalUser,String pid) {
		// TODO Auto-generated method stub
		try {
			qr.update("update interestnumber set follownumber=? where id=?",totalUser,pid);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public int getTotalUserByPid(String pid) {
		// TODO Auto-generated method stub
		Long total=null;
		try {
			total=qr.query("select count(*) from interestrelative where pid=?", new ScalarHandler<>(), pid);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return total.intValue();
	}
	@Override
	public void addInteretCard(InterestCard interestCard) {
		// TODO Auto-generated method stub
		try {
			qr.update("insert into interestcard(id,datetime,title,content,uid,pid) values(?,?,?,?,?,?)",interestCard.getId(),interestCard.getDatetime(),interestCard.getTitle(),interestCard.getContent(),interestCard.getUser().getId(),interestCard.getInterestnumber().getId());
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}