jdbc及C3P0连接数据库的方法

一、jdbc连接数据库

jdbcUtil:

public class JdbcUtil {

	private static String url = "jdbc:oracle:thin:@127.0.0.1:15211:orcl";
	private static String user = "root";
	private static String password = "root";
	private static String driver = "oracle.jdbc.OracleDriver";
	// 连接数据库
	public static Connection getConnection() {
		Connection con = null;
		try {
			// 初始化驱动
			Class.forName(driver);
			// 获取数据库连接
			con = DriverManager.getConnection(url, user, password);
			System.out.println("数据库初始化成功！");
		} catch (Exception e) {
			System.out.println("数据库初始化失败!");
		}

		return con;
	}

	// 关闭数据库连接
	public static void conClose(Connection con, PreparedStatement st,
			ResultSet rs) {

		try {
			if (con != null) {
				con.close();
			}
			if (st != null) {
				con.close();
			}
			if (rs != null) {
				con.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}

	}

}

基于jdbc的crud:

	// 保存
	public static boolean save(User user) {
		Connection con = JdbcUtil.getConnection();
		String sql = "insert into Tuser(id,username,password) values(?,?,?)";
		PreparedStatement ps = null;
		int n = 0;
		try {
			ps = con.prepareStatement(sql);
			ps.setInt(1, user.getId());
			ps.setString(2, user.getUsername());
			ps.setString(3, user.getPassword());
			n = ps.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JdbcUtil.conClose(con, ps, null);
		}
		if (n > 0) {
			return true;
		}

		return false;

	}

	// 查询
	public static User query(String name) {
		Connection con = JdbcUtil.getConnection();
		String sql = "select * from Tuser where username=?";
		PreparedStatement ps = null;
		ResultSet rs = null;// 定义一个结果集
		User user = null;
		try {
			ps = con.prepareStatement(sql);
			ps.setString(1, name);
			rs = ps.executeQuery();
			while (rs.next()) {
				user = new User();
				user.setId(rs.getInt(1));
				user.setUsername(rs.getString(2));
				user.setPassword(rs.getString(3));
			}

		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JdbcUtil.conClose(con, ps, rs);
		}
		return user;

	}

二、c3p0连接数据库

配置文件dataSource.properties：

c3p0.driverClass=oracle.jdbc.OracleDriver
c3p0.jdbcUrl=jdbc:oracle:thin:@127.0.0.0:15211:orcl
c3p0.user=root
c3p0.password=root
c3p0.minPoolSize=0
c3p0.maxPoolSize=10
#连接的最大空闲时间,如果超过这个时间，连接还没被使用，则会断开
c3p0.maxIdleTime=60
#连接池无空闲连接时一次性创建新连接的个数
c3p0.acquireIncrement=2
#连接池为数据源缓存的PreparedStatement总数。为0不缓存
c3p0.maxStatements=0
#连接池获得新连接失败时重试额次数
c3p0.acquireRetryAttempts=30
DataBaseName=Oracle

当然也可以配置在xml里，这里就配在properties文件里了。

工具类：

import java.beans.PropertyVetoException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import org.springframework.jdbc.core.JdbcTemplate;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public class c3p0Util {

	protected static ComboPooledDataSource ds = new ComboPooledDataSource(true);
	protected static JdbcTemplate jdbcTemplate;

	static {
		try {
			initDBInFo();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * @throws IOException
	 * @throws PropertyVetoException
	 * @Title: initDBInFo
	 * @Description: 初始化数据库连接池
	 */
	private static void initDBInFo() throws IOException, PropertyVetoException {
		Properties pro = new Properties();
		InputStream in = Thread.currentThread().getContextClassLoader()
				.getResourceAsStream("dataSource.properties");
		pro.load(in);
		try {
			 ds.setDriverClass(pro.getProperty("c3p0.driverClass"));
			 ds.setJdbcUrl(pro.getProperty("c3p0.jdbcUrl"));
			 ds.setUser(pro.getProperty("c3p0.user"));
			 ds.setPassword(pro.getProperty("c3p0.password"));
			 ds.setMinPoolSize(Integer.valueOf(pro.getProperty("c3p0.minPoolSize")));
			 ds.setMaxPoolSize(Integer.valueOf(pro.getProperty("c3p0.maxPoolSize")));
			 ds.setMaxIdleTime(Integer.valueOf(pro.getProperty("c3p0.maxIdleTime")));
			 ds.setAcquireIncrement(Integer.valueOf(pro.getProperty("c3p0.acquireIncrement")));
			 ds.setMaxStatements(Integer.valueOf(pro.getProperty("c3p0.maxStatements")));
			 ds.setIdleConnectionTestPeriod(Integer.valueOf(pro.getProperty("c3p0.idleConnectionTestPeriod")));
			 ds.setAcquireRetryAttempts(Integer.valueOf(pro.getProperty("c3p0.acquireRetryAttempts")));
			jdbcTemplate = new JdbcTemplate(ds);

		} catch (NumberFormatException e) {
			System.out.println("数据库连接池初始化失败：" + e);
			e.printStackTrace();
		}
	}

	
}

这里用到了spring的JdbcTemplate,需要自己下载jar包哦。

测试类：

String sql = "select * from Tuser";
		try {
			List<Map<String, Object>> list = jdbcTemplate.queryForList(sql);
			System.out.println(list);
		} catch (Exception e) {
			e.printStackTrace();
		}

大功告成！