【JDBC】C3P0连接池的使用

C3P0连接池的c3p0-config.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
	<default-config>
		<property name="driverClass">com.mysql.cj.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql:///jdbctest?serverTimezone=Hongkong</property>
		<property name="user">root</property>
		<property name="password">1234</property>
		<property name="initialPoolSize">5</property>
		<property name="maxPoolSize">20</property>
	</default-config>
</c3p0-config>

工具类

package jdbcUtils;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class JDBCUtils {
	private static final ComboPooledDataSource cpds = new ComboPooledDataSource();
	public static Connection getConection() throws Exception {
		return cpds.getConnection();
	}
	public static void release(Statement stmt, Connection conn) {
		if(stmt != null) {
			try {
				stmt.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
			stmt = null;
		}
		if(conn != null) {
			try {
				conn.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
			conn = null;
		}
	}
	public static void release(ResultSet rs, Statement stmt, Connection conn) {
		if(rs != null) {
			try {
				rs.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
			rs = null;
		}
		if(stmt != null) {
			try {
				stmt.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
			stmt = null;
		}
		if(conn != null) {
			try {
				conn.close();
			}catch(Exception e) {
				e.printStackTrace();
			}
			conn = null;
		}
	}
}

单元测试

package demo1;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import org.junit.Test;
import jdbcUtils.JDBCUtils;
public class JDBCDemo4 {
	@Test
	public void demo4() {
		Connection conn = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try {
			// 获得连接
			conn = JDBCUtils.getConection();
			// 编写SQL
			String sql = "select * from course";
			// 预编译SQL
			pstmt = conn.prepareStatement(sql);
			// 执行SQL
			rs = pstmt.executeQuery();
			while (rs.next()) {
				System.out.println(rs.getInt("id") + " " + rs.getString("name") + " " + rs.getString("category") + " "
						+ rs.getString("desp") + " " + rs.getTimestamp("createTime"));
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.release(rs, pstmt, conn);
		}
	}
}