简单的Java数据库连接和关闭工具类

写JDBC应用的人常常为关闭资源而头痛不已，这些代码枯燥无味，如何才能用简单的代码进行关闭呢，下面我写了一个方法，可以解除你的痛苦：

 

        /** 
         * 关闭所有可关闭资源 
         * 
         * @param objs 可关闭的资源对象有Connection、Statement、ResultSet，别的类型资源自动忽略 
         */ 
        public static void closeAll(Object... objs) { 
                for (Object obj : objs) { 
                        if (obj instanceof Connection) close((Connection) obj); 
                        if (obj instanceof Statement) close((Statement) obj); 
                        if (obj instanceof ResultSet) close((ResultSet) obj); 
                } 
        }

 

这个方法，带了“...”参数，这个实际上是Java5中的可变参数方法。可以不论顺序，不论个数，调用时候直接关闭想要关闭的资源对象就ok了。例如：

 

catch (SQLException e) { 
                        e.printStackTrace(); 
                } finally { 
                        DBTools.closeAll(stmt, pstmt1, pstmt2, conn); 
                }

 

下面给出这个类完整的写法：

package com.lavasoft.ibatistools.common; 

import com.lavasoft.ibatistools.bean.Table; 
import com.lavasoft.ibatistools.metadata.DataSourceMetaData; 
import com.lavasoft.ibatistools.metadata.MySQLDataSourceMetaData; 

import java.io.IOException; 
import java.io.InputStream; 
import java.sql.*; 
import java.util.List; 
import java.util.Properties; 

/** 
* 简单的Java数据库连接和关闭工具类 
* 
* @author leizhimin 11-12-20 下午4:32 
*/ 
public class DBTools { 
        private static String driverClassName, url, user, password; 

        static { 
                init(); 
        } 

        private static void init() { 
                InputStream in = DBTools.class.getResourceAsStream("/com/lavasoft/ibatistools/jdbc.properties"); 
                Properties preps = new Properties(); 
                try { 
                        preps.load(in); 
                        driverClassName = preps.getProperty("jdbc.driver"); 
                        url = preps.getProperty("jdbc.url"); 
                        user = preps.getProperty("jdbc.username"); 
                        password = preps.getProperty("jdbc.password"); 
                } catch (IOException e) { 
                        e.printStackTrace(); 
                } 
        } 

        /** 
         * 创建一个JDBC连接 
         * 
         * @return 一个JDBC连接 
         */ 
        public static Connection makeConnection() { 
                Connection conn = null; 
                try { 
                        Class.forName(driverClassName); 
                        conn = DriverManager.getConnection(url, user, password); 
                } catch (ClassNotFoundException e) { 
                        e.printStackTrace(); 
                } catch (SQLException e) { 
                        e.printStackTrace(); 
                } 
                return conn; 
        } 

        public static void close(Connection conn) { 
                if (conn != null) 
                        try { 
                                conn.close(); 
                        } catch (SQLException e) { 
                                e.printStackTrace(); 
                        } 
        } 

        public static void close(ResultSet rs) { 
                if (rs != null) 
                        try { 
                                rs.close(); 
                        } catch (SQLException e) { 
                                e.printStackTrace(); 
                        } 
        } 

        public static void close(Statement stmt) { 
                if (stmt != null) 
                        try { 
                                stmt.close(); 
                        } catch (SQLException e) { 
                                e.printStackTrace(); 
                        } 
        } 

        /** 
         * 关闭所有可关闭资源 
         * 
         * @param objs 可关闭的资源对象有Connection、Statement、ResultSet，别的类型资源自动忽略 
         */ 
        public static void closeAll(Object... objs) { 
                for (Object obj : objs) { 
                        if (obj instanceof Connection) close((Connection) obj); 
                        if (obj instanceof Statement) close((Statement) obj); 
                        if (obj instanceof ResultSet) close((ResultSet) obj); 
                } 
        } 

        public static void main(String[] args) { 
                DataSourceMetaData dbmd = MySQLDataSourceMetaData.instatnce(); 
                List<Table> tableList = dbmd.getAllTableMetaData(DBTools.makeConnection()); 
                for (Table table : tableList) { 
                        System.out.println(table); 
                } 
        } 
}

 

因为是在写工具，连接用到的次数很少，所以这里采用jdbc模式创建，而没有用到连接池。关闭方法用起来很爽，减少了代码量，也提高了程序的可靠性和质量。

 

本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/746904，如需转载请自行联系原作者