一、Druid的简单使用
1 try{ 2 //1.创建Druid数据源对象 3 DruidDataSource dataSource = new DruidDataSource(); 4 5 //2.设置数据库连接信息 6 dataSource.setDriverClassName("com.mysql.jdbc.Driver"); 7 dataSource.setUrl("jdbc:mysql://localhost:3306/dbtao?useSSL=false"); 8 dataSource.setUsername("root"); 9 dataSource.setPassword("");10 //设置连接池初始化的连接个数11 dataSource.setInitialSize(5);12 13 //3.从数据库连接池获取数据库连接14 // 首次从连接池获取连接时，会初始化话连接池中的连接数15 Connection conn = dataSource.getConnection();16 PreparedStatement st = conn.prepareStatement("select * from emp");17 ResultSet rs = st.executeQuery();18 while(rs.next()){19 System.out.println(rs.getString("ename"));20 }21 rs.close();22 st.close();23 //4.释放数据库连接，不是关闭数据库连接，而是放回了数据库连接池中24 conn.close();25 //5.关闭数据源26 dataSource.close();27 }catch(Exception e){28 e.getStackTrace();29 } 二、从工厂获取数据源
1 try{ 2 //1.设置数据库连接信息 3 /** Map 构造 4 Map map =new HashMap<>(); 5 map.put("driverClassName", "com.mysql.jdbc.Driver"); 6 map.put("url", "jdbc:mysql://localhost:3306/dbtao?useSSL=false"); 7 map.put("username", "root"); 8 map.put("password", ""); 9 DataSource dataSource = DruidDataSourceFactory.createDataSource(map);10 */11 12 Properties prop = new Properties();13 /**Properties 逐个设置14 prop.setProperty("driverClassName", "com.mysql.jdbc.Driver");15 prop.setProperty("url", "jdbc:mysql://127.0.0.1:3306/00?useSSL=false");16 prop.setProperty("username", "root");17 prop.setProperty("password", "123456");18 */19 20 // 加载 Properties配置文件的内容到对象中21 InputStream in = new FileInputStream("jdbc.properties");22 prop.load(in);23 24 //2.初始化Druid数据源对象25 DataSource dataSource = DruidDataSourceFactory.createDataSource(prop);26 27 Connection conn = dataSource.getConnection();28 PreparedStatement st = conn.prepareStatement("select * from emp");29 ResultSet rs = st.executeQuery();30 while(rs.next()){31 System.out.println(rs.getString("ename"));32 }33 34 rs.close();35 st.close();36 //4.释放数据库连接，不是关闭数据库连接，而是放回了数据库连接池中37 conn.close();38 39 }catch(Exception e){40 e.getStackTrace();41 } 三、封装 DBUtil
1 import java.io.*; 2 import java.sql.*; 3 import java.util.*; 4 import javax.sql.*; 5 import com.alibaba.druid.pool.DruidDataSourceFactory; 6 7 public class DBUtil { 8 static DataSource dataSource; 9 static {10 try {11 Properties prop = new Properties();12 // 1.创建一个字节输入流的对象13 InputStream in = new FileInputStream("jdbc.properties");14 prop.load(in);15 // 2.初始化数据源16 dataSource = DruidDataSourceFactory.createDataSource(prop);17 System.out.println("初始化数据源信息成功....");18 } catch (Exception e) {19 System.out.println("初始化数据源信息异常....");20 e.printStackTrace();21 }22 }23 /**24 * 获取数据库连接池25 */26 public static DataSource getDataSource() {27 return dataSource;28 }29 /**30 * 获取数据库连接31 */32 public static Connection getConnection() {33 Connection conn = null;34 try {35 conn = dataSource.getConnection();36 } catch (SQLException e) {37 e.printStackTrace();38 }39 return conn;40 }41 /**42 * 释放数据库连接43 */44 public static void close(Connection conn,Statement st,ResultSet rs) {45 if(rs!=null) {46 try {47 rs.close();48 } catch (SQLException e) {49 e.printStackTrace();50 }51 }52 close(conn,st);53 }54 public static void close(Connection conn,Statement st) {55 if(st!=null) {56 try {57 st.close();58 } catch (SQLException e) {59 e.printStackTrace();60 }61 }62 close(conn);63 }64 public static void close(Connection conn) {65 if(conn!=null) {66 try {67 conn.close();68 } catch (SQLException e) {69 e.printStackTrace();70 }71 }72 }73 public static void commit(Connection conn){74 if(conn!=null) {75 try {76 conn.commit();77 } catch (SQLException e) {78 e.printStackTrace();79 }80 }81 }82 public static void rollback(Connection conn){83 if(conn!=null) {84 try {85 conn.rollback();86 } catch (SQLException e) {87 e.printStackTrace();88 }89 }90 }91 }
jdbc.properties：
# database configdriverClassName = com.mysql.jdbc.Driverurl = jdbc:mysql://localhost:3306/dbtao?useSSL=falseusername = rootpassword = 123456