Java JDBC连接数据库常见操作总结

 # db.properties jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=UTF-8 jdbc.username=root jdbc.password=123456 # paramter for BasicDataSource initSize=2 maxActive=2 

 # db.properties jdbc.driver=oracle.jdbc.OracleDriver jdbc.url=jdbc:oracle:thin:localhost:1521:orcl jdbc.username=root jdbc.password=123456 # paramter for BasicDataSource initSize=2 maxActive=2 

 package JDBC; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties; /** * JDBC连接数据库管理工具类 */ public class JDBC { static String driver; static String url; static String username; static String password; static { try { Properties cfg = new Properties(); InputStream in = JDBC.class.getClassLoader().getResourceAsStream("db.properties"); cfg.load(in);  //将文件内容加载到Properties对象中(以散列表形式存在) driver = cfg.getProperty("jdbc.driver"); url = cfg.getProperty("jdbc.url"); username = cfg.getProperty("jdbc.username"); password = cfg.getProperty("jdbc.password"); in.close(); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException(e); } } /** * 创建数据库连接 */ public static Connection getConnection() { try { Class.forName(driver); //注册驱动 Connection conn = DriverManager.getConnection(url, username, password); return conn; } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } } /* * 关闭数据库的连接 */ public static void close(Connection conn) { if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } 

 package JDBC; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.SQLException; import java.util.Properties; import org.apache.commons.dbcp.BasicDataSource; /** * 连接池版本的数据库连接管理工具类 */ public class DBUtils { private static String driver; private static String url; private static String username; private static String password; private static int initSize; private static int maxActive; private static BasicDataSource dbs; static { dbs = new BasicDataSource(); Properties cfg = new Properties(); try { InputStream in = DBUtils.class.getClassLoader().getResourceAsStream("db.properties"); cfg.load(in); // 初始化参数 driver = cfg.getProperty("jdbc.driver"); url = cfg.getProperty("jdbc.url"); username = cfg.getProperty("jdbc.username"); password = cfg.getProperty("jdbc.password"); initSize = Integer.parseInt(cfg.getProperty("initSize")); maxActive = Integer.parseInt(cfg.getProperty("maxActive")); in.close(); // 初始化连接池 dbs.setDriverClassName(driver); dbs.setUrl(url); dbs.setUsername(username); dbs.setPassword(password); dbs.setInitialSize(initSize); dbs.setMaxActive(maxActive); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException(e); } } /** * 创建数据库连接,从连接池中获取连接,如果连接池满了,则等待. */ public static Connection getConnection() { try { Connection conn = dbs.getConnection(); return conn; } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } } /* * 关闭数据库的连接,归还到连接池 */ public static void close(Connection conn) { if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } //回滚，仅在禁用自动提交时使用 public static void rollback(Connection conn) { if (conn != null) { try { conn.rollback(); } catch (SQLException e) { e.printStackTrace(); } } } } 

 Connection conn=null; try{ conn=DbUtils.getConnection(); Statement st=conn.createStatement(); String sql="select id, name from people"; ResultSet rs=st.executeQuery(sql); while(rs.next()){ int id=rs.getInt("id"); String name=rs.getString("name"); System.out.println(id+","+name); } //结果集元数据 ResultSetMetaData meta = rs.getMetaData(); int n = meta.getColumnCount(); //多少列 for(int i=1; i<=n; i++){ String name= meta.getColumnName(i); //获取列名 System.out.println(name); } rs.close();//释放查询结果 st.close();//释放语句对象 }catch(Exception e){ e.printStackTrace(); }finally { DbUtils.close(conn); } 

 try { conn = DBUtils.getConnection(); conn.setAutoCommit(false);  //取消自动提交, 后续手动提交 String sql="update people set name=? where id=? "; PreparedStatement ps= conn.prepareStatement(sql); //按照顺序发送参数 ps.setString(1, "Lao Wang"); ps.setInt(2, 100); //执行"执行计划" int n=ps.executeUpdate(); conn.commit();  //手动提交 } catch (Exception e) { e.printStackTrace(); DBUtils.rollback(conn); //异常回滚 }finally{ DBUtils.close(conn); } 

 Statement st=conn.createStatement(); st.addBatch(sql1); //sql1 添加到Statement的缓存中 st.addBatch(sql2); st.addBatch(sql3); int[] ary=st.executeBatch();  //执行一批SQL 

 PreparedStatement ps = conn.prepareStatement(sql); ps.setInt(1, 1); ps.setString(2, "wang"); ps.addBatch();   //将参数添加到ps缓存区 ps.setInt(1, 2); ps.setString(2, "li"); ps.addBatch();   //将参数添加到ps缓存区 int[] ary = ps.executeBatch(); // 批量执行