Java之数据库连接（一）

Java之数据库连接基础

     代码片段总结了Java与数据库连接的基本方法，连接SQL、MySql等只需修改相应的数据库类型和端口号，其余步骤同。数据库的基本操作包括：增、删、改、查，一应方法都有定义，需要时只需要调用相应的方法即可。

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package cn.JJ;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ParameterMetaData;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;/** * 查询结果处理接口 */interface ResultSetHander {Object hander(ResultSet rs);}/** * 类说明：数据库连接和释放 */public class JDBCUtils {private static String driver = "com.mysql.jdbc.Driver";private static String url = "jdbc:mysql://localhost:3306/chat";private static String user = "root";private static String password = "root";private static Connection con = null;// 注册驱动static {try {Class.forName(driver);} catch (ClassNotFoundException e) {e.printStackTrace();}}// 创建连接public static Connection getConnection() {if (con == null) {try {con = DriverManager.getConnection(url, user, password);} catch (SQLException e) {throw new RuntimeException(e);}}return con;}// 关闭连接public static void colse(ResultSet rs, Statement st, Connection con) {if (rs != null) {try {rs.close();} catch (SQLException e) {throw new RuntimeException(e);}}if (st != null) {try {st.close();} catch (SQLException e) {throw new RuntimeException(e);}}if (con != null) {try {con.close();} catch (SQLException e) {throw new RuntimeException(e);}}}// 更新数据库public static void update(String sql, Object[] params) {Connection con = JDBCUtils.getConnection();Statement stmt = null;ResultSet rs = null;try {PreparedStatement ps = con.prepareStatement(sql);ParameterMetaData psm = ps.getParameterMetaData();// 获得查询语句的元数据信息int paramNum = psm.getParameterCount();// 得到参数的总个数for (int i = 1; i <= paramNum; i++) {ps.setObject(i, params[i - 1]);}ps.executeUpdate();} catch (SQLException e) {throw new RuntimeException(e);} finally {JDBCUtils.colse(rs, stmt, con);}}// 查询数据库public static Object query(String sql, Object[] params, ResultSetHander rsh) {Connection con = JDBCUtils.getConnection();Statement stmt = null;ResultSet rs = null;try {PreparedStatement ps = con.prepareStatement(sql);ParameterMetaData psm = ps.getParameterMetaData();// 获得查询语句的元数据信息int paramNum = psm.getParameterCount();// 得到参数的总个数for (int i = 1; i <= paramNum; i++) {ps.setObject(i, params[i - 1]);}rs = ps.executeQuery();return rsh.hander(rs);} catch (SQLException e) {throw new RuntimeException(e);} finally {JDBCUtils.colse(rs, stmt, con);}}}