java连接数据库的代码

1.连接MySQL数据库

package mysql;  import java.sql.*;  /**  * @author xys  */ public class ConnectMysql {     public static Connection getConnection() throws ClassNotFoundException, SQLException {         String url = "jdbc:mysql://localhost:3306/databaseName";         String user = "mysqluser";         String password = "password";         String driverClass = "com.mysql.cj.jdbc.Driver";         Connection connection = null;         Class.forName(driverClass);         try {             connection = DriverManager.getConnection(url, user, password);         } catch (SQLException e) {             e.printStackTrace();         }         if (connection != null) {             System.out.println("数据库连接成功");         } else {             System.out.println("数据库连接失败");             connection.close();         }         return connection;     }      public void getResult() throws ClassNotFoundException, SQLException {         // 实例化 Statement 对象         Statement statement = getConnection().createStatement();         // 要执行的 Mysql 数据库操作语句（增、删、改、查）         String sql = "";         // 展开结果集数据库         ResultSet resultSet = statement.executeQuery(sql);         while (resultSet.next()) {             // 通过字段检索             int id = resultSet.getInt("id");             String name = resultSet.getString("name");              // 输出数据             System.out.println("ID : " +id);             System.out.println("name :" + name);         }         // 完成后需要依次关闭         resultSet.close();         statement.close();         getConnection().close();     } }

2.连接Oracle数据库

package cn.zhisheng.test.jdbc;  import oracle.jdbc.driver.OracleDriver; import java.sql.*; import java.util.Properties; /**  * Created by 10412 on 2016/12/27.  * JDBC的六大步骤  * JAVA连接Oracle的三种方式  */ public class JdbcTest {     public static void main(String[] args) {         Connection connect = null;         Statement statement = null;         ResultSet resultSet = null;          try {             //第一步：注册驱动             //第一种方式：类加载(常用)             //Class.forName("oracle.jdbc.OracleDriver");              //第二种方式：利用Driver对象             Driver driver = new OracleDriver();             DriverManager.deregisterDriver(driver);               //第二步：获取连接             //第一种方式：利用DriverManager（常用）             //connect = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE", "你的oracle数据库用户名", "用户名密码");              //第二种方式：直接使用Driver             Properties pro = new Properties();             pro.put("user", "你的oracle数据库用户名");             pro.put("password", "用户名密码");             connect = driver.connect("jdbc:oracle:thin:@localhost:1521:XE", pro);              //测试connect正确与否             System.out.println(connect);                 //第三步：获取执行sql语句对象             //第一种方式:statement             //statement = connect.createStatement();              //第二种方式：PreStatement             PreparedStatement preState = connect.prepareStatement("select  * from tb1_dept where id = ?");               //第四步：执行sql语句             //第一种方式：             //resultSet = statement.executeQuery("select  * from tb1_dept");              //第二种方式：             preState.setInt(1, 2);//1是指sql语句中第一个？,  2是指第一个？的values值             //resultSet = preState.executeQuery();        //执行查询语句             //查询任何语句，如果有结果集，返回true，没有的话返回false,注意如果是插入一条数据的话，虽然是没有结果集，返回false，但是却能成功的插入一条数据             boolean execute = preState.execute();             System.out.println(execute);              //第五步：处理结果集             while (resultSet.next())             {                 int id = resultSet.getInt("id");                 String name = resultSet.getString("name");                 String city = resultSet.getString("city");                 System.out.println(id+"   "+name+"   "+city);  //打印输出结果集             }         } catch (Exception e) {             e.printStackTrace();         }finally {             //第六步：关闭资源                 try {                     if (resultSet!=null) resultSet.close();                     if (statement!=null) statement.close();                     if (connect!=null) connect.close();                 } catch (SQLException e) {                     e.printStackTrace();                 }         }     } }

3.连接SqlServer数据库

 package com.connDBTest;  import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException;  public class GetConnectionSqlServer {     public void getConnectionSqlServer() {          String driverName = "com.microsoft.jdbc.sqlserver.SQLServerDriver";         String dbURL = "jdbc:sqlserver://localhost:1433;databasename=USCSecondhandMarketDB"; // 1433是端口，"USCSecondhandMarketDB"是数据库名称         String userName = "sa"; // 用户名         String userPwd = "sa"; // 密码          Connection dbConn = null;         try {              Class.forName(driverName).newInstance();         } catch (Exception ex) {             System.out.println("驱动加载失败");             ex.printStackTrace();         }         try {             dbConn = DriverManager.getConnection(dbURL, userName, userPwd);             System.out.println("成功连接数据库！");         } catch (Exception e) {             e.printStackTrace();         } finally {              try {                 if (dbConn != null)                     dbConn.close();             } catch (SQLException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }         }     }      public static void main(String[] args) {         GetConnectionSqlServer getConn = new GetConnectionSqlServer();         getConn.getConnectionSqlServer();      } }