java连接数据库

配置文件 /Stu_PMS/src/config/data.properties 　　DRIVER=com.mysql.jdbc.Driver 　　CONSTR=jdbc:mysql://127.0.0.1:3306/test 　　USERNAME=root 　　PASS=mysql 配置文件驱动 /Stu_PMS/src/com/config/ProMgr.java package JDBC; import java.util.*; public class ProMgr {     static Properties pro = new Properties();             static {                     try{             pro.load(ProMgr.class.getResourceAsStream("data.properties"));//配置文件位于同一个目录下的写法             //配置文件位于不同目录下的写法：pro.load(ProMgr.class.getClassLoader().getResourceAsStream("config/data.properties"));         }catch(Exception e){             e.printStackTrace();         }                 };             public static String getProperty(String key){         return pro.getProperty(key);     }             public static void main(String[] args)     {         System.out.println(getProperty("CONSTR"));     } } 　　 数据库驱动文件 /Stu_PMS/src/com/data/DB.java package JDBC; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DB {     public static Connection getConn(){         Connection conn = null;         String DRIVER = "com.mysql.jdbc.Driver";         String CONSTR = ProMgr.getProperty("CONSTR");         String USERNAME = ProMgr.getProperty("USERNAME");         String PASS = ProMgr.getProperty("PASS");         try {             Class.forName(DRIVER);             conn = DriverManager.getConnection(CONSTR,USERNAME,PASS);         } catch (ClassNotFoundException e) {             e.printStackTrace();         } catch (SQLException e) {             e.printStackTrace();         }          return conn;     }             public static Statement getSta(Connection conn){         Statement st = null;         try {             st = conn.createStatement();         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }         return st;     }             public static ResultSet execQuery(Statement stmt,String sql){         ResultSet rs = null;         try {             rs = stmt.executeQuery(sql);         } catch (SQLException e) {             // TODO Auto-generated catch block             e.printStackTrace();         }         return rs;     }             public static void close(Connection conn){         if(conn!=null){             try {                 conn.close();             } catch (SQLException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }         }     }             public static void close(ResultSet rs){         if(rs!=null){             try {                 rs.close();             } catch (SQLException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }         }     }             public static void close(Statement stmt){         if(stmt!=null){             try {                 stmt.close();             } catch (SQLException e) {                 // TODO Auto-generated catch block                 e.printStackTrace();             }         }     }             public static PreparedStatement getPrestat(Connection conn,String sql){         PreparedStatement pstmt = null;         try {             pstmt = conn.prepareStatement(sql);         } catch (SQLException e) {             e.printStackTrace();         }         return pstmt;     }         } 调用示例 package JDBC; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class Test {     public static void main(String[] args)     {         delete();         //update();         //add();         //query();     }             static void  add()     {         int count;         String sql = "insert into user(name,age) values(?,?)";         Connection conn = DB.getConn();         PreparedStatement pstmt = DB.getPrestat(conn, sql);         try {             pstmt.setString(1, "owen2");             pstmt.setString(2, "21");             count=pstmt.executeUpdate();             System.out.println("影响条数为："+count);                 } catch (SQLException e) {             DB.close(pstmt);             DB.close(conn);             e.printStackTrace();         }finally{             DB.close(pstmt);             DB.close(conn);         }                 }             static void  query()     {         ResultSet rs = null;         String sql = "select * from user where name=? and age=?";         Connection conn = DB.getConn();         PreparedStatement pstmt = DB.getPrestat(conn, sql);         try {             pstmt.setString(1, "刘书");             pstmt.setString(2, "21");             rs = pstmt.executeQuery();             while(rs.next())             {                 System.out.println("name:" + rs.getString("name") + "---age:" + rs.getString("age"));             }         } catch (SQLException e) {             DB.close(rs);             DB.close(pstmt);             DB.close(conn);             e.printStackTrace();         }finally{             DB.close(rs);             DB.close(pstmt);             DB.close(conn);         }                 }             static void  update()     {         int count;         String sql = "update user set name=?,age=? where name=?";         Connection conn = DB.getConn();         PreparedStatement pstmt = DB.getPrestat(conn, sql);         try {             pstmt.setString(1, "owenupdate");             pstmt.setString(2, "22");             pstmt.setString(3, "owen");             count=pstmt.executeUpdate();             System.out.println("影响条数为："+count);                 } catch (SQLException e) {             DB.close(pstmt);             DB.close(conn);             e.printStackTrace();         }finally{             DB.close(pstmt);             DB.close(conn);         }                 }             static void  delete()     {         int count;         String sql = "delete from user where name=?";         Connection conn = DB.getConn();         PreparedStatement pstmt = DB.getPrestat(conn, sql);         try {             pstmt.setString(1, "owen2update");             count=pstmt.executeUpdate();             System.out.println("影响条数为："+count);                 } catch (SQLException e) {             DB.close(pstmt);             DB.close(conn);             e.printStackTrace();         }finally{             DB.close(pstmt);             DB.close(conn);         }                 } }