Java 连接数据库的工具包

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import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;public class DBUtil{  private static final String DBDRIVER="com.mysql.jdbc.Driver";//驱动类类名  private static final String DBNAME="test";//数据库名  private static final String DBURL="jdbc:mysql://localhost:3306/"+DBNAME;//连接URL  private static final String DBUSER="root";//数据库用户名  private static final String DBPASSWORD="root";//数据库密码  private static Connection conn=null;  private static PreparedStatement ps=null;  private static ResultSet rs=null;  //获取数据库连接  public static Connection getConnection(){    try{        Class.forName(DBDRIVER);//注册驱动        conn=DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);//获得连接对象    }catch(ClassNotFoundException e){//捕获驱动类无法找到异常           e.printStackTrace();    }catch(SQLException e){//捕获SQL异常           e.printStackTrace();    }    return conn;  }  //查询数据  public ResultSet select(String sql)throws Exception{    try{        conn=getConnection();        ps=conn.prepareStatement(sql);        rs=ps.executeQuery(sql);    return rs;    }catch(SQLException sqle){        throw new SQLException("select data Exception: "+sqle.getMessage());    }catch(Exception e){        throw new Exception("System error: "+e.getMessage());    }  }  //插入数据  public int insert(String sql)throws Exception{    int num=0;//计数    try{        conn=getConnection();        ps=conn.prepareStatement(sql);        num=ps.executeUpdate();    }catch(SQLException sqle){        throw new SQLException("insert data Exception: "+sqle.getMessage());    }finally{        try{            if(ps!=null){               ps.close();            }        }catch(Exception e){            throw new Exception("ps close exception: "+e.getMessage());        }        try{            if(conn!=null){               conn.close();            }        }catch(Exception e){            throw new Exception("conn close exception: "+e.getMessage());        }    }    return num;  }  //删除数据  public int delete(String sql)throws Exception{    int num=0;//计数    try{        conn=getConnection();        ps=conn.prepareStatement(sql);        num=ps.executeUpdate();    }catch(SQLException sqle){        throw new SQLException("delete data Exception: "+sqle.getMessage());    }finally{        try{            if(ps!=null){                ps.close();            }        }catch(Exception e){            throw new Exception("ps close Exception: "+e.getMessage());        }        try{            if(conn!=null){                conn.close();            }        }catch(Exception e){            throw new Exception("conn close Exception: "+e.getMessage());        }    }    return num;  }  //修改数据  public int update(String sql)throws Exception{    int num=0;//计数    try{        conn=getConnection();        ps=conn.prepareStatement(sql);        num=ps.executeUpdate();    }catch(SQLException sqle){        throw new SQLException("update data Exception: "+sqle.getMessage());    }finally{        try{            if(ps!=null){                ps.close();            }        }catch(Exception e){            throw new Exception("ps close Exception: "+e.getMessage());        }        try{            if(conn!=null){                conn.close();            }        }catch(Exception e){            throw new Exception("conn close Excepiton: "+e.getMessage());        }    }    return num;  }}
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