2_demo1.zip

package com.example.demo1; import java.sql.*; public class LjMySQL { Connection conn = null; Statement st = null; ResultSet rs = null; String username = "root"; String password = "123456"; public Connection LjMySQL1(){ try { Class.forName("com.mysql.jdbc.Driver"); String url="jdbc:mysql://localhost:3306/news"; conn= DriverManager.getConnection(url, username, password); st =conn.createStatement(); }catch (Exception e){ } return conn; } public boolean RegUser(String username,String password)throws SQLException{ boolean flag=true; LjMySQL1(); String sql1="select * from userinfo where UName='"+username+"'"; rs=st.executeQuery(sql1); if (rs.next()){ flag=false; }else { String sql= "insert into userinfo(UName,Password) values('"+username+"', '"+password+"')" ; try { st.executeUpdate(sql); }catch (SQLException e){ e.printStackTrace(); } } return flag; } public boolean DeleteDB(String username){ LjMySQL1(); boolean flag=false; String sql5="select * from userinfo where UName='"+username+"'"; try { st.executeQuery(sql5); flag=true; }catch (SQLException e){ e.printStackTrace(); } return flag; } public String FindPassword(String username){ LjMySQL1(); String res = null; String sql3="select Password from userinfo where Uname='"+username+"'"; try { rs=st.executeQuery(sql3); if (rs.next()){ res=rs.getString("Password"); } }catch (SQLException e){ e.printStackTrace(); } return res; } public boolean Yz(String username,String password){ LjMySQL1(); boolean flag=false; String sql4="select * from userinfo where Uname='"+username+"'and Password='"+password+"'"; try { rs = st.executeQuery(sql4); if (rs.next()){ flag=true; }else { flag=false; } }catch (SQLException e){ e.printStackTrace(); } return flag; } public boolean UpdateUser(String username,String password){ LjMySQL1(); boolean flag=false; String sql6="update userinfo set Password='"+password+"'where UName='"+username+"'"; try { st.executeUpdate(sql6); flag=true; }catch (SQLException e){ e.printStackTrace(); } return flag; } public void DisConnect(){ if (conn != null){ try { conn.close(); }catch (SQLException e){ e.printStackTrace(); } } if (st != null){ try { st.close(); }catch (SQLException e){ e.printStackTrace(); } } if (rs != null){ try { rs.close(); }catch (SQLException e){ e.printStackTrace(); } } } }