usercheck.java

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package DB;

import bean.ConnectionBean;
import java.sql.ResultSet;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.ArrayList;
import java.sql.Statement;

public class UserCheck {
    public UserCheck() {
    }

//判断用户名是否正确
    public String Usercheck(String username, String pwd) {
        ConnectionBean dbcon = new ConnectionBean();
        String rest = null;
        Connection con = null;
        ResultSet ret = null;
        Statement st = null;

        try {

            con = dbcon.getConnection();
            st = con.createStatement();
            ret = st.executeQuery("select password from admin where Username='" +
                                  username + "'");

            if (ret.next()) {
                if (pwd.equals(ret.getString(1))) {
                    rest = "OK"; //如果正确返回OK
                } else {
                    rest = "pwd";
                }
            } else {
                rest = "NOUSER"; //如果用户名不正确即为用户名不存在
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                //关闭所有连接
                if (ret != null) {
                    ret.close();
                }
                if (con != null) {
                    con.close();
                }
            } catch (SQLException se) {
                se.printStackTrace();
            }
        }
        return rest;
    }
}