摘要：需求通過異步刷新頁面驗證用戶輸入的賬號密碼是否在數(shù)據(jù)庫中存在。下面是下查詢的代碼查詢用戶名是否存在語句連接代碼關(guān)于類關(guān)于控制層獲取到輸入的用戶名調(diào)用中的查詢方法設(shè)置字符編碼關(guān)閉資源

通過ajax異步刷新頁面驗證用戶輸入的賬號密碼是否在數(shù)據(jù)庫中存在。

JSP+Servlet+Oracle

JSP部分：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>








    請輸入用戶名：
    

這里沒有用Dao層，直接用servlet和service層進行驗證。
下面是service下JDBC查詢的代碼：

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import com.stx.service.User;
import com.stx.service.ConnectionManager;

public class ajaxService {
    public boolean  searchUser (String uname) {
    //jdbc查詢用戶名是否存在
        boolean isFalse = false;
        Connection connection = null;
        Statement stmt = null;
        ResultSet rs = null;
        connection = ConnectionManager.getConnection();
        try {
            stmt = connection.createStatement();
            String sql = "select * from user_b where uname=""+uname+""";//sql語句
            rs = stmt.executeQuery(sql);
            isFalse=rs.next();

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            ConnectionManager.closeResultSet(rs);
            ConnectionManager.closeStatement(stmt);
            ConnectionManager.closeConnection(connection);
        }
        return isFalse;
    }
}

JDBC連接代碼：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


public class ConnectionManager {
    private final static String DRIVER_CLASS = "oracle.jdbc.OracleDriver";
    private final static String URL = "jdbc:oracle:thin:@localhost:1521:orcl";
    private final static String DBNAME = "ibook";
    private final static String PASSWORD = "qwer";

    public static Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName(DRIVER_CLASS);
            connection = DriverManager.getConnection(URL, DBNAME, PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }

    public static void closeResultSet(ResultSet rs) {
        try {
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void closeConnection(Connection connection) {
        try {
            if (connection != null && !connection.isClosed())
                connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void closeStatement(Statement stmt) {
        try {
            if (stmt != null)
                stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

關(guān)于user類：

 public class User {
        private String uname;
        public User() {
            super();
        }
        public User(String uname) {
            super();
            this.uname = uname;
    
        }
    
        public String getUname() {
            return uname;
        }
        public void setUname(String uname) {
            this.uname = uname;
        }

關(guān)于控制層servlet：

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.stx.service.ajaxService;

/**
 * Servlet implementation class loginServlet
 */
public class loginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private ajaxService ajaxService = new ajaxService();

    /**
     * @see HttpServlet#HttpServlet()
     */
    public loginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");//獲取到輸入的用戶名
        boolean isUname = ajaxService.searchUser(uname);//調(diào)用service中的查詢方法
        response.setCharacterEncoding("UTF-8");//設(shè)置字符編碼
        PrintWriter out = response.getWriter();
        out.print(isUname);
        out.flush();
        out.close();//關(guān)閉資源
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}