目录
遇到的小坑
- 回调函数相对window.onload的摆放位置
- 给回调函数addData传数据时，如何操作才能将数据传进去
代码实现
前端代码
ajax实现关键字联想和自动补全 *{ margin: 0; padding: 0; box-sizing: border-box; } #keyWords{ margin-top: 10px; margin-left: 10px; width: 300px; height: 25px; font-size: 20px; padding-left: 5px; } #dataDiv{ background-color: wheat; width: 300px; margin-left: 10px; display: none; } #dataDiv p{ padding-left: 10px; padding-top: 7px; padding-bottom: 3px; cursor: pointer; } #dataDiv p:hover{ background-color: cornflowerblue; color: white; } window.onload = function (){ //获取dom对象 input_txt = document.getElementById("keyWords") div_data = document.getElementById("dataDiv") //为输入框绑定keyup事件 input_txt.onkeyup = function (){ //输入框为空，隐藏提示层 if(this.value.trim() == ""){ div_data.style.display = "none" }else{ //每当keyup时，发送ajax请求，传递文本框内数据 var xmlHttpRequest = new XMLHttpRequest(); xmlHttpRequest.onreadystatechange = function (){ if(this.readyState == 4){ if(this.status == 200){ //解析后端传来的json数据:[{"content" : "data"}, {}, {}] var jsonArray = JSON.parse(this.responseText) var html = "" for(var i = 0; i < jsonArray.length; i++){ var perData = jsonArray[i].content //为p标签绑定单击事件,将数据以字符串的形式传给回调函数 html += ""+perData+"
" } div_data.innerHTML = html div_data.style.display = "block" }else{ alert("异常状态码: " + this.status) } } } xmlHttpRequest.open("GET", "/ajax/ajaxAutoComplete?keyWords="+this.value+"", true) xmlHttpRequest.send() } } } function addData(perData){ //完成自动补全 input_txt.value= perData //隐藏提示层 div_data.style.display = "none" } <!--java
jsp
service
servlet
docker
linux
-->
后端代码
package com.examples.ajax.servlet;import com.alibaba.fastjson.JSON;import com.examples.ajax.beans.KeyWords;import com.examples.ajax.utils.DBUtils;import jakarta.servlet.ServletException;import jakarta.servlet.annotation.WebServlet;import jakarta.servlet.http.HttpServlet;import jakarta.servlet.http.HttpServletRequest;import jakarta.servlet.http.HttpServletResponse;import java.io.IOException;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;@WebServlet("/ajaxAutoComplete")public class AjaxRequest13 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取前端传来的关键字 String keyWords = request.getParameter("keyWords"); //连接数据库，进行模糊查询 Connection conn = null; PreparedStatement ps = null; ResultSet rs = null; //封装关键字对象 List keyWordsList = new ArrayList(); try { conn = DBUtils.getConnection(); String sql = "select content from tb_search where content like ?"; ps = conn.prepareStatement(sql); ps.setString(1, keyWords + "%"); rs = ps.executeQuery(); while(rs.next()){ String content = rs.getString("content"); //封装成关键字对象 KeyWords keyWordsObj = new KeyWords(content); //将关键字对象封装 keyWordsList.add(keyWordsObj); } } catch (SQLException e) { throw new RuntimeException(e); }finally { DBUtils.close(conn, ps, rs); } //后端数据json化 String jsonKeyWordsArray = JSON.toJSONString(keyWordsList); //返回后端数据 response.getWriter().write(jsonKeyWordsArray); }}用到的实体类
package com.examples.ajax.beans;public class KeyWords { private String content; public KeyWords() { } public KeyWords(String content) { this.content = content; } public String getContent() { return content; } public void setContent(String content) { this.content = content; }}自己封装的jdbc工具类
package com.examples.ajax.utils;import java.sql.*;import java.util.ResourceBundle;/** * 封装自己的jdbc工具类 */public class DBUtils { static ResourceBundle bundle = ResourceBundle.getBundle("jdbc"); static String driver; static String url; static String username; static String password; static { driver = bundle.getString("driver"); url = bundle.getString("url"); username = bundle.getString("username"); password = bundle.getString("password"); try { Class.forName(driver); } catch (ClassNotFoundException e) { throw new RuntimeException(e); } } private DBUtils(){} public static Connection getConnection() throws SQLException { return DriverManager.getConnection(url, username, password); } public static void close(Connection conn, PreparedStatement ps, ResultSet rs){ if(rs != null){ try { rs.close(); } catch (SQLException e) { throw new RuntimeException(e); } } if(ps != null){ try { ps.close(); } catch (SQLException e) { throw new RuntimeException(e); } } if(conn != null){ try { conn.close(); } catch (SQLException e) { throw new RuntimeException(e); } } }}数据库表:
一张表: tb_search
数据表描述: 除了id, 就一个字段 content varchar(255) not null
效果展示:
自己在远程数据库上用docker运行了一个mysql数据库，查询速度比较慢，但演示关键字联想和自动补全功能的测试目的已经达到
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