本文目录
- ajax异步请求获取后台数据，java mvc 后台应该如何封装各种实体类数据
- java怎么异步查询用户名是否存在
- 关于Java Ajax 为什么后台有返回值，但是js接收到之后就什么都没有了
- 在java Web中如何用Ajax实现用户名已存在
- ajax {url:url,callback:function(result){.}) 为什么能获取到java中 response.getWriter().print()值
- java中ajax如何获得数据库提取出来的多个数据
- 如何使用ajax调用java类
ajax异步请求获取后台数据，java mvc 后台应该如何封装各种实体类数据
可以使用jsonObject来封装。封装好的格式大概是这样：{"Address":}
java怎么异步查询用户名是否存在
function Check(){$.ajax({ type: "POST", dataType:’json’,url: "xxx.do?params="+$("#d1").val(),cache: false,success: function(result) {if(result.success){ alert("check pass");}else{alert("already exists");}},error: function(request) {}});}
关于Java Ajax 为什么后台有返回值，但是js接收到之后就什么都没有了
你直接在浏览器里输入《你的项目地址》UserServlet?userid=《你的userid值》，看看有没有内容呢
在java Web中如何用Ajax实现用户名已存在
我给你做一个例子：希望能帮到你。实现的功能：注册页面上当输入“lixin”时，显示该用户已被注册。其他的名称无所谓。希望能帮到你。欢迎追问。一个简单的jsp页面：《%@ page language="java" import="java.util.*" pageEncoding="utf-8"%》《%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%》《!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"》《html》 《head》 《base href="《%=basePath%》"》 《title》My JSP ’index.jsp’ starting page《/title》《!--《link rel="stylesheet" type="text/css" href="styles.css"》--》《script type="text/javascript" language="javascript"》//根据浏览器的不同创建不同的XMLHttpRequest function createXmlHttpRequest(){ var xmlreq=false; if(window.XMLHttpRequest){ xmlreq=new XMLHttpRequest(); }else if(window.ActiveXobject){ try{ xmlreq = new ActiveXobject("Msxm12.XMLHTTP"); }catch(e1){ try{ xmlreq = new ActiveXobject("Miscoft.XMLHTTP"); }catch(e2){ } } } return xmlreq; } // function usernameCheck(){ var username = document.all.username.value;//获得text的值 var request = createXmlHttpRequest();//创建request的对象 request.open("post","servlet/ValidationServlet?username="+username); request.send(); request.onreadystatechange = function(){ if(request.readyState==4&request.status==200) { var value = request.responseText; if(value=="true"){ document.all.unc.innerHTML="该用户名已经被注册";} }else{ document.all.unc.innerHTML="该用户可以注册"; }}} 《/script》 《/head》 《body》 用户姓名：《input type ="text" name="username" onblur="usernameCheck()" /》《font color="red" size="-1" id="unc"》《/font》 《br》 用户密码：《input type ="password" name= "userpw" /》 《/body》《/html》用到的Servlet：package sample;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;***隐藏网址******隐藏网址******隐藏网址***public class ValidationServlet extends HttpServlet {/** * The doGet method of the servlet. 《br》 * * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { response.setContentType("text/html");String username = request.getParameter("username");if(username.equals("lixin")){response.getWriter().print("true");}else{response.getWriter().print("false");}}}
ajax {url:url,callback:function(result){.}) 为什么能获取到java中 response.getWriter().print()值
response.getWriter().print()是输出流输出，响应给页面，你通过ajax向服务器发送请求，服务器通过输出流给你响应，ajax中有接收响应的function，自然能够获取到输出流的值。我觉得你应该上网补一补ajax请求和流的知识
java中ajax如何获得数据库提取出来的多个数据
dom下面是一部分程序代码PreparedStatement ps = con.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while(rs.next()){ business = document.createElement("business"); root.appendChild(business); info_id = document.createElement("info_id"); info_id.appendChild(document.createTextNode(rs.getString("info_id"))); business.appendChild(info_id); create_name = document.createElement("create_name"); create_name.appendChild(document.createTextNode(rs.getString("create_name"))); business.appendChild(create_name); create_time = document.createElement("create_time"); create_time.appendChild(document.createTextNode(rs.getString("create_time"))); business.appendChild(create_time); title = document.createElement("title"); title.appendChild(document.createTextNode(rs.getString("title"))); business.appendChild(title); content = document.createElement("content"); content.appendChild(document.createTextNode(rs.getString("content"))); business.appendChild(content); } Element firstPageEL,prePageEL,nextPageEL,lastPageEL; firstPageEL = document.createElement("firstPage"); root.appendChild(firstPageEL); firstPageEL.appendChild(document.createTextNode(firstPage)); prePageEL = document.createElement("prePage"); root.appendChild(prePageEL); prePageEL.appendChild(document.createTextNode(prePage)); nextPageEL = document.createElement("nextPage"); root.appendChild(nextPageEL); nextPageEL.appendChild(document.createTextNode(nextPage)); lastPageEL = document.createElement("lastPage"); root.appendChild(lastPageEL); lastPageEL.appendChild(document.createTextNode(lastPage)); /**Element root = document.createElement("root"); document.appendChild(root); Element title = document.createElement("title"); title.appendChild(document.createTextNode("yaowei")); root.appendChild(title); Element content = document.createElement("content"); content.appendChild(document.createTextNode("yaoweijq")); root.appendChild(content); */ TransformerFactory tf = TransformerFactory.newInstance(); Transformer transformer = tf.newTransformer(); DOMSource source = new DOMSource(document); transformer.setOutputProperty(OutputKeys.ENCODING,"GB2312"); transformer.setOutputProperty(OutputKeys.INDENT,"yes"); StringWriter s = new StringWriter(); StreamResult result1 = new StreamResult(new BufferedWriter(s)); transformer.transform(source,result1); StringBuffer b = s.getBuffer(); con.close(); result = b.toString();WEB端function displayTopic(currPageNum){ send_request("get","private/displayTopic.jsp?currPageNum="+currPageNum,null,"text",listTopic); } function listTopic(){ ***隐藏网址******隐藏网址******隐藏网址***//alert(doc); var xmlDoc = new ActiveXObject("Microsoft.xmldom"); xmlDoc.async = "false"; xmlDoc.loadXML(doc); var content = xmlDoc.getElementsByTagName("topic"); var html = ""; html += "《table frame=box 》"; //alert(html); //alert(html); //alert(content.firstChild.data); for( var i = 0;i《content.length;i++){ html += "《tr》"; html += "《td colspan=2》标题:" + content.firstChild.data + "《/td》《/tr》"; html += "《tr》"; html += "《td》发表人:"+content.firstChild.data + "《/td》"; html += "《td》发表时间:"+content.firstChild.data + "《/td》《/tr》"; html += "《tr》"; html += "《td colspan=2》"+content.firstChild.data + "《/td》《/tr》"; } var firstPage = xmlDoc.getElementsByTagName("firstPage").firstChild.data; var prePage = xmlDoc.getElementsByTagName("prePage").firstChild.data; var nextPage = xmlDoc.getElementsByTagName("nextPage").firstChild.data; var lastPage = xmlDoc.getElementsByTagName("lastPage").firstChild.data; if(firstPage != "false" || prePage != "false" || nextPage != "false" || lastPage != "false"){ html += "《tr》"; html += "《td colspan = 2》"; if(firstPage != "false"){ html += "《input type=\"button\" value=\"首页\" onClick=\"javascript:displayTopic(0)\""; html += "/》"; } if(prePage != "false"){ html += "《input type=\"button\" value=\"前一页\" "; html += "onClick=\"javascript:displayTopic("+prePage+")\"/》"; } if(nextPage != "false"){ html += "《input type=\"button\" value=\"下一页\" "; html += "onClick=\"javascript:displayTopic("+nextPage+")\"/》"; } if(lastPage != "false"){ html += "《input type=\"button\" value=\"尾页\" "; //html += "onClick=\"javascript:displayTopic(\"lastPage\");\" /》"; html += "onClick=displayTopic(\"lastPage\") /》"; } html += "《/td》《/tr》"; } html += "《/table》"; //alert(html); document.getElementById("topicList").innerHTML = ""; document.getElementById("topicList").innerHTML = html; //alert("finish"); }else{ ***隐藏网址***} } }
如何使用ajax调用java类
ajax调用java后台的方法，其实是通过url链接来访问，示例如下：package com.xxxx.xxxx.servlet; import java.io.IOException; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import javax.naming.Context; import javax.naming.InitialContext; import javax.servlet.ServletException; ***隐藏网址******隐藏网址******隐藏网址***import javax.sql.DataSource; public class oaLoginLimitedServlet extends HttpServlet { private static final long serialVersionUID = 1L; private static Connection conn=null; private static PreparedStatement pstmt=null; public oaLoginLimitedServlet() { super(); } public void destroy() { super.destroy(); } public static String getCount(String userid) { String v_sql="....."; String v_count=""; try { pstmt = conn.prepareStatement(v_sql); pstmt.setString(1, userid); ResultSet rs = pstmt.executeQuery(); while(rs.next()){ v_count = rs.getString(1); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { pstmt.close(); conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return v_count; } public static Connection getConnection(){ Context ctx = null; try { ctx = new InitialContext(); DataSource ds = (DataSource)ctx.lookup("jndiname"); conn = ds.getConnection(); } catch (Exception e) { e.printStackTrace(); } return conn; } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String v_userid=request.getParameter("userid"); System.out.println(v_userid); getConnection(); String v_count=getCount(v_userid); response.setCharacterEncoding("UTF-8"); response.getWriter().write(v_count); response.flushBuffer(); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } } 如果要前端能够访问到该servlet，需要将该servlet注册到 web.xml文件中。需要在web.xml文件中添加以下内容 view plaincopy《servlet》 《servlet-name》oaLoginLimitedServlet《/servlet-name》 《servlet-class》com.xxxx.xxxx.servlet.oaLoginLimitedServlet《/servlet-class》 《/servlet》 《servlet-mapping》 《servlet-name》oaLoginLimitedServlet《/servlet-name》 《url-pattern》/oaLoginLimitedServlet《/url-pattern》 《/servlet-mapping》 重启相关服务。通过ajax就可以调用了。 view plaincopyvar msg = $.ajax({ type: "post", url: ....+’/oaLoginLimitedServlet?userid=’+ $(’#act’).val(), async:false }).responseText;***隐藏网址***
