Ajax动态更新页面

2022-07-15 80酷酷网 80kuku.com

　　ajax|动态|页面业务逻辑：动态添加员工信息至列表，列表动态删除员工信息

页面：employeeList.jsp

//创建XMLHttpRequest对象
function createXMLHttpRequest() {
    if (window.ActiveXObject) {
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if (window.XMLHttpRequest) {
        xmlHttp = new XMLHttpRequest();
    }
}

//增加员工
function addEmployee() {
    name = document.getElementById("name").value;
    title = document.getElementById("title").value;
    department = document.getElementById("dept").value;
    action = "add";

    if(name == "" || title == "" || department == "") {
        return;
    }

    var url = "EmployeeListServlet?"
        + createAddQueryString(name, title, department, "add")
        + "&ts=" + new Date().getTime();

    createXMLHttpRequest();
    xmlHttp.onreadystatechange = handleAddStateChange;
    xmlHttp.open("GET", url, true);
    xmlHttp.send(null);
}

//构造参数字串
function createAddQueryString(name, title, department, action) {
    var queryString = "name=" + name
        + "&title=" + title
        + "&department=" + department
        + "&action=" + action;
    return queryString;
}

//回调方法
function handleAddStateChange() {
    if(xmlHttp.readyState == 4) {
        if(xmlHttp.status == 200) {
            updateEmployeeList();
            clearInputBoxes();
        }
        else {
            alert("Error while adding employee.");
        }
    }
}

//清空输入框
function clearInputBoxes() {
    document.getElementById("name").value = "";
    document.getElementById("title").value = "";
    document.getElementById("dept").value = "";
}

//删除员工
function deleteEmployee(id) {
    deleteID = id;

    var url = "EmployeeListServlet?"
        + "action=delete"
        + "&id=" + id
        + "&ts=" + new Date().getTime();

    createXMLHttpRequest();
    xmlHttp.onreadystatechange = handleDeleteStateChange;
    xmlHttp.open("GET", url, true);
    xmlHttp.send(null);
}

//更新员工列表
function updateEmployeeList() {
var responseXML = xmlHttp.responseXML;

    var status = responseXML.getElementsByTagName("status").item(0).firstChild.nodeValue;
    status = parseInt(status);
    if(status != 1) {
        return;
    }

    //创建行
    var row = document.createElement("tr");
    var uniqueID = responseXML.getElementsByTagName("uniqueID")[0].firstChild.nodeValue;
    row.setAttribute("id", EMP_PREFIX + uniqueID);

    //创建列
    row.appendChild(createCellWithText(name));
    row.appendChild(createCellWithText(title));
    row.appendChild(createCellWithText(department));

    //删除按钮
    var deleteButton = document.createElement("input");
    deleteButton.setAttribute("type", "button");
    deleteButton.setAttribute("value", "删除");
    deleteButton.onclick = function () { deleteEmployee(uniqueID); };
    cell = document.createElement("td");
    cell.appendChild(deleteButton);
    row.appendChild(cell);

    document.getElementById("employeeList").appendChild(row);
    updateEmployeeListVisibility();
}

//创建列
function createCellWithText(text) {
    var cell = document.createElement("td");
    cell.appendChild(document.createTextNode(text));
    return cell;
}

//删除行的回调方法
function handleDeleteStateChange() {
    if(xmlHttp.readyState == 4) {
        if(xmlHttp.status == 200) {
            deleteEmployeeFromList();
        }
        else {
            alert("Error while deleting employee.");
        }
    }

}

//删除行
function deleteEmployeeFromList() {
    var status = xmlHttp.responseXML.getElementsByTagName("status").item(0).firstChild.nodeValue;
    status = parseInt(status);
    if(status != 1) {
        return;
    }

    var rowToDelete = document.getElementById(EMP_PREFIX + deleteID);
    var employeeList = document.getElementById("employeeList");
    employeeList.removeChild(rowToDelete);

    //更新列表可视效果
    updateEmployeeListVisibility();
}

//更新列表可视效果
function updateEmployeeListVisibility() {
    var employeeList = document.getElementById("employeeList");
    if(employeeList.childNodes.length > 0) {
        document.getElementById("employeeListSpan").style.display = "";
    }
    else {
        document.getElementById("employeeListSpan").style.display = "none";
    }
}
</script>
</head>

<span id="employeeListSpan" <h2>Employees:</h2>

<table border="1" width="80%">
<tbody id="employeeList"></tbody>
</table>
</span>
</body>
</html>

服务器：EmployeeListServlet.java

package ajaxbook.chap4;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class EmployeeListServlet
extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=GBK";

//Initialize global variables
public void init() throws ServletException {
}

//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
      ServletException, IOException {
    //处理方法参数
    String action = request.getParameter("action");
    if (action.equals("add")){
      addEmployee(request,response);
    }else if (action.equals("delete")){
      deleteEmployee(request,response);
    }
}

//增加员工
protected void addEmployee(HttpServletRequest request,
                             HttpServletResponse response) throws
      ServletException, IOException {
    //得到主键id
    String uniqueID = storeEmployee();

    //创建响应字串
    StringBuffer xml = new StringBuffer("<result><uniqueID>");
    xml.append(uniqueID);
    xml.append("</uniqueID>");
    xml.append("<status>1</status>");
    xml.append("</result>");

//发送
sendResponse(response, xml.toString());
}

//删除员工
protected void deleteEmployee(HttpServletRequest request,
                             HttpServletResponse response) throws
      ServletException, IOException {
    //得到参数id
    String id = request.getParameter("id");

    //创建响应字串
    StringBuffer xml = new StringBuffer("<result>>");
    xml.append("<status>1</status>");
    xml.append("</result>");

//发送
sendResponse(response, xml.toString());
}

//发送响应字串
private void sendResponse(HttpServletResponse response, String responseText)throws IOException {
response.setContentType("text/xml");
response.getWriter().write(responseText);
}

//模拟数据库，得到主键id
private String storeEmployee() {
    String uniqueID = "";
    Random randomizer = new Random(System.currentTimeMillis());
    for (int i = 0; i < 8; i++) {
      uniqueID += randomizer.nextInt(9);
    }

return uniqueID;
}
}

参考：Ajax基础教程作笔记吧