This time I will bring you Servlet3.0 JS for Ajax interaction. What are the precautions for Servlet3.0 JS for Ajax interaction? The following is a practical case, let’s take a look.
Although js.html is a purely static page, the following program must be hung on the Tomcat server to achieve Ajax interaction, otherwise the effect will not be seen.
Eclipse for javaee pay attention to hanging the completed project on Tomcat before running Tomcat.
In addition to the necessary Servlet package for JSP, this project does not need to introduce other things. In fact, I want to directly use a JSP page to complete this project, but nowadays, basically no one who is engaged in JSP writes things directly in the .jsp file, right? All background actions are thrown into .java.
1. Basic goal
Pass the input in the front-end js.html input box to the back-end with the name ajaxRequest and the address/ajaxRequest Servlet.java. The Servlet.java background then returns the corresponding information to the front-end js.html. The js.html does not refresh or jump, and responds immediately.
2. Basic idea
Since it is Servlet3.0, you can use annotations to write Servlets, and you don’t need to write anything in web.xml. Directly let Eclipse generate
and only need to leave the following content in it:
<?xml version="1.0" encoding="UTF-8"?>? <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">? </web-app>
3. Production process
1. First It doesn’t matter whether you write Servlet.java or js.html. Anyway, in Ajax interaction, these two are integrated and cannot be separated.
Look at js.html first. The HTML layout part is very simple. There is not even a form, only two input boxes.
When creating the Ajax object XMLHttpRequest, be careful not to use the XMLHttpRequest keyword as the name of the Ajax object XMLHttpRequest, otherwise some browsers cannot process it.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">?
<html xmlns="http://www.w3.org/1999/xhtml">?
<head>?
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />?
<title>Js</title>?
</head>?
?
<body>?
??<input type="text" id="param1" />?
??<input type="text" id="param2" />?
??<button onclick="ajax()">Go!</button>?
</body>?
</html>?
<script>?
??//創(chuàng)建Ajax對象，不同瀏覽器有不同的創(chuàng)建方法，其實(shí)本函數(shù)就是一個簡單的new語句而已。??
??function?createXMLHttpRequest()?{?
????var?XMLHttpRequest1;?
????if?(window.XMLHttpRequest)?{?
??????XMLHttpRequest1?=?new?XMLHttpRequest();?
????}?else?if?(window.ActiveXObject)?{?
??????try?{?
????????XMLHttpRequest1?=?new?ActiveXObject("Msxml2.XMLHTTP");?
??????}?catch?(e)?{?
????????XMLHttpRequest1?=?new?ActiveXObject("Microsoft.XMLHTTP");?
??????}?
????}?
????return?XMLHttpRequest1;?
??}?
??function?ajax()?{?
????//param1與param2就是用戶在輸入框的兩個參數(shù)?
????var?param1=document.getElementById("param1").value;?
????var?param2=document.getElementById("param2").value;?
????var?XMLHttpRequest1?=?createXMLHttpRequest();?
????//指明相應(yīng)頁面??
????var?url?=?"./ajaxRequest";?
????XMLHttpRequest1.open("POST",?url,?true);?
????//這里沒法解釋，你所有JavaScript的請求頭都這樣寫就對了，不會亂碼??
????XMLHttpRequest1.setRequestHeader("Content-Type",?
????????"application/x-www-form-urlencoded");?
????//對于ajaxRequest，本js.html將會傳遞param1與param2給你。??
????XMLHttpRequest1.send("param1="?+?param1?+?"?m2="?+?param2);?
????//對于返回結(jié)果怎么處理的問題??
????XMLHttpRequest1.onreadystatechange?=?function()?{?
??????//這個4代表已經(jīng)發(fā)送完畢之后??
??????if?(XMLHttpRequest1.readyState?==?4)?{?
????????//200代表正確收到了返回結(jié)果??
????????if?(XMLHttpRequest1.status?==?200)?{?
??????????//彈出返回結(jié)果??
??????????alert(XMLHttpRequest1.responseText);?
????????}?else?{?
??????????//如果不能正常接受結(jié)果，你肯定是斷網(wǎng)，或者我的服務(wù)器關(guān)掉了。??
??????????alert("網(wǎng)絡(luò)連接中斷！");?
????????}?
??????}?
????};?
??}?
</script>
2. Next is Servlet.java. In fact, both doGet and doPost print things on the page, but they take this different form. PrintStream is the output stream of the previous JDK, and PrintWriter seems to be the output stream after JDK1.4. But this part is too simple. Input and output streams are all required courses in Java, right?
js.html After passing param1 and param2 to this Servlet.java, wait for this Servlet.java to print out the corresponding things, and then read them directly through the XMLHttpRequest1.responseText variable in the front desk.
package?jsServletAjax;?
import?java.io.*;??
import?javax.servlet.*;??
import?javax.servlet.http.*;??
import?javax.servlet.annotation.*;??
??
//說明這個Servlet是沒有序列號的??
@SuppressWarnings("serial")??
//說明這個Servlet的名稱是ajaxRequest，其地址是/ajaxRequest?
//這與在web.xml中設(shè)置是一樣的??
@WebServlet(name?=?"ajaxRequest",?urlPatterns?=?{?"/ajaxRequest"?})??
public?class?Servlet?extends?HttpServlet?{??
??//放置用戶之間通過直接在瀏覽器輸入地址訪問這個servlet??
??protected?void?doGet(HttpServletRequest?request,??
??????HttpServletResponse?response)?throws?ServletException,?IOException?{??
????PrintStream?out?=?new?PrintStream(response.getOutputStream());??
????response.setContentType("text/html;charSet=utf-8");??
????out.print("請正常打開此頁");?
??}??
??
??protected?void?doPost(HttpServletRequest?request,??
??????HttpServletResponse?response)?throws?ServletException,?IOException?{?
????response.setContentType("text/html;?charset=utf-8");?
????PrintWriter?pw?=?response.getWriter();?
????request.setCharacterEncoding("utf-8");?
????String?param1=request.getParameter("param1");?
????String?param2=request.getParameter("param2");?????
????pw.print("前臺傳來了參數(shù)：param1="+param1+"，param2="+param2);?
????pw.flush();?
????pw.close();?
??}??
}
I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!
Recommended reading:
Use vue to implement tree menu bar function
preload() function and image upload usage
The above is the detailed content of Servlet3.0+JS for Ajax interaction. For more information, please follow other related articles on the PHP Chinese website!
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