前端显示server端的数据
来源：互联网 发布：ubuntu libxml 编辑：程序博客网 时间：2024/05/24 07:11
在使用ajax的时候，server端处理完相关的逻辑之后，根据操作完的结果，需要给前端展现不同的提示，这种提示可以在前端展示也可以在后端操作，这里我就说说在后端如何给前端发送数据的
1、前端发送相应的ajax请求
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title><script type="text/javascript" src="../js/jquery-1.4.4.js"></script></head><script type="text/javascript">function test(){var date = new Date();timestamp = date.getTime();//alert(timestamp.getTime());//参数后面加上时间戳是以为ajax机制利用了缓存，如果参数一致就不会再次发送请求了//前面的../表示路径要在上一个目录，才能发送请求$.get("../AjaxWrite", { name: "John", time: "2pm",timestamp:timestamp},//function方法是接受server端传递过来的方法function(data){alert(data);});}</script><body><button onclick="test()">test</button><form action="../AjaxWrite"><input type="submit" value="submit"/></form></body></html>
2、server端向前端写数据
package hb.com.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class AjaxWrite extends HttpServlet {private static final long serialVersionUID = 1L; public AjaxWrite() { super(); }protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("1");System.out.println(request.getParameter("name"));System.out.println(request.getParameter("time"));PrintWriter pw = response.getWriter();pw.write("huangbiao");//server端向前端发送的数据一定 要flush()方法才能被前端接受pw.flush();pw.close();//关闭数据流}}
3、前端就会显示server端写的数据"huangbiao"弹出
利用JSP页面或者是HTML页面下载文件的原理
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title><script type="text/javascript" src="../js/jquery-1.4.4.js"></script></head><script type="text/javascript">function test(){var date = new Date();var timestamp = date.getTime();alert(timestamp);$.get("../FileDownload",{"timestamp":timestamp},function(data){alert(data);});}</script><body><button onclick="test()">test</button><form action="../FileDownload"><input type="submit" value="submit"/></form></body></html>
前端触发请求，server端向前端写数据
package hb.com.servlet;import java.io.BufferedInputStream;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class FileDownload extends HttpServlet {private static final long serialVersionUID = 1L; public FileDownload() { super(); }protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//写明要下载的文件的大小int fileLength = 0;File file = new File("c:\\aaa.xml");FileInputStream fis = new FileInputStream(file);fileLength = fis.available();BufferedInputStream buff = new BufferedInputStream(fis);response.setContentLength(fileLength);response.setContentType("application/x-msdownload");response.setHeader("Content-disposition", "attachment;filename=" + "黄彪.xml");byte[] b = new byte[1024];// 相当于我们的缓存long k = 0;// 该值用于计算当前实际下载了多少字节// 从response对象中得到输出流,准备下载OutputStream myout = response.getOutputStream(); // 开始循环下载while (k < fileLength) {int j = buff.read(b, 0, 1024);k += j;// 将b中的数据写到客户端的内存myout.write(b, 0, j);}// 将写入到客户端的内存的数据,刷新到磁盘myout.flush();myout.close();//关闭数据流}}
总结：实际上下载问价也是属于server端向前端写数据，只是以文件的方式展现出来，并保存到磁盘上了
