Response案例

一、验证码生成点击换

public class CodeServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//参数1：宽度   参数2：高度    参数三：字符个数     参数4：干扰线的条数
		//生成图片函数
		ValidateCode vc = new ValidateCode(135, 35, 4, 10);
		//把图片写入到页面中
		vc.write(response.getOutputStream());
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

		<script type="text/javascript">
		function changecode(){
			 document.getElementById("img").src ="/webday10.login/codeServlet?time="+new Date().getTime();
		}
		</script>
		<div id="div1">
		验证码：
		<input type="text" id="inputPassword"  name="checkcode" placeholder="请输入验证码" />
		 <img id="img" src="/webday10.login/codeServlet"    onclick="changecode()"/>
		</div>
	</body>

2、文件下载

public class ServletDemo1 extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	    //response的乱码设
		response.setContentType("text/html;charset=UTF-8");
		//request的post提交乱码设置
		/* request.setCharacterEncoding("UTF-8");*/
		//request的get提交乱码设置
		 //filename = new String(filename.getBytes("iso-8859-1"),"UTF-8");
		 
		 String method = request.getMethod();
		 System.out.println(method);
		   //1、获取请求参数     
		  //获取文件名称
		   String filename = request.getParameter("filename");
		   filename = new String(filename.getBytes("iso-8859-1"),"UTF-8");
		  System.out.println(filename);
		  //获取服务器中的tomcat中的路径
		  ServletContext appliction = this.getServletContext();
		  System.out.println(appliction);
		  //获取当前文件的路径
		  InputStream is = appliction.getResourceAsStream("/WEB-INF/classes/"+filename);
		  //告知浏览器要下载文件的类型
		  response.setHeader("content-disposition","attchment;filename="+filename);
		  //告知浏览器下载文件的类型
		  System.out.println("attchment;filename="+filename);
		  response.setHeader("content-type",appliction.getMimeType(filename));
		  System.out.println(appliction.getMimeType(filename));
		 
		  //响应数据
		  ServletOutputStream os = response.getOutputStream();
		 int len= 0 ;
		 byte[] b= new byte[1024];
		 while((len=is.read(b)) !=-1){
			 os.write(b,0,len);
		 }
		 
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
	doGet(req, resp);
	}

<a href="/webday10/ServletDemo2?filename=1.jpg">下载jpg</a>
		<a href="/webday10/ServletDemo2?filename=2.rar">下载rar</a>
		<a href="/webday10/ServletDemo2?filename=3.zip">下载zip</a>
		<a href="/webday10/ServletDemo2?filename=阿.jpg">下载杨幂</a>