【Servlet3.0】
Servlet3.0 与 Servlet2.5：
* Servlet3.0需要运行在tomcat7以上的服务器中.
* Servlet3.0以后web.xml就不是必须的.
1.Servlet3.0支持注解开发.
2.提供异步请求.
3.支持文件上传.
【Servlet3.0支持注解开发】
使用@WebServlet替换web.xml中配置的Servlet：
@WebServlet(urlPatterns="/ServletDemo1",loadOnStartup=2,initParams=@WebInitParam(name="username",value="root"))
使用@WebListener替换web.xml中监听器的配置：
@WebListener
使用@WebFilter替换web.xml中的过滤器的配置:
@WebFilter(urlPatterns="/*")
【Servlet3.0支持异步请求-了解】
使用的是多线程的方式处理的,将传统的方式一次请求的非常耗时的操作,分成多个线程去处理.
需要在Servlet上添加一个属性:
@WebServlet(urlPatterns="/ServletDemo2",asyncSupported=true)
@WebServlet(urlPatterns="/ServletDemo2",asyncSupported=true)
public class ServletDemo2 extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
AsyncContext context = req.startAsync(req, resp);
context.start(new MyRunner(context));
for(int i=1;i<=20;i++){
System.out.println(i);
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
class MyRunner implements Runnable{
private AsyncContext context;
public MyRunner(AsyncContext context) {
this.context = context;
}
@Override
public void run() {
for(char i='a';i<='z';i++){
try {
context.getResponse().getWriter().println(i);
Thread.sleep(100);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
Ø 文件上传：
文件上传：指的是将本地的文件 写到 服务器上.
Ø 文件上传的要素：
1.表单的提交的方式必须是POST.
2.表单中必须有一个文件上传项:<input type=”file”>,而且文件上传项必须有name属性和值.
* <input type=”file” name=”upload”/>
3.表单的enctype属性的值必须是multipart/form-data
Ø 文件上传的抓包分析：
未修改enctype属性的时候:
POST /WEB17_WEB/demo1/demo1.jsp HTTP/1.1
Accept: text/html, application/xhtml+xml, */*
X-HttpWatch-RID: 22325-10011
Referer: http://localhost:8080/WEB17_WEB/demo1/demo1.jsp
Accept-Language: zh-Hans-CN,zh-Hans;q=0.5
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
Host: localhost:8080
Content-Length: 47
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: JSESSIONID=99CD51DA9A47D29200168968AD983E9E
upload=C%3A%5CUsers%5Capple%5CDesktop%5Caaa.txt
已经修改了enctype属性:
POST /WEB17_WEB/demo1/demo1.jsp HTTP/1.1
Accept: text/html, application/xhtml+xml, */*
X-HttpWatch-RID: 22325-10026
Referer: http://localhost:8080/WEB17_WEB/demo1/demo1.jsp
Accept-Language: zh-Hans-CN,zh-Hans;q=0.5
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko
Content-Type: multipart/form-data; boundary=---------------------------7e02e526160b66
Accept-Encoding: gzip, deflate
Host: localhost:8080
Content-Length: 224
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: JSESSIONID=99CD51DA9A47D29200168968AD983E9E
-----------------------------7e02e526160b66
Content-Disposition: form-data; name="upload"; filename="C:\Users\apple\Desktop\aaa.txt"
Content-Type: text/plain
Hello shouyi
-----------------------------7e02e526160b66—
package com.itheima.servlet;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
/**
* 文件上传的Servlet
*/
@WebServlet("/UploadServlet")
@MultipartConfig
public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 接收普通项:
request.setCharacterEncoding("UTF-8");
String desc = request.getParameter("desc");
System.out.println("文件描述:"+desc);
Part part = request.getPart("upload");
// 获得上传的文件的大小
long size = part.getSize();
System.out.println("文件大小"+size);
String type = part.getContentType();
System.out.println("文件类型"+type); // text/plain image/jpeg
String name = part.getName();
System.out.println(name);
// 获得文件名：
String header = part.getHeader("Content-Disposition");
System.out.println(header);
int idx = header.lastIndexOf("filename=\"");
String fileName = header.substring(idx+10, header.length()-1);
System.out.println(fileName);
// 获得文件内容:
InputStream is = part.getInputStream();
// 获得文件上传路径：
String path = this.getServletContext().getRealPath("/upload");
OutputStream os = new FileOutputStream(path+"/"+fileName);
int len = 0;
byte[] b = new byte[1024];
while((len = is.read(b))!=-1){
os.write(b, 0, len);
}
is.close();
os.close();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
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