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1.@WebListener注解
表示的就是我们之前的在xml中配置的
<listener>
<listener-class>ListenerClass</listener-class>
</listener>
下面我们只需要在我们写好的Listener类上面加上这个@WebListener注解就OK啦
使用Listener的类必须使用下列的几个接口
ServletContextListener
ServletContextAttributeListener
ServletRequestListener
ServletRequestAttributeListener
HttpSessionListener
HttpSessionAttributeListener
例子：
package com.hotusm.web.listener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
@WebListener
public class MyHttpSessionListener implements HttpSessionListener{
@Override
public void sessionCreated(HttpSessionEvent se) {
System.out.println("创建session ");
}
@Override
public void sessionDestroyed(HttpSessionEvent se) {
System.out.println("销毁session ");
}
} |
这样，在我们启动的时候 就会自动的帮助我们创建一个Listener了，这个注解有一个属性，是这个listener的描述信息
2.@WebFilter 这个注解就是表示的拦截器 同样的也是直接注解在写好的Filter上面就ok了。
package com.hotusm.web.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
@WebFilter(filterName = "filter1", urlPatterns="/*",
dispatcherTypes = {DispatcherType.REQUEST, DispatcherType.FORWARD},
initParams={@WebInitParam(name="account",value="1234"),@WebInitParam(name="hotusm",value="1234")}
)
public class MyFilter implements Filter {
@Override
public void init(final FilterConfig filterConfig) throws ServletException {
String account = filterConfig.getInitParameter("account");
String hotusm = filterConfig.getInitParameter("hotusm");
System.out.println("account:"+account+" hotusm:"+hotusm);
}
@Override
public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain) throws IOException, ServletException {
chain.doFilter(request, response);
}
@Override
public void destroy() {
}
} |
注解的主要参数及其含义
3.@WebServlet 这个注解表示的就是一般的Servlet
package com.hotusm.web.servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
@WebServlet(name = "servlet1", urlPatterns = {"/url1", "/url2","url3/*"}, loadOnStartup = 1,
initParams = {
@WebInitParam(name = "name", value="hotusm")
})
public class MyServlet extends HttpServlet {
private String name;
public MyServlet() {
System.out.println("load on startup");
}
@Override
public void init() throws ServletException {
super.init();
name= this.getInitParameter("name");
}
@Override
protected void doGet(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
System.out.println(session);
System.out.println("name:"+name);
}
} |
注解主要参数
参数和Filter差不多
4.其中在上面的注解Filter和Servlet用到的@WebInitParam 注解 表示的就是参数啦 相当于<init-param>
参数以及含义
5.@MultipartConfig 该注解主要是为了辅助 Servlet 3.0 中 HttpServletRequest 提供的对上传文件的支持。该注解标注在 Servlet 上面，以表示该 Servlet 希望处理的请求的 MIME 类型是 multipart/form-data。另外，它还提供了若干属性用于简化对上传文件的处理。具体如下：
例子：
<form action="upload" enctype="multipart/form-data" method="POST">
<input name="file" type="file" />
<input type="submit" value="Upload" />
</form>
package com.hotusm.web.servlet;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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;
@MultipartConfig(location="C://upload")
@WebServlet(name="upload",urlPatterns={"/upload"})
public class UploadServlet extends HttpServlet{
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html; charset=UTF-8");
PrintWriter out = resp.getWriter();
Part part = req.getPart("file");
String fileName = part.getHeader("content-disposition");
System.out.println(fileName);
System.out.println(fileName.substring(fileName.lastIndexOf(File.separator)+1, fileName.length()-1));
part.write( fileName.substring(fileName.lastIndexOf(File.separator)+1, fileName.length()-1));
out.write("{'type':'1','msg':'success'}");
}
} |
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Java技术网站 → 『 Java开发技术 』 → 『 Java Web开发技术专题 』 → Servlet3.0的注解
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