web入门-servlet 3.0注解 文件上传

1.Servlet注解@WebServlet

name

value

urlPatterns

loadOnstartup

initPatterns

asyncSupported    开启异步处理需要设置为true

description

displayName

@WebServlet(name="SaverServlet",urlPatterns="/SaveServlet")

public class servlet implements HttpServlet{

...doGet(),doPost()

}

2.Filter注解@WebFilter

filterName

value

urlPatterns

servletNames

initParams

asyncSupported   开启异步处理需要设置为true

description

displayName

dispatcherTypes

@WebServlet(filterName="char",urlPatterns="/*")

public class CharFilter implements Filter{

...

}

3Listener注解@WebListener
@WebListener("value")

public class MyContentListener implements ServletContextListener{

...

}

4.InitParam注解@WebInitParam

name

value

description

@WebServlet(urlPatterns="/simple",name="SimpleServlet",initParams=@WebInitParam(name="username",value="tom"))

public class SimpleServlet extends HttpServlet{

...

}

5.对文件上传支持的注解@MultipartConfig

fileSizeThreshold    当文件大于该值时，内容将被写入文件

location 存放生成的文件地址

maxFileSize 允许上传的文件最大值，默认-1，即没限制

maxRequestSize针对该multipart/form-data 请求的最大数量，默认-1，即没限制

@WebServlet("/UploadServlet")

@MultipartConfig(location="d:/tmp")

public class UploadServlet extends HttpServlet{

private static final long serialVersionUID=1L;

protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{

response.setContentType(“text/html;charset=UTF-8”);

PrintWriter out =response.getWriter();

String path =this.getServletContext().getRealPath("/");  //获取服务器地址

Part p=request,getPart("filename");  //获取文件    前台web页面中file input  的  name

if(p.getContentType().contains("image")){

ApplicationPart ap=(ApplicationPart)p;

String fname1=ap.getFilename();

int path_idx=fname1.lastIndexOf("\\")+1;

String fname2=fname1.substring(path_idx,fname1.length());

p.write(path+"upload/"+fname2);

out.write("文件上传成功");

}

else{

out.write("请选择图片文件");

}

}

}