servlet3.0的学习（三）
文件的上传Upload.java
import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.PrintWriter;import java.util.UUID;import javax.servlet.ServletConfig;import javax.servlet.ServletException;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;@WebServlet(urlPatterns = {"/upload"})public class Upload extends HttpServlet { @Override public void init(ServletConfig config) throws ServletException { super.init(config); } @Override protected void service(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException { PrintWriter out = res.getWriter(); InputStream is = null; FileOutputStream fos = null; String targetDirectory = req.getServletContext().getRealPath("/upload"); try { for (Part p : req.getParts()) { UUID id = UUID.randomUUID(); out.write("Part name: " + p.getName() + "<br/>\n"); out.write("Size: " + p.getSize() + "<br/>\n"); out.write("Content Type: " + p.getContentType() + "<br/>\n"); is = p.getInputStream(); File file = new File(targetDirectory, id.toString() + ".jpg"); fos = new FileOutputStream(file); out.write("Header Names:"); for (String name : p.getHeaderNames()) { out.write(" " + name); } out.write("<br/><br/>\n"); while (true) { int bytedata = is.read(); if (bytedata == '\n') out.write("<br/>"); if (bytedata == -1) { break; } fos.write(bytedata); } } } finally { if (is != null) { is.close(); } if (out != null) { out.close(); } } }}
index.html
<html><head><title>File Upload Example</title></head><body><form action="upload" method="post" enctype="multipart/form-data"> <h3>Choose files to upload.</h3> <input name="myFile" type="file" /> <br/> <input name="myFile2" type="file"/> <br/> <br/> <input value="upload" type="submit"/> <input type="reset"/> <br/></form></body></html>
讲解：javax.servlet.http.Interface Part，这个接口主要是用来接收提交形式为multipart/form-data POST 请求.
void delete() ：删除一个文件项目的底层存储，包括删除任何相关的临时磁盘文件
java.lang.String getContentType()：获取内容类型，如image/x-png，
application/octet-stream
java.lang.String getHeader(java.lang.String name)：返回指定的MIME头
java.util.Collection<java.lang.String> getHeaderNames()：获取本部分的头名。
java.io.InputStream getInputStream()：返回当前文件的输入流
java.lang.String getName()：获取文件名，input的name
long getSize()：获取大小
void write(java.lang.String fileName)：写入本地硬盘，如果有多个文件需要保存时次方法并不能保证成功
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