js读取本地图片进行预览，上传服务器

import java.io.FileOutputStream; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import sun.misc.BASE64Decoder; /** * 上传图片。 */ public class UploadImageAjax extends HttpServlet { private static final long serialVersionUID = 1L; @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{ String image = req.getParameter("image"); // 只允许jpg String header = "data:image/jpeg;base64,"; if(image.indexOf(header) != 0){ resp.getWriter().print(wrapJSON(false)); return; } // 去掉头部 image = image.substring(header.length()); // 写入磁盘 boolean success = false; BASE64Decoder decoder = new BASE64Decoder(); try{ byte[] decodedBytes = decoder.decodeBuffer(image); String imgFilePath = "D://uploadimage.jpg"; FileOutputStream out = new FileOutputStream(imgFilePath); out.write(decodedBytes); out.close(); success = true; }catch(Exception e){ success = false; e.printStackTrace(); } resp.getWriter().print(wrapJSON(success)); } private String wrapJSON(boolean success){ return "{\"success\":" + success + "}"; } }