fileupload.java

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        ret = 1;
        files.removeAllElements();

        int allFileSize = 0;

        ServletInputStream in = request.getInputStream();
        final int maxcount = 2048; //一行的最大字节数1024,如果设为128会使得当上传文件的路径比较长时被截断
        byte[] line = new byte[maxcount];
        byte[] oldline = new byte[maxcount];

        int oldi;
        int i = in.readLine(line, 0, maxcount);

        if (debug) {
            //写入文件，调试用
            File f2 = new File("c:/redmoon_fileupload.txt");
            FileOutputStream os2;
            os2 = new FileOutputStream(f2);
            while (i != -1) {
                String d = new String(line, 0, i);
                os2.write(d.getBytes("ISO-8859-1"));
                i = in.readLine(line, 0, maxcount);
            }
            os2.close();
            if (true) {
                return -1;
            }
        }

        if (i < 3) { // 第一行小于3则上传出错
            ret = this.RET_FAIL;
            return ret;
        }

        int boundaryLength = i - 2; // 去除换行回车

        String boundary = new String(line, 0, boundaryLength); //-2是为了丢弃换行字符
        fields = new Hashtable();

        /**
         * Web站点主目录的位置为<%=request.getRealPath("/")%>
         JSP网页所在的目录位置<%=request.getRealPath("./")%>
         JSP网页所在目录上一层目录的位置<%=request.getRealPath("../")%>
         */
        // 检查临时文件目录是否存在，不存在，则创建
        if (tmpPath==null) {
            String rootPath = application.getRealPath("/");
            tmpPath = rootPath + "FileUploadTmp/";
            File f = new File(tmpPath);
            if (!f.isDirectory()) {
                f.mkdirs();
            }
        }

        while (i != -1) {
            String newLine = new String(line, 0, i); //第一行
            if (newLine.startsWith("Content-Disposition: form-data; name=\"")) {
                if (newLine.indexOf("filename=\"") != -1) {
                    // 获取上传的文件
                    int pos = newLine.indexOf("name=\"");
                    String fieldName = newLine.substring(pos + 6,
                            newLine.length() - 3);
                    // 此时 fieldName = filename1"; filename="C:\Documents and Settings\Administrator\My Documents\My Pictures\forum_isnews.gif
                    int index = fieldName.indexOf("\";");
                    fieldName = fieldName.substring(0, index);
                    fieldName = new String(fieldName.getBytes(), charset);
                    parseFileName(new String(line, 0, i - 2, charset));
                    if (filename == null) {
                        // 未上传文件
                        i = in.readLine(line, 0, maxcount);
                        continue;
                    }
                    if (filename != null && !isValidExtname(extname)) {
                        if (debug) {
                            System.out.println("extname=" + extname);
                        }
                        ret = this.RET_INVALIDEXT; // 扩展名非法
                        return ret;
                    }
                    i = in.readLine(line, 0, maxcount);
                    setContentType(new String(line, 0, i - 2));
                    i = in.readLine(line, 0, maxcount); // 读空行

                    i = in.readLine(line, 0, maxcount);
                    newLine = new String(line, 0, i);

                    // StringBuffer filedata = new StringBuffer(1000); //文件数据
                    long thisfilesize = 0;

                    // 创建临时文件
                    String tmpFileName = getRandName() + "." + extname;
                    String tmpFilePath = tmpPath + tmpFileName;

                    // 记录临时文件的路径
                    tmpFiles.addElement(tmpFilePath);

                    File tmpFile = new File( tmpFilePath );
                    FileOutputStream os2;
                    os2 = new FileOutputStream(tmpFile);

                    while (i != -1 && !newLine.startsWith(boundary)) {
                        oldi = i;
                        for (int k = 0; k < i; k++) {
                            oldline[k] = line[k]; // 复制line
                        }

                        i = in.readLine(line, 0, maxcount);
                        if ((i == boundaryLength + 2 || i == boundaryLength + 4)
                            && (new String(line, 0, i).startsWith(boundary))) { //如果是所有数据的最后一行或分界符
                            // filedata.append(new String(oldline, 0, oldi - 2,
                            //        "ISO-8859-1"));
                            os2.write(oldline, 0, oldi-2);

                            allFileSize += oldi - 2;
                            thisfilesize += oldi - 2;
                        } else {
                            // filedata.append(new String(oldline, 0, oldi,
                            //         "ISO-8859-1"));
                            os2.write(oldline, 0, oldi);

                            allFileSize += oldi;
                            thisfilesize += oldi;
                        }
                        newLine = new String(line, 0, i);

                        // if (filedata.length() > fileSize * 1024) { // 图片尺寸要小于fileSize K
                        if (thisfilesize > fileSize * 1024) {
                            // 此处直接退出，当文件太大时会导致客户端出现“找不到服务器”错误，可能是因为in未readline所有request中的数据而致使产生浏览器报DNS错误
                            in.close();
                            tmpFile.delete();
                            os2.close();
                            ret = this.RET_TOOLARGESINGLE;
                            return ret;
                        }

                        // 如果超过预定上传文件总的大小
                        if (maxAllFileSize != -1 &&
                            allFileSize > maxAllFileSize * 1024) {
                            ret = this.RET_TOOLARGEALL;
                            tmpFile.delete();
                            os2.close();
                            return ret;
                        }
                    }
                    //if (filedata.length()>fileSize*1024)//图片尺寸要小于fileSize
                    //	  ret = -3;		//放在此处不会出现找不到服务器的DNS错误，但是如果文件很大的话就很耗资源

                    // 关闭临地文件写入流
                    os2.close();

                    if (thisfilesize == 0) {
                        if (debug) {
                            System.out.println("FileUpload 文件" + filename + "长度为 0 ！");
                        }
                        continue;
                    }

                    FileInfo fi = new FileInfo();
                    fi.fieldName = fieldName;
                    fi.name = filename;
                    fi.ext = extname;
                    fi.setTmpFilePath(tmpFilePath);

                    // fi.data = filedata.toString();
                    fi.contentType = contentType;
                    fi.size = thisfilesize; // 或者filedata.length();//以K为单位
                    if (debug) {
                        System.out.println(fi.name + ": " + fi.size + " " +
                                           fi.ext + " " + fi.contentType);
                    }
                    files.addElement(fi);
                } else {
                    // 获取表单域的值
                    int pos = newLine.indexOf("name=\"");
                    String fieldName = newLine.substring(pos + 6,
                            newLine.length() - 3);

                    i = in.readLine(line, 0, maxcount);
                    i = in.readLine(line, 0, maxcount);
                    // System.out.println("reqeust getCharacterEncoding: " + request.getCharacterEncoding()); // 取得的值为null

                    newLine = new String(line, 0, i, charset);
                    // newLine = new String(line, 0, i);

                    StringBuffer fieldValue = new StringBuffer(maxcount);

                    while (i != -1 && !newLine.startsWith(boundary)) {
                        // 最后一行包含换行字符
                        // 因此我们必须检查当前行是否是最后一行
                        i = in.readLine(line, 0, maxcount);
                        if ((i == boundaryLength + 2 || i == boundaryLength + 4)
                            && (new String(line, 0, i).startsWith(boundary))) {
                            fieldValue.append(newLine.substring(0,
                                    newLine.length() - 2));
                        } else {
                            fieldValue.append(newLine);
                        }
                        // newLine = new String(line, 0, i);
                        newLine = new String(line, 0, i, charset);
                    }
                    // String fv = new String(fieldValue.toString().getBytes("ISO8859_1"), charset);
                    // fields.put(fieldName, fv);
                    Object obj = fields.get(fieldName);
                    if (obj!=null) {
                        // 如果为字符串
                        if (obj.getClass().isInstance(new String(""))) {
                            Vector v = new Vector();
                            v.addElement(obj); // 第一个对应于filed的值
                            v.addElement(fieldValue.toString());
                            fields.put(fieldName, v);
                        }
                        else {
                            Vector v = (Vector) obj;
                            v.addElement(fieldValue.toString());
                        }
                    }
                    else
                        fields.put(fieldName, fieldValue.toString());
                }
            }
            i = in.readLine(line, 0, maxcount);
        }
        in.close();
        return ret;
    }

    /**
     * 写入文件
     * @param isRandName 是否用随机的文件名
     */
    public void writeFile(boolean isRandName) {
        int size = files.size();
        if (size == 0) {
            return;
        }

        File f = new File(savePath);
        if (!f.isDirectory()) {
            f.mkdirs();
        }

        java.util.Enumeration e = files.elements();
        while (e.hasMoreElements()) {
            FileInfo fi = (FileInfo) e.nextElement();
            if (!isRandName) {
                fi.write(savePath);
            } else { //防止文件名重复
                fi.write(savePath,
                         getRandName() + "." + fi.getExt());
            }
        }
    }

    /**
     * 生成唯一数字ID
     * @return
     */
    public static String getRandName() {
        // 根据时间值，重置hash，否则hash会无限增大
        if (System.currentTimeMillis()-lastRandTime>20000)
            hash.clear();
        Integer id = new Integer(0);
        synchronized (hash) {
            // 生成一个唯一的随机数字
            id = new Integer(rand.nextInt());
            while (hash.containsKey(id)) {
                id = new Integer(rand.nextInt());
            }
            // 为当前用户保留该ID
            String data = "";
            hash.put(id, data);
        }
        lastRandTime = System.currentTimeMillis();
        return System.currentTimeMillis() + "" + Math.abs(id.intValue());
    }

    /**
     * 从上传的文件路径获取文件名
     * Windows浏览器发送完整的文件路径和名字
     * 但Linux/Unix和Mac浏览器只发送文件名字
     * @param filePath String
     * @param isIE bool 是否为IE
     * @return String
     */
    public static String getUploadFileName(String filePath) {
        String fileName = "";
        int pos = filePath.lastIndexOf("\\");
        if (pos != -1) {
            fileName = filePath.substring(pos + 1);
        } else {
            fileName = filePath;
        }

        return fileName;
    }

    public static String getFileExt(String fileName) {
        // 下面取到的扩展名错误，只有三位，而如html的文件则有四位
        // extName = fileName.substring(fileName.length() - 3, fileName.length()); //扩展名
        int dotindex = fileName.lastIndexOf(".");
        String extName = fileName.substring(dotindex + 1, fileName.length());
        extName = extName.toLowerCase(); //置为小写
        return extName;
    }

    private int maxAllFileSize = -1; // 等于-1表示上传总大小不受限制

    private String realPath;
    private static String tmpPath = null;
}