java 读取文件编码问题

在项目中遇到要读取文本文件内容然后批量查询，但每当在后台读取上传文件流时，第一个内容总会有一个？如：

？test0

test1

而实际内容应该是：

test0

test1.

经过查找资料，有了下面解决方式：

BufferedReader nickContent = new BufferedReader(new UnicodeReader(mFileItem.getInputStream(),Charset.defaultCharset().name()));

 

UnicodeReader.java
import java.io.*;
    /**
     * Generic unicode textreader, which will use BOM mark
     * to identify the encoding to be used. If BOM is not found
     * then use a given default or system encoding.
     */
    public class UnicodeReader extends Reader {
        PushbackInputStream internalIn;
        InputStreamReader   internalIn2 = null;
        String              defaultEnc;


        private static final int BOM_SIZE = 4;


        /**
         *
         * @param in  inputstream to be read
         * @param defaultEnc default encoding if stream does not have
         *                   BOM marker. Give NULL to use system-level default.
         */
        public UnicodeReader(InputStream in, String defaultEnc) {
            internalIn = new PushbackInputStream(in, BOM_SIZE);
            this.defaultEnc = defaultEnc;
        }


        public String getDefaultEncoding() {
            return defaultEnc;
        }


        /**
         * Get stream encoding or NULL if stream is uninitialized.
         * Call init() or read() method to initialize it.
         */
        public String getEncoding() {
            if (internalIn2 == null) return null;
            return internalIn2.getEncoding();
        }


        /**
         * Read-ahead four bytes and check for BOM marks. Extra bytes are
         * unread back to the stream, only BOM bytes are skipped.
         */
        protected void init() throws IOException {
            if (internalIn2 != null) return;


            String encoding;
            byte bom[] = new byte[BOM_SIZE];
            int n, unread;
            n = internalIn.read(bom, 0, bom.length);


            if ( (bom[0] == (byte)0x00) && (bom[1] == (byte)0x00) &&
                    (bom[2] == (byte)0xFE) && (bom[3] == (byte)0xFF) ) {
                encoding = "UTF-32BE";
                unread = n - 4;
            } else if ( (bom[0] == (byte)0xFF) && (bom[1] == (byte)0xFE) &&
                    (bom[2] == (byte)0x00) && (bom[3] == (byte)0x00) ) {
                encoding = "UTF-32LE";
                unread = n - 4;
            } else if (  (bom[0] == (byte)0xEF) && (bom[1] == (byte)0xBB) &&
                    (bom[2] == (byte)0xBF) ) {
                encoding = "UTF-8";
                unread = n - 3;
            } else if ( (bom[0] == (byte)0xFE) && (bom[1] == (byte)0xFF) ) {
                encoding = "UTF-16BE";
                unread = n - 2;
            } else if ( (bom[0] == (byte)0xFF) && (bom[1] == (byte)0xFE) ) {
                encoding = "UTF-16LE";
                unread = n - 2;
            } else {
                // Unicode BOM mark not found, unread all bytes
                encoding = defaultEnc;
                unread = n;
            }
            //System.out.println("read=" + n + ", unread=" + unread);


            if (unread > 0) internalIn.unread(bom, (n - unread), unread);


            // Use given encoding
            if (encoding == null) {
                internalIn2 = new InputStreamReader(internalIn);
            } else {
                internalIn2 = new InputStreamReader(internalIn, encoding);
            }
        }


        public void close() throws IOException {
            init();
            internalIn2.close();
        }


        public int read(char[] cbuf, int off, int len) throws IOException {
            init();
            return internalIn2.read(cbuf, off, len);
        }
}