编辑：我已经在GitHub上发布了正确的版本：https : //github.com/gpakosz/UnipreBOMInputStream
这是我之前编码的一个类，我只是在粘贴之前编辑了程序包名称。没什么特别的，它与SUN的错误数据库中发布的解决方案非常相似。将其合并到您的代码中就可以了。
package com.stackoverflow.answer;import java.io.IOException;import java.io.InputStream;import java.io.PushbackInputStream;public class UnipreBOMInputStream extends InputStream{ public static final class BOM { public static final BOM NONE = new BOM(new byte[]{},"NONE"); public static final BOM UTF_8 = new BOM(new byte[]{(byte)0xEF,(byte)0xBB,(byte)0xBF},"UTF-8"); public static final BOM UTF_16_LE = new BOM(new byte[]{ (byte)0xFF, (byte)0xFE}, "UTF-16 little-endian"); public static final BOM UTF_16_BE = new BOM(new byte[]{ (byte)0xFE, (byte)0xFF}, "UTF-16 big-endian"); public static final BOM UTF_32_LE = new BOM(new byte[]{ (byte)0xFF, (byte)0xFE, (byte)0x00, (byte)0x00}, "UTF-32 little-endian"); public static final BOM UTF_32_BE = new BOM(new byte[]{ (byte)0x00, (byte)0x00, (byte)0xFE, (byte)0xFF}, "UTF-32 big-endian"); public final String toString() { return description; } public final byte[] getBytes() { final int length = bytes.length; final byte[] result = new byte[length]; // Make a defensive copy System.arraycopy(bytes,0,result,0,length); return result; } private BOM(final byte bom[], final String description) { assert(bom != null) : "invalid BOM: null is not allowed"; assert(description != null) : "invalid description: null is not allowed"; assert(description.length() != 0) : "invalid description: empty string is not allowed"; this.bytes = bom; this.description = description; } final byte bytes[]; private final String description; } // BOM public UnipreBOMInputStream(final InputStream inputStream) throws NullPointerException, IOException { if (inputStream == null) throw new NullPointerException("invalid input stream: null is not allowed"); in = new PushbackInputStream(inputStream,4); final byte bom[] = new byte[4]; final int read = in.read(bom); switch(read) { case 4: if ((bom[0] == (byte)0xFF) && (bom[1] == (byte)0xFE) && (bom[2] == (byte)0x00) && (bom[3] == (byte)0x00)) { this.bom = BOM.UTF_32_LE; break; } else if ((bom[0] == (byte)0x00) && (bom[1] == (byte)0x00) && (bom[2] == (byte)0xFE) && (bom[3] == (byte)0xFF)) { this.bom = BOM.UTF_32_BE; break; } case 3: if ((bom[0] == (byte)0xEF) && (bom[1] == (byte)0xBB) && (bom[2] == (byte)0xBF)) { this.bom = BOM.UTF_8; break; } case 2: if ((bom[0] == (byte)0xFF) && (bom[1] == (byte)0xFE)) { this.bom = BOM.UTF_16_LE; break; } else if ((bom[0] == (byte)0xFE) && (bom[1] == (byte)0xFF)) { this.bom = BOM.UTF_16_BE; break; } default: this.bom = BOM.NONE; break; } if (read > 0) in.unread(bom,0,read); } public final BOM getBOM() { // BOM type is immutable. return bom; } public final synchronized UnipreBOMInputStream skipBOM() throws IOException { if (!skipped) { in.skip(bom.bytes.length); skipped = true; } return this; } public int read() throws IOException { return in.read(); } public int read(final byte b[]) throws IOException, NullPointerException { return in.read(b,0,b.length); } public int read(final byte b[], final int off, final int len) throws IOException, NullPointerException { return in.read(b,off,len); } public long skip(final long n) throws IOException { return in.skip(n); } public int available() throws IOException { return in.available(); } public void close() throws IOException { in.close(); } public synchronized void mark(final int readlimit) { in.mark(readlimit); } public synchronized void reset() throws IOException { in.reset(); } public boolean markSupported() { return in.markSupported(); } private final PushbackInputStream in; private final BOM bom; private boolean skipped = false;} // UnipreBOMInputStream您正在以这种方式使用它：
import java.io.BufferedReader;import java.io.FileInputStream;import java.io.InputStreamReader;public final class UnipreBOMInputStreamUsage{ public static void main(final String[] args) throws Exception { FileInputStream fis = new FileInputStream("test/offending_bom.txt"); UnipreBOMInputStream ubis = new UnipreBOMInputStream(fis); System.out.println("detected BOM: " + ubis.getBOM()); System.out.print("Reading the content of the file without skipping the BOM: "); InputStreamReader isr = new InputStreamReader(ubis); BufferedReader br = new BufferedReader(isr); System.out.println(br.readLine()); br.close(); isr.close(); ubis.close(); fis.close(); fis = new FileInputStream("test/offending_bom.txt"); ubis = new UnipreBOMInputStream(fis); isr = new InputStreamReader(ubis); br = new BufferedReader(isr); ubis.skipBOM(); System.out.print("Reading the content of the file after skipping the BOM: "); System.out.println(br.readLine()); br.close(); isr.close(); ubis.close(); fis.close(); }} // UnipreBOMInputStreamUsage
