1,java 讀取 xml utf-8 編碼格式的檔案,出現  Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; 前言中不允許有內容。

    出現這樣的原因, 是因為讀取檔案過程中,出現了格式轉化問題,在程式碼中,需要進行轉化處理. 對utf-8編碼格式或者utf-8 無bom編碼格式,要有對應的讀取處理.

步驟一: 

       先進行封裝一個java類. 這個類的主要作用是 對 utf8 編碼格式進行處理,在首行 新增 bom 格式相關資訊,大約三個位元組.

  package com.sdzx.controller;


import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;


public class UnicodeInputStream extends InputStream {
    PushbackInputStream internalIn;
    boolean             isInited = false;
    String              defaultEnc;
    String              encoding;


     private static final int BOM_SIZE = 4;


     public UnicodeInputStream(InputStream in, String defaultEnc) {
         internalIn = new PushbackInputStream(in, BOM_SIZE);
         this.defaultEnc = defaultEnc;
     }


     public String getDefaultEncoding() {
       return defaultEnc;
    }


    public String getEncoding() {
       if (!isInited) {
          try {
             init();
          } catch (IOException ex) {
             IllegalStateException ise = new IllegalStateException("Init method failed.");
             ise.initCause(ise);
             throw ise;
          }
       }
       return encoding;
    }


    /**
     * 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 (isInited) return;


       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);


       isInited = true;
    }


    public void close() throws IOException {
       //init();
       isInited = true;
       internalIn.close();
    }


    public int read() throws IOException {
       //init();
       isInited = true;
       return internalIn.read();
    }
 }

步驟二:    採用以下讀取xml檔案處理.

           /**

             // URL 引數,如果以http開始,就用http://+"檔案絕對路徑" ,如果是本地檔案,則要用ftp:/// +"檔案絕對路徑" 開頭

          */

         URL url = new URL("http://****/***/test.txt");    

 　　　// File f  = new File("test.txt");  

        String enc = null; // or NULL to use systemdefault
        UnicodeInputStream uin = new UnicodeInputStream(url.openStream(),enc);  //如果是本地將url.openStream -> new FileInputStream(f)
        enc = uin.getEncoding(); // check and skip possible BOM bytes
        InputStreamReader in;
        if (enc == null){
            in = new InputStreamReader(uin);
        }else {
            in = new InputStreamReader(uin, enc);
        }
        BufferedReader reader = new BufferedReader(in);
        //BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("D:/tags.txt"),"utf-8"));
        String tmp =reader.readLine();

這樣讀取的結果就是正常的了， 

  以上  : 轉載於    https://www.cnblogs.com/xifenglou/p/6233689.html