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21 package au.id.jericho.lib.html;
22
23 import java.util.*;
24 import java.io.*;
25 import java.net.*;
26
27
32 final class EncodedSource {
33 public final Reader Reader;
34 public final String  Encoding;
35 public final String EncodingSpecificationInfo;
36 public final HttpURLConnection HttpURLConnection;
37
38 private static final int PREVIEW_BUFFER_SIZE=2048;
39 private static final int PREVIEW_MAX_BYTES=PREVIEW_BUFFER_SIZE*4;
41 private static final String UTF_32="UTF-32"; private static final String UTF_16="UTF-16";
43 private static final String UTF_16BE="UTF-16BE";
44 private static final String UTF_16LE="UTF-16LE";
45 private static final String UTF_8="UTF-8";
46 private static final String EBCDIC="Cp037";
47 private static final String ISO_8859_1="ISO-8859-1";
48
49 EncodedSource(final InputStream inputStream, final String encoding, final String encodingSpecificationInfo, final HttpURLConnection httpURLConnection) throws UnsupportedEncodingException {
50 if (encoding==null)
51 Reader=new InputStreamReader(inputStream); else
53 Reader=new InputStreamReader(inputStream,encoding);
54 Encoding=encoding;
55 EncodingSpecificationInfo=encodingSpecificationInfo;
56 HttpURLConnection=httpURLConnection;
57 }
58
59 public static EncodedSource construct(final URL url) throws IOException {
60 final URLConnection urlConnection=url.openConnection();
61 final HttpURLConnection httpURLConnection=(urlConnection instanceof HttpURLConnection) ? (HttpURLConnection)urlConnection : null;
62 final InputStream inputStream=urlConnection.getInputStream();
64 final String contentType=urlConnection.getContentType();
65 if (contentType!=null) {
66 final String charset=Source.getCharsetParameterFromHttpHeaderValue(contentType);
67 if (charset!=null) return new EncodedSource(inputStream,charset,"HTTP header Content-Type: "+contentType,httpURLConnection);
68 }
69 return construct(inputStream,httpURLConnection);
70 }
71
72 public static EncodedSource construct(final InputStream inputStream, final HttpURLConnection httpURLConnection) throws IOException {
73 final BufferedInputStream in=(inputStream instanceof BufferedInputStream) ? (BufferedInputStream)inputStream : new BufferedInputStream(inputStream);
74 in.mark(PREVIEW_MAX_BYTES);
75 final String preliminaryEncoding=getPreliminaryEncoding(in);
76 if (preliminaryEncoding==null) return new EncodedSource(in,null,"empty input stream",httpURLConnection);
77 in.reset();
78 final Source previewSource=getPreviewSource(in,preliminaryEncoding);
79 in.reset();
80 if (previewSource.getEncoding()!=null) return new EncodedSource(in,previewSource.encoding,previewSource.encodingSpecificationInfo,httpURLConnection);
81 if (httpURLConnection!=null && preliminaryEncoding==UTF_8 && !previewSource.isXML())
85 return new EncodedSource(in,ISO_8859_1,"HTTP default 8-bit encoding for non-XML document",httpURLConnection);
86 return new EncodedSource(in,preliminaryEncoding,"XML default matching first four bytes of input stream",httpURLConnection);
88 }
89
90 private static String getPreliminaryEncoding(BufferedInputStream bufferedInputStream) throws IOException {
91 final int b1=bufferedInputStream.read();
92 if (b1==-1) return null;
93 final int b2=bufferedInputStream.read();
94 final int b3=bufferedInputStream.read();
95 final int b4=bufferedInputStream.read();
96 if ((b1&0xFE)==0xFE && b2==(b1^1)) { return (b3==0) ? UTF_32 : UTF_16;
98 } else if (b1==0) {
99 if (b2==0 || b4==0) return UTF_32;
100 return UTF_16BE;
101 } else if (b2==0) {
102 return (b3==0) ? UTF_32 : UTF_16LE;
103 } else if (b1==0x4C && b2==0x6F && b3==0xA7 && b4==0x94) return EBCDIC; return UTF_8;
105 }
106
107 private static Source getPreviewSource(BufferedInputStream bufferedInputStream, String preliminaryEncoding) throws IOException {
108 final BufferedReader preliminaryReader=new BufferedReader(new InputStreamReader(bufferedInputStream,preliminaryEncoding),PREVIEW_BUFFER_SIZE);
109 StringBuffer sb=new StringBuffer (PREVIEW_BUFFER_SIZE);
110 for (int i=0; i<PREVIEW_BUFFER_SIZE; i++) {
111 final int ch=preliminaryReader.read();
112 if (ch==-1) break;
113 sb.append((char)ch);
114 }
115 return new Source(sb);
116 }
117 }
118 |
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