48
49 /**
50 * Special interface for data authentication
51 */
52 public static interface Authenticate
53 {
54 /**
55 * Method used in ICUBinary.readHeader() to provide data format
56 * authentication.
57 * @param version version of the current data
58 * @return true if dataformat is an acceptable version, false otherwise
59 */
60 public boolean isDataVersionAcceptable(byte version[]);
61 }
62
63 // public methods --------------------------------------------------------
64
65 /**
66 * <p>ICU data header reader method.
67 * Takes a ICU generated big-endian input stream, parse the ICU standard
68 * file header and authenticates them.</p>
69 * <p>Header format:
70 * <ul>
71 * <li> Header size (char)
72 * <li> Magic number 1 (byte)
73 * <li> Magic number 2 (byte)
74 * <li> Rest of the header size (char)
75 * <li> Reserved word (char)
76 * <li> Big endian indicator (byte)
77 * <li> Character set family indicator (byte)
78 * <li> Size of a char (byte) for c++ and c use
79 * <li> Reserved byte (byte)
80 * <li> Data format identifier (4 bytes), each ICU data has its own
81 * identifier to distinguish them. [0] major [1] minor
82 * [2] milli [3] micro
83 * <li> Data version (4 bytes), the change version of the ICU data
84 * [0] major [1] minor [2] milli [3] micro
85 * <li> Unicode version (4 bytes) this ICU is based on.
86 * </ul>
87 * </p>
88 * <p>
89 * Example of use:<br>
90 * <pre>
91 * try {
92 * FileInputStream input = new FileInputStream(filename);
93 * If (Utility.readICUDataHeader(input, dataformat, dataversion,
94 * unicode) {
95 * System.out.println("Verified file header, this is a ICU data file");
96 * }
97 * } catch (IOException e) {
98 * System.out.println("This is not a ICU data file");
99 * }
100 * </pre>
101 * </p>
102 * @param inputStream input stream that contains the ICU data header
103 * @param dataFormatIDExpected Data format expected. An array of 4 bytes
104 * information about the data format.
105 * E.g. data format ID 1.2.3.4. will became an array of
106 * {1, 2, 3, 4}
107 * @param authenticate user defined extra data authentication. This value
108 * can be null, if no extra authentication is needed.
109 * @exception IOException thrown if there is a read error or
110 * when header authentication fails.
111 * @draft 2.1
112 */
113 public static final byte[] readHeader(InputStream inputStream,
114 byte dataFormatIDExpected[],
115 Authenticate authenticate)
116 throws IOException
117 {
118 DataInputStream input = new DataInputStream(inputStream);
119 char headersize = input.readChar();
120 int readcount = 2;
121 //reading the header format
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48
49 /**
50 * Special interface for data authentication
51 */
52 public static interface Authenticate
53 {
54 /**
55 * Method used in ICUBinary.readHeader() to provide data format
56 * authentication.
57 * @param version version of the current data
58 * @return true if dataformat is an acceptable version, false otherwise
59 */
60 public boolean isDataVersionAcceptable(byte version[]);
61 }
62
63 // public methods --------------------------------------------------------
64
65 /**
66 * <p>ICU data header reader method.
67 * Takes a ICU generated big-endian input stream, parse the ICU standard
68 * file header and authenticates them.
69 * <p>Header format:
70 * <ul>
71 * <li> Header size (char)
72 * <li> Magic number 1 (byte)
73 * <li> Magic number 2 (byte)
74 * <li> Rest of the header size (char)
75 * <li> Reserved word (char)
76 * <li> Big endian indicator (byte)
77 * <li> Character set family indicator (byte)
78 * <li> Size of a char (byte) for c++ and c use
79 * <li> Reserved byte (byte)
80 * <li> Data format identifier (4 bytes), each ICU data has its own
81 * identifier to distinguish them. [0] major [1] minor
82 * [2] milli [3] micro
83 * <li> Data version (4 bytes), the change version of the ICU data
84 * [0] major [1] minor [2] milli [3] micro
85 * <li> Unicode version (4 bytes) this ICU is based on.
86 * </ul>
87 *
88 * <p>
89 * Example of use:<br>
90 * <pre>
91 * try {
92 * FileInputStream input = new FileInputStream(filename);
93 * If (Utility.readICUDataHeader(input, dataformat, dataversion,
94 * unicode) {
95 * System.out.println("Verified file header, this is a ICU data file");
96 * }
97 * } catch (IOException e) {
98 * System.out.println("This is not a ICU data file");
99 * }
100 * </pre>
101 *
102 * @param inputStream input stream that contains the ICU data header
103 * @param dataFormatIDExpected Data format expected. An array of 4 bytes
104 * information about the data format.
105 * E.g. data format ID 1.2.3.4. will became an array of
106 * {1, 2, 3, 4}
107 * @param authenticate user defined extra data authentication. This value
108 * can be null, if no extra authentication is needed.
109 * @exception IOException thrown if there is a read error or
110 * when header authentication fails.
111 * @draft 2.1
112 */
113 public static final byte[] readHeader(InputStream inputStream,
114 byte dataFormatIDExpected[],
115 Authenticate authenticate)
116 throws IOException
117 {
118 DataInputStream input = new DataInputStream(inputStream);
119 char headersize = input.readChar();
120 int readcount = 2;
121 //reading the header format
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