您需要编写FilterInputStream 以在 SAX 解析器获取数据之前过滤数据。它必须删除或重新编码不良数据。
Apache 有一个super-flexible 示例。您可能希望组装一个更简单的。
这是我的一个，它可以做其他清理工作，但我相信这将是一个好的开始。
/* Cleans up often very bad xml.
*
* 1. Strips leading white space.
* 2. Recodes £ etc to &#...;.
* 3. Recodes lone & as &.
*
*/
public class XMLInputStream extends FilterInputStream {
private static final int MIN_LENGTH = 2;
// Everything we've read.
StringBuilder red = new StringBuilder();
// Data I have pushed back.
StringBuilder pushBack = new StringBuilder();
// How much we've given them.
int given = 0;
// How much we've read.
int pulled = 0;
public XMLInputStream(InputStream in) {
super(in);
}
public int length() {
// NB: This is a Troll length (i.e. it goes 1, 2, many) so 2 actually means "at least 2"
try {
StringBuilder s = read(MIN_LENGTH);
pushBack.append(s);
return s.length();
} catch (IOException ex) {
log.warning("Oops ", ex);
}
return 0;
}
private StringBuilder read(int n) throws IOException {
// Input stream finished?
boolean eof = false;
// Read that many.
StringBuilder s = new StringBuilder(n);
while (s.length() < n && !eof) {
// Always get from the pushBack buffer.
if (pushBack.length() == 0) {
// Read something from the stream into pushBack.
eof = readIntoPushBack();
}
// Pushback only contains deliverable codes.
if (pushBack.length() > 0) {
// Grab one character
s.append(pushBack.charAt(0));
// Remove it from pushBack
pushBack.deleteCharAt(0);
}
}
return s;
}
// Returns false at eof.
// Might not actually push back anything but usually will.
private boolean readIntoPushBack() throws IOException {
// File finished?
boolean eof = false;
// Next char.
int ch = in.read();
if (ch >= 0) {
// Discard whitespace at start?
if (!(pulled == 0 && isWhiteSpace(ch))) {
// Good code.
pulled += 1;
// Parse out the &stuff;
if (ch == '&') {
// Process the &
readAmpersand();
} else {
// Not an '&', just append.
pushBack.append((char) ch);
}
}
} else {
// Hit end of file.
eof = true;
}
return eof;
}
// Deal with an ampersand in the stream.
private void readAmpersand() throws IOException {
// Read the whole word, up to and including the ;
StringBuilder reference = new StringBuilder();
int ch;
// Should end in a ';'
for (ch = in.read(); isAlphaNumeric(ch); ch = in.read()) {
reference.append((char) ch);
}
// Did we tidily finish?
if (ch == ';') {
// Yes! Translate it into a &#nnn; code.
String code = XML.hash(reference);
if (code != null) {
// Keep it.
pushBack.append(code);
} else {
throw new IOException("Invalid/Unknown reference '&" + reference + ";'");
}
} else {
// Did not terminate properly!
// Perhaps an & on its own or a malformed reference.
// Either way, escape the &
pushBack.append("&").append(reference).append((char) ch);
}
}
private void given(CharSequence s, int wanted, int got) {
// Keep track of what we've given them.
red.append(s);
given += got;
log.finer("Given: [" + wanted + "," + got + "]-" + s);
}
@Override
public int read() throws IOException {
StringBuilder s = read(1);
given(s, 1, 1);
return s.length() > 0 ? s.charAt(0) : -1;
}
@Override
public int read(byte[] data, int offset, int length) throws IOException {
int n = 0;
StringBuilder s = read(length);
for (int i = 0; i < Math.min(length, s.length()); i++) {
data[offset + i] = (byte) s.charAt(i);
n += 1;
}
given(s, length, n);
return n > 0 ? n : -1;
}
@Override
public String toString() {
String s = red.toString();
String h = "";
// Hex dump the small ones.
if (s.length() < 8) {
Separator sep = new Separator(" ");
for (int i = 0; i < s.length(); i++) {
h += sep.sep() + Integer.toHexString(s.charAt(i));
}
}
return "[" + given + "]-\"" + s + "\"" + (h.length() > 0 ? " (" + h + ")" : "");
}
private boolean isWhiteSpace(int ch) {
switch (ch) {
case ' ':
case '\r':
case '\n':
case '\t':
return true;
}
return false;
}
private boolean isAlphaNumeric(int ch) {
return ('a' <= ch && ch <= 'z')
|| ('A' <= ch && ch <= 'Z')
|| ('0' <= ch && ch <= '9');
}
}