Java Reference
In-Depth Information
Example 3−6: RemoveHTMLReader.java (continued)
boolean intag = false;
// Used to remember whether we are "inside" a tag
/**
* This is the implementation of the no-op read() method of FilterReader.
* It calls in.read() to get a buffer full of characters, then strips
* out the HTML tags. (in is a protected field of the superclass).
**/
public int read(char[] buf, int from, int len) throws IOException {
int numchars = 0; // how many characters have been read
// Loop, because we might read a bunch of characters, then strip them
// all out, leaving us with zero characters to return.
while (numchars == 0) {
numchars = in.read(buf, from, len); // Read characters
if (numchars == -1) return -1;
// Check for EOF and handle it.
// Loop through the characters we read, stripping out HTML tags.
// Characters not in tags are copied over previous tags
int last = from; // Index of last non-HTML char
for(int i = from; i < from + numchars; i++) {
if (!intag) { // If not in an HTML tag
if (buf[i] == '<') intag = true; // check for tag start
else buf[last++] = buf[i];
// and copy the character
}
else if (buf[i] == '>') intag = false; // check for end of tag
}
numchars = last - from; // Figure out how many characters remain
}
// And if it is more than zero characters
return numchars;
// Then return that number.
}
/**
* This is another no-op read() method we have to implement. We
* implement it in terms of the method above. Our superclass implements
* the remaining read() methods in terms of these two.
**/
public int read() throws IOException {
char[] buf = new char[1];
int result = read(buf, 0, 1);
if (result == -1) return -1;
else return (int)buf[0];
}
/** This class defines a main() method to test the RemoveHTMLReader */
public static class Test {
/** The test program: read a text file, strip HTML, print to console */
public static void main(String[] args) {
try {
if (args.length != 1)
throw new IllegalArgumentException("Wrong number of args");
// Create a stream to read from the file and strip tags from it
BufferedReader in = new BufferedReader(
new RemoveHTMLReader(new FileReader(args[0])));
// Read line by line, printing lines to the console
String line;
while((line = in.readLine()) != null)
System.out.println(line);
in.close(); // Close the stream.
}
