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java: read file and insert content

Posted on 2008-11-03
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Last Modified: 2013-11-23
I have a html file that I am reading in using filereader/bufferedreader.  I want to add content to the file when the first <body> tag is read.  What would the logic be for this condition and inserting data?
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Question by:newbieal
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by:Kevin Cross
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Using filereader/bufferedreader you would have to create separate code using the writer versions of these classes (i.e. FileWriter) that will write the data to another file.  Since the buffered reader is giving each line one at a time, you would just insert your data through writer when you have read/written the opening body tag.
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by:Kevin Cross
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These may be helpful for you:

Java Tutorials -- Basic I/O:
http://java.sun.com/docs/books/tutorial/essential/io/

Java Practices -- Reading and Writing Files:
http://www.javapractices.com/topic/TopicAction.do?Id=42
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by:newbieal
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Thank you, but none of the examples demonstrate insertion of text at a particular point.
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by:newbieal
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This is what I have so far. The text is appended at the end of the file and not after the <body> tag.
BufferedReader bIn = new BufferedReader(new FileReader(

			    "testing.html"));

		String line = bIn.readLine();

		while (line != null) {

			

		if(line.contains("<body>"))

		{

			createOrAppendFile("testing.html", "some text");

		}

		line = bIn.readLine();

		}

	}

	   private static void createOrAppendFile (String f, String text) throws IOException {  

		   BufferedWriter bw = new BufferedWriter (new FileWriter (f, true));  

		   bw.write (text);  

		   bw.newLine();  

		   bw.flush();  

		   bw.close();  

		   }  

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Kevin Cross earned 500 total points
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+Think you want to write to a different file.  You could always delete old and rename new one to old name at the end, but safer this way IMHO.
+Not sure you can insert data that way.  IIRC, the method you are using will write data at the end since you have the append option set to true.  Again, this may not be wrong if you are using a different file, since the text contained would only be up to point you have read and written from your other file so append would be right to insert data.

When you write to different file, you will see that you will need to write the original line data in first then do check for if you are at the <body> line and then insert additional data then when you code continues in loop it will write the remainder of the HTML thus leaving your new data inserted immediately after the <body> tag.
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by:newbieal
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Ok, I found this code that seems to do what I am looking for, however I need to insert content after the <body> tag.  How do I determine the line at which the content needs inserted? In this example the line number is provided via input.

http://www.java-tips.org/java-se-tips/java.io/insert-a-line-in-a-file.html
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by:Kevin Cross
Kevin Cross earned 500 total points
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That is basically the concept -- as you can see they are reading in the file and writing one line at a time to the new file then at the end they delete and rename.

In their case, a simple line number works.  For you though, you need logic like you have above to check if line contains "<body>" in its text.  To mimic what they are doing you have to change the logic around i++ to set the a temp string that has the contents of the line you have just written then the next time through it will check if temp string equals/contains string you are looking then write extra line(s) of data.

Then will continue to write lines of data until file is fully recreated.
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by:newbieal
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The <body> tag may contain some additional info, eg. <body lang=EN-US style='tab-interval:.5in'>

When I check for the tag what expression to I need to check it against so that my new values aren't inserted within the body tag.
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by:Kevin Cross
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You will probably need to look into writing a regular expression to check for "<body" + any amount of characters + ">".
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by:newbieal
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Yeah, that's what I thought.  Do you have an example of a regex for my specific case?
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by:Kevin Cross
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You can try "<body[a-zA-Z0-9]*>" but I would give it a try it and then create a question in the regular expressions zone...

Hopefully that helps!
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