Summary of Java Foundation-io (ii) outline pending update

First, the use of buffer streams

　　Each byte stream has a corresponding buffer stream:

　　

　　Bufferedinputstream/bufferedoutputstream

　　Constructor:

　　

　　

　　The method summary is similar to the corresponding node stream

Using buffered streams for File replication: in practice

@Test Public voidtestBuffered1 () {//also need to associate files first, note text using reader Writer, non-text using FIS fosFile file1 =NewFile ("D:\\test\\1.jpg"); File file2=NewFile ("D:\\test\\2.jpg"); Bufferedinputstream bis=NULL; Bufferedoutputstream Bos=NULL; Try {            //Create a node streamFileInputStream FIS =NewFileInputStream (FILE1); FileOutputStream Fos=NewFileOutputStream (file2); //wrapping a node stream as a buffered streambis =NewBufferedinputstream (FIS); Bos=NewBufferedoutputstream (FOS); //prepare the buffered array            byte[] bytes =New byte[20]; intLen;  while(len = bis.read (bytes))! =-1) {bos.write (bytes,0, Len); //After you finish, refresh the finalBos.flush (); }        } Catch(IOException e) {e.printstacktrace (); } finally {            //Close the stream, pay attention to the closing order of the stream, and automatically close the corresponding node stream when the buffer stream is closed directly            if(Bos! =NULL) {                Try{bos.close (); } Catch(IOException e) {e.printstacktrace (); }            }            if(bis! =NULL) {                Try{bis.close (); } Catch(IOException e) {e.printstacktrace (); }            }        }    }

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　The use of BufferedReader and BufferedWriter is similar to the corresponding node stream

　　Demonstrates a unique ReadLine method:

@Test Public voidTestbufferedreader () {File file1=NewFile ("D:\\test\\hello.txt"); BufferedReader BR=NULL; Try{FileReader fr=NewFileReader (FILE1); BR=NewBufferedReader (FR); //operation using BR-Unique read lineString s =NULL;  while((s = br.readline ())! =NULL) {System.out.println (s); }        } Catch(IOException e) {e.printstacktrace (); } finally {            if(BR! =NULL) {                Try{br.close (); } Catch(IOException e) {e.printstacktrace (); }            }        }    }

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　　Note that a byte stream is required to read the doc document (even if the document is all text, Doc is no longer a plain text file)

Second, the use of the conversion stream

　　Inputstreamreader/outputstreamwriter

　　The JDK is described below: the process of coding and decoding needs to be clarified

InputStreamReader is a bridge of byte flow to a character stream: it reads the bytes with the specified charset and decodes them to characters. The character set it uses can be specified or explicitly given by name, or it can accept the default character set of the platform. Each call to a read () method in InputStreamReader causes one or more bytes to be read from the underlying input stream. To enable a valid conversion from byte to character, you can read more bytes in advance from the underlying stream to exceed the bytes required to satisfy the current read operation. In order to achieve maximum efficiency, it is necessary to consider packaging InputStreamReader within the BufferedReader. Example: BufferedReader in=NewBufferedReader (NewInputStreamReader (system.in)); OutputStreamWriter is a bridge of character flow to a byte stream: You can encode the characters in the stream to be written into bytes using the specified charset. The character set it uses can be specified by name or explicitly given, otherwise the platform default character set will be accepted. Each call to the write () method causes the encoding converter to be called on the given character (or character set). The resulting bytes are accumulated in the buffer before writing to the underlying output stream. You can specify the size of this buffer, but the default buffer is large enough for most purposes. Note that the characters passed to the write () method are not buffered. For maximum efficiency, consider wrapping the outputstreamwriter into BufferedWriter to avoid frequent calls to the converter. Example: Writer out=NewBufferedWriter (NewOutputStreamWriter (System.out)); The proxy pair is a character, it consists of twoCharValue Sequence representation: The range of the high surrogate is ' \ud800 ' to ' \UDBFF ', followed by the range ' \udc00 ' to ' \udfff 'Low-surrogate. The error proxy element refers to a high surrogate that is not followed by a low surrogate, or a low surrogate that has no previous high surrogate. This class always replaces the error proxy element and the non-mapped character sequence with the default substitution sequence for the character set. If you need more control over the encoding process, you should use the Charsetencoder class. 

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　　Decoding, the solution to what we can understand, that is, to solve the string

A simple example is as follows: (not particularly important, not specifically introduced here)

@Test Public voidtest1 () {File file=NewFile ("D:\\test\\hello.txt"); //Exception Handling TemporaryFileInputStream FIS =Newfileinputstream (file); //decoding of Byte stream to character streamsInputStreamReader ISR =NewInputStreamReader (FIS, "GBK"); BufferedReader BR=NewBufferedReader (ISR);        String s; //the operation of the buffered stream is omitted}

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III. standard input/output stream

　　Which is our common syetem.out/in.

　　Example of receiving user input using:

@Test Public voidtest1 () {bufferedreader br=NULL; Try{InputStream in=system.in; //convert into a character streamInputStreamReader ISR =NewInputStreamReader (in); BR=NewBufferedReader (ISR);            String s;  while(true) {System.out.println ("Please enter a string:"); S=Br.readline (); if("Exit". Equalsignorecase (s)) {                     Break; } String S1=s.touppercase ();            System.out.println (S1); }        } Catch(IOException e) {e.printstacktrace (); } finally {            if(BR! =NULL) {                Try{br.close (); } Catch(IOException e) {e.printstacktrace (); }            }        }    }

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Summary of Java Foundation-io (ii) outline pending update