How Java io reads and writes files

Java abstracts the data of these different sources and targets into data streams; the Java language input and output functions are very powerful and flexible; In the Java class Library, the IO section is very large because it involves a wide range of fields: standard input and output, file manipulation, data flow on the network, string flow, Object flow, zip file stream.

Here are a few ways to read and write files:

First, InputStream, OutputStream (Byte stream)

//read file (Byte stream)InputStream in =NewFileInputStream ("D:\\1.txt");//write the appropriate fileOutputStream out =NewFileOutputStream ("D:\\2.txt");//reading Data//How many bytes are taken at oncebyte[] bytes =New byte[2048];//Accept the Read content (n represents the relevant data, but the form of a number)intn =-1;//Loop out Data while((n = in.read (bytes,0,bytes.length))! =-1) {    //Convert to StringString str =NewString (Bytes,0,n, "GBK");    #这里可以实现字节到字符串的转换, Comparative practical System.out.println (str); //Writing related filesOut.write (Bytes, 0, n);}//Close the streamin.close (); Out.close ();

Second, Bufferedinputstream, Bufferedoutputstream (cache byte stream) use the same way as the byte stream, but more efficient (recommended)

//read file (cache byte stream)Bufferedinputstream in =NewBufferedinputstream (NewFileInputStream ("D:\\1.txt"));//write the appropriate fileBufferedoutputstream out =NewBufferedoutputstream (NewFileOutputStream ("D:\\2.txt"));//reading Data//How many bytes are taken at oncebyte[] bytes =New byte[2048];//Accept the Read content (n represents the relevant data, but the form of a number)intn =-1;//Loop out Data while((n = in.read (bytes,0,bytes.length))! =-1) {    //Convert to StringString str =NewString (Bytes,0,n, "GBK");    System.out.println (str); //Writing related filesOut.write (Bytes, 0, n);}//Clear CacheOut.flush ();//Close the streamin.close (); Out.close ();

Third, InputStreamReader, OutputStreamWriter (byte stream, this way is not recommended, not directly read and write bytes). Use ranges for character conversions

//read file (Byte stream)InputStreamReader in =NewInputStreamReader (NewFileInputStream ("D:\\1.txt"), "GBK");//write the appropriate fileOutputStreamWriter out =NewOutputStreamWriter (NewFileOutputStream ("D:\\2.txt"));//reading Data//Loop out Databyte[] bytes =New byte[1024];intLen =-1; while(len = In.read ())! =-1) {System.out.println (len); //Writing related filesOut.write (len);}//Clear CacheOut.flush ();//Close the streamin.close (); Out.close ();

Iv. FileReader, FileWriter (provides a small amount of text reading and writing)

Try{    //Write a text file using the FileWriter classFileWriter writer=NewFileWriter (fileName); Writer.write ("Hello kuka:\n"); Writer.write ("My name is coolszy!\n"); Writer.write ("I like you and miss." "); Writer.close ();} Catch(IOException e) {e.printstacktrace ();}Try{    //Use the FileWriter class to append information to a text fileFileWriter writer =NewFileWriter (FileName,true); SimpleDateFormat format=NewSimpleDateFormat (); String Time= Format.format (NewDate ()); Writer.write ("\n\t" +Time ); Writer.close ();} Catch(IOException e) {e.printstacktrace ();}intC=0;Try{    //using the FileReader class to read a text fileFileReader reader=NewFileReader (fileName); C=Reader.read ();  while(C!=-1) {System.out.print (Char) c); C=Reader.read (); } reader.close ();} Catch(Exception e) {e.printstacktrace ();}

Five, BufferedReader, BufferedWriter (Cache stream, provides ReadLine method to read a line of text)

//Read file (character stream)BufferedReader in =NewBufferedReader (NewInputStreamReader (NewFileInputStream ("D:\\1.txt"), "GBK") ); #这里主要是涉及中文//BufferedReader in = new BufferedReader (New FileReader ("D:\\1.txt" ));//write the appropriate fileBufferedWriter out =NewBufferedWriter (NewOutputStreamWriter (NewFileOutputStream ("D:\\2.txt"), "GBK"));//BufferedWriter out = new BufferedWriter (New FileWriter ("D:\\2.txt"));//reading Data//Loop out DataString str =NULL; while(str = in.readline ())! =NULL) {System.out.println (str); //Writing related filesout.write (str);　　Out.newline (); //Note that the line-wrapping effect does not necessarily occur on various computers

// Clear Cache  // Close Flow in.close (); Out.close ();

Six, Reader, PrintWriter (PrintWriter This is very useful, in writing data colleagues can format)

//read file (Byte stream)Reader in =NewInputStreamReader (NewFileInputStream ("D:\\1.txt"), "GBK");//write the appropriate filePrintWriter out =NewPrintWriter (NewFileWriter ("D:\\2.txt"));//reading Data//Loop out Databyte[] bytes =New byte[1024];intLen =-1; while(len = In.read ())! =-1) {System.out.println (len); //Writing related filesOut.write (len);}//Clear CacheOut.flush ();//Close the streamin.close (); Out.close ();

How Java io reads and writes files