Java reads binary files in bytes, and can also read pictures, music files, video files, etc. In Java, four categories are provided to operate files, namely InputStream, OutputStream, Reader, and Writer. The first two are operations on byte streams, and the latter two are operations on character streams.
FileWriter can only accept parameters in the form of strings, which means it can only save the content to a text file. Compared with text files, file storage in binary format saves more space.
InputStream is used to read data from the input stream in bytes. The int read() method reads a byte, which returns a value between 0 and 255 in the form of an integer. Why read a byte instead of directly returning a byte type value?
Because the highest bit of the byte type is the sign bit, the largest positive integer it can represent is 127.
InputStream is just an abstract class and cannot be instantiated. FilelnputStream is a subclass of InputStream and is used to read bytes from a file.
public static void main(String[] args) throws IOException {
String filePath = "d:/test.txt";
File file = new File (filePath); //根據文件路徑創(chuàng)建一個文件對象
//如果找不到文件，會拋出FileNotFoundException異常
FilelnputStream filelnput = new FilelnputStream(file);
}
filelnput.close (); //關閉文件輸入流，如果無法正常關閉，會拋出IOException異常The write(int b) method in OutputStream is used to write out data by bytes. FileOutputStream is used to write data to a file in bytes. For example, reading the content from a file by bytes and writing it to another new file is the file copy function.
File fileln = new File ("source. txt"); //打開源文件
File fileOut = new File ("target.txt”）； //打開寫入文件，也就是目標文件
FilelnputStream streamln = new FilelnputStream (fileln); //根據源文件構建輸入流
FileOutputStream streamOut = new FileOutputStream (fileOut); //根據目標文件構建輸出流
int c;
//從源文件中按字節(jié)讀入數據，如果內容還沒讀完，則繼續(xù)
while ((c = streamln.read()) != -1) {
streamOut .write (c); //寫入目標文件
}
streamln.close。； //關閉輸入流
streamOut.close(); //關閉輸出流Determine whether the file already exists. If it does not exist, generate the file.
File dataFile = new File(dicDir + dataDic);
if (!dataFile.exists()) {
//如果文件不存在則寫入文件
}Use the File.mkdirs() method to create multi-level directories. For example, when a directory does not exist, create it.
File tempDir = new File(imgPath);
if(!tempDir.exists()){
tempDir.mkdirs();
}Many java training videos, all on the PHP Chinese website, welcome to learn online!
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