What does io stream mean in Java?

1. Input stream, data can only be read from it, but data cannot be written to it. An output stream can only write byte data, but not read from it.

2.InputStream types are:

ByteArrayInputStream     包含一个内存缓冲区，字节从中取出。
FileInputStream          从文件中获得字节。
ObjectInputStream        用来恢复被序列化的对象。
PipedInputStream         管道输入流，读取管道内容。多和PipedOutputStream一起用于多线程通信。
SequenceInputStream      是多种输入流的逻辑串联，从第一个输入流读取，直到最后一个输入流。
StringBufferInputStream  读取的字节由字符串提供。

2.OutputStream types are also as follows:

ByteArrayOutputStream     该类实现了一个输出流，其数据被写入由byte数组充当的缓冲区，缓冲区会随着数据的不断写入而自动增长。
FileOutputStream          该类实现了一个输出流，其数据写入文件。
ObjectOutputStream        该类将实现了序列化的对象序列化后写入指定地方。
PipedOutputStream         管道的输出流，是管道的发送端。

3.Objectstream, InputStream is often used together with FileInputStream and FileOutputStream. (Used during initialization)

ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("Logon.out"));

4. The File class does not refer to a file, but also represents the name of a series of files. If it represents a file set, the list() method can be used to query the set. .

5. StreamTokenizer is used to split any InputStream into a series of numbers. StringTokenizer provides a very similar function to StreamTokenizer, but it is for strings. It feels similar to C#'s split() method.

6. Steps to use Zip to compress files:

First generate the compressed file:

FileOutputStream f =new FileOutputStream("test.zip");
CheckedOutputStream csum =new CheckedOutputStream(
f, new Adler32());
ZipOutputStream out =new ZipOutputStream(new BufferedOutputStream(csum));

out.setComment("A test of Java Zipping");//压缩文件注释信息

Then add the files to be compressed Go in:

out.putNextEntry(new ZipEntry(test.txt);

If necessary, you can continue to write other things to the file, but you must ensure that there is already a ZipEntry class in the out class.

Source code:

import java.io.*;import java.util.*;import java.util.zip.*;public class ZipCompress {public static void main(String[] args) {try {
            FileOutputStream fileOutputStream = new FileOutputStream("test.zip");
            CheckedOutputStream csum = new CheckedOutputStream(fileOutputStream, new Adler32());
            ZipOutputStream outputStream = new ZipOutputStream(new BufferedOutputStream(csum));
            outputStream.setComment("A test of java Zipping");
            System.out.println("Writing file" + "zip.txt");
            BufferedReader in = new BufferedReader(new FileReader("zip.txt"));
            outputStream.putNextEntry(new ZipEntry("zip.txt"));// int c;// while ((c = in.read()) != -1) {// outputStream.write(c);// }// in.close();outputStream.write("123".getBytes());
            outputStream.close();
            System.out.println("Checksum:" + csum.getChecksum().getValue());
            System.out.println("Reading file");
            FileInputStream fileInputStream = new FileInputStream("test.zip");
            CheckedInputStream csumi = new CheckedInputStream(fileInputStream, new Adler32());
            ZipInputStream in2 = new ZipInputStream(new BufferedInputStream(csumi));
            ZipEntry zipEntry;
            System.out.println("Checksum:" + csumi.getChecksum().getValue());while ((zipEntry = in2.getNextEntry()) != null) {
                System.out.println("Reading file:" + zipEntry);int x;while ((x = in2.read()) != -1) {
                    System.out.println(x);
                }

            }

            in2.close();

            ZipFile zf = new ZipFile("test.zip");
            Enumeration e = zf.entries();while (e.hasMoreElements()) {
                ZipEntry ze2 = (ZipEntry) e.nextElement();
                System.out.println("File: " + ze2);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

7. The difference between Serialization and Externalizable interfaces. Both are interfaces that can serialize classes. The difference is that Serialization will Serialize all objects, and Externalizable can control the serialized part, that is, partial serialization.

8.Serialization control serialization method: (1) Apply the transient (temporary) keyword.

(2) We can implement the Serializable interface and add (note that "add" instead of "cover" or "implementation") the method of ") or") and readObject (). Once the object is serialized or reassembled, those two methods will be called respectively.

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