JavaIO系统(一）

@FunctionalInterface
public interface FilenameFilter {
    boolean accept(File dir, String name);
}

public String[] list(FilenameFilter filter) {
    // 策略模式，根据filter是否为null，具有不同的策略
    String names[] = list();
    if ((names == null) || (filter == null)) {
        return names;
    }
    // 内部使用了ArrayList
    List<String> v = new ArrayList<>();
    for (int i = 0 ; i < names.length ; i++) {
        if (filter.accept(this, names[i])) {
            v.add(names[i]);
        }
    }
    return v.toArray(new String[v.size()]);
    }

package Note.iosystem;

import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.Pattern;

class DirFilter implements FilenameFilter {
    private Pattern pattern;
    DirFilter (String regex){
        pattern = Pattern.compile(regex);
    }
    @Override
    public boolean accept(File dir, String name) {
        return pattern.matcher(name).matches();
    }
}

public class DirList {
    public static void main(String[] args) {
        File file = new File("./src/Note/iosystem");
        String filter = ".*\\.java";
        String [] filenames = file.list(new DirFilter(filter));
        assert filenames != null;
        for (String filename:filenames
             ) {
            System.out.println(filename);
        }
    }
}

package Note.iosystem;

import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.Pattern;

public class DirList2 {
    public static void main(String[] args) {
        File file = new File("./src/Note/iosystem");
        String filter = ".*\\.java";
        String [] filenames = file.list(new FilenameFilter() {
            private Pattern pattern  = Pattern.compile(filter);
            @Override
            public boolean accept(File dir, String name) {
                return pattern.matcher(name).matches();
            }
        });
        assert filenames != null;
        for (String filename:filenames
        ) {
            System.out.println(filename);
        }
    }
}

public static void main(String[] args) {
        // Java 中一个 “\” 表示转义开始
        File file = new File("E:\\桌面文件\\JAVA\\src\\demo.txt");
    }

File file1 = new File("E:\\桌面文件\\JAVA\\src", "demo.txt");

File file2 = new File("E:\\桌面文件\\JAVA\\src");
File file3 = new File(file2, "demo.txt");

package Note.iosystem;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class CopyFile {

    private String sourcePath, targetPath;
    CopyFile (String source, String target) {
        sourcePath = source;
        targetPath = target;
    }

    public void copy() throws IOException {
        FileInputStream fis = new FileInputStream(this.sourcePath);
        // 构造器第二个参数append传递true表示开启追加写模式
        FileOutputStream fos = new FileOutputStream(this.targetPath, true);
        byte [] bytes = new byte[1024];
        int readResult = 0;
        while(readResult >= 0) {
            // read方法传递一个长度为n的字节数组，每次读取n位， 返回实际读取的位数，读到
            // 文件结束符返回 -1
            readResult  = fis.read(bytes);
            if(readResult > 0) {
                // write方法可以传递一个偏移量和长度，表示写比特数组的0位开始，
                // 长度为readResult的数据
                fos.write(bytes, 0, readResult);
            }
        }
        // 记得要关闭流对象
        fis.close();
        fos.close();
    }

    public static void main(String[] args) throws IOException {
        CopyFile copyFile = new CopyFile("E:\\桌面文件\\媒体\\生而为人.m4a",
                "E:\\桌面文件\\生而为人.m4a");
        copyFile.copy();
    }

}

package Note.iosystem;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class CopyFileByChar {
    private String sourcePath, targetPath;
    CopyFileByChar (String source, String target) {
        sourcePath = source;
        targetPath = target;
    }

    public void copy() throws IOException {
        FileReader fr = new FileReader(this.sourcePath);
        FileWriter fw = new FileWriter(this.targetPath, true);
        int readResult = 0;
        char [] chars = new char[1024];
        while(readResult >= 0) {
            readResult = fr.read(chars);
            if(readResult > 0){
                fw.write(chars, 0, readResult);
            }

        }
        fr.close();
        fw.close();
    }

    public static void main(String[] args) throws IOException {
        CopyFileByChar copyFileByChar = new CopyFileByChar("./src/Note/iosystem/DirList.java",
                "./src/Note/iosystem/DirListCopyByChar.txt");
        copyFileByChar.copy();
    }
}

package Note.iosystem;

import java.io.*;

public class BufferDemo {
    private String from, to;
    public BufferDemo(String from, String to) {
        this.from = from;
        this.to = to;
    }

    public void copy() throws IOException {
        BufferedReader bfr = new BufferedReader(new FileReader(this.from));
//        char [] chars = new char[1024];
//        bfr.read(chars);
        BufferedWriter bfw = new BufferedWriter(new FileWriter(this.to));
        String line = bfr.readLine();
        while (line != null) {
            bfw.write(line);
            bfw.newLine();
            line = bfr.readLine();
        }
        bfr.close();
        bfw.close();
    }

    public static void main(String[] args) throws IOException {
        BufferDemo bd = new BufferDemo("./src/Note/iosystem/DirList.java",
                "./src/Note/iosystem/DirListCopyByChar.txt");
        bd.copy();
    }
}

package Note.iosystem;

import java.io.*;

public class ConversionStream {
    public static void main(String[] args) throws IOException {
        String filePath = "./src/Note/iosystem/DirList.java";
        String filePathGBK = "./src/Note/iosystem/DirListGBK.java";
        InputStreamReader isr = new InputStreamReader(new FileInputStream(filePath));
        OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream(filePathGBK), "GBK");
        char [] chars = new char[1024];
        int result = isr.read(chars);
        while (result >= 0) {
            osw.write(chars);
            result = isr.read(chars);
        }
        isr.close();
        osw.close();
    }
}

    private final static long serialVersionUID = 1L;

package Note.iosystem.serialization;

import java.io.Serializable;

public class Person implements Serializable {
    private String name;
    private transient int age;

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    public Person(String n, int a) {
        this.age = a;
        this.name = n;
    }
}

package Note.iosystem.serialization;

import java.io.*;

public class ObjectOSDemo {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        String outputPath = "./src/Note/iosystem/objectOutput";
        Person person = new Person("zhangSan", 17);
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(outputPath));
        oos.writeObject(person);
        oos.close();

        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(outputPath));
        Person p = (Person) ois.readObject();
        System.out.println(p);
        ois.close();
    }
}