java常用的io，输入输出

package _8javaio;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.*;
import java.util.Arrays;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

public class Main {
    public static byte[] getFileDataAsBytes(File f)
    {
        byte[] data = new byte[(int)f.length()];
        try(InputStream is =new FileInputStream(f))
        {
            int n;
            while((n=is.read(data))!=-1)
            {
                System.out.println("read"+n+"bytes");
            }

        }catch(IOException e)
        {
            e.printStackTrace();
        }
        return data;
    }
    static void printFiles(File[] files) {
        System.out.println("==========");
        if (files != null) {
            for (File f : files) {
                System.out.println(f);
            }
        }
        System.out.println("==========");
    }

    public static void main(String[] args) throws Exception{
        //File对象
        File f = new File("..");
        System.out.println(f.getPath());         //构造方法传入路径
        System.out.println(f.getAbsolutePath()); //返回绝对路径
        System.out.println(f.getCanonicalPath());//返回规范绝对路径
        System.out.println(File.separator);      //返回当前平台系统路径分隔符

//        File f1 = new File("C:\\Windows");
//        File f2 = new File("C:\\Windows\\notepad.exe");
//        File f3 = new File("C:\\Windows\\nothing");
//        System.out.println(f1.isFile());      //false 文件
//        System.out.println(f1.isDirectory()); //true  目录
//        System.out.println(f2.isFile());      //true
//        System.out.println(f2.isDirectory()); //false
//        System.out.println(f3.isFile());      //false
//        System.out.println(f3.isDirectory()); //false


        //文件权限和大小
//        System.out.println(f2.canRead());   //是否可读
//        System.out.println(f2.canWrite());  //是否可写
//        System.out.println(f2.canExecute());//是否可执行
//        System.out.println(f2.length());    //文件字节大小

        //创建删除文件
        File file = new File("test/test.txt"); //与src同一级
        if (file.createNewFile()) {
            // 文件创建成功:
            System.out.println("create success");
            System.out.println(file.getAbsolutePath());
            // TODO:
            if (file.delete()) {
                // 删除文件成功:
                System.out.println("delete success");
            }
        }

        //创建临时文件
//        File f4 = File.createTempFile("tmp-", ".txt"); // 提供临时文件的前缀和后缀
//        f4.deleteOnExit(); // JVM退出时自动删除
//        System.out.println(f4.isFile());
//        System.out.println(f4.getAbsolutePath());

        //遍历文件和目录
//        File f5 = new File("C:Windows");
//
//        File[] fs1 = f5.listFiles(); // 列出所有文件和子目录
//        printFiles(fs1);
//        File[] fs2 = f5.listFiles(new FilenameFilter() { // 仅列出.exe文件
//            public boolean accept(File dir, String name) {
//                return name.endsWith(".exe"); // 返回true表示接受该文件
//            }
//        });
//        printFiles(fs2);

        //创建和删除目录
        new File("hello").mkdir();
        new File("hello/le").mkdirs();
        new File("hello/le").delete();
        new File("hello").delete();


        //Path
        Path p1 = Paths.get(".", "project", "study"); // 构造一个Path对象
        System.out.println(p1);
        Path p2 = p1.toAbsolutePath(); // 转换为绝对路径
        System.out.println(p2);
        Path p3 = p2.normalize(); // 转换为规范路径
        System.out.println(p3);
        File f6 = p3.toFile(); // 转换为File对象
        System.out.println(f6);
        for (Path p : Paths.get("..").toAbsolutePath()) { // 可以直接遍历Path
            System.out.println("  " + p);
        }


        /**InputStream*/
        //字节读文件
        // 创建一个FileInputStream对象:
        File file2 = new File("test/readme.txt");
        file2.createNewFile();
        try (InputStream input = new FileInputStream("test/readme.txt")) {
            int n;
            while ((n = input.read()) != -1) {
                System.out.println(n);
            }
        } // 编译器在此自动为我们写入finally并调用close()


        //缓冲读文件
        try (InputStream input = new FileInputStream("test/readme.txt")) {
            // 定义1000个字节大小的缓冲区:
            byte[] buffer = new byte[1000];
            int n;
            while ((n = input.read(buffer)) != -1) { // 读取到缓冲区
                System.out.println("read " + n + " bytes.");
            }
        }
        //模拟InputStream
        String s;
        byte[] data = { 72, 101, 108, 108, 111, 33 };
        try (InputStream input = new ByteArrayInputStream(data)) {
            int n;
            StringBuilder sb = new StringBuilder();
            while ((n = input.read()) != -1) {
                sb.append((char) n);
                System.out.println((char)n);
            }
            s = sb.toString();
        }
        System.out.println(s);


        /**OutputStream*/
        //一次写入一个字节
        OutputStream output = new FileOutputStream("test/readme.txt");
        output.write(72); // H
        output.write(101); // e
        output.write(108); // l
        output.write(108); // l
        output.write(111); // o
        output.close();

        //一次写入若干字节
        try (OutputStream output1 = new FileOutputStream("test/readme.txt")) {
            output1.write("Hello！".getBytes("UTF-8")); // Hello
        } // 编译器在此自动为我们写入finally并调用close()

        //模拟OutputStream
        byte[] data3;
        try (ByteArrayOutputStream output3 = new ByteArrayOutputStream()) {
            output3.write("Hello ".getBytes("UTF-8"));
            output3.write("world!".getBytes("UTF-8"));
            data3 = output3.toByteArray();
        }
        System.out.println(new String(data3, "UTF-8"));


        //Filter模式
        InputStream file7 = new FileInputStream("test/test.gz");
        InputStream buffered = new BufferedInputStream(file7);
        InputStream gzip = new GZIPInputStream(buffered);
        System.out.println(gzip);
        file7.close();

        /**操作Zip*/
        //读取zip
        try (ZipInputStream zip = new ZipInputStream(new FileInputStream("test/test.zip"))) {
            ZipEntry entry = null;
            while ((entry = zip.getNextEntry()) != null) {
                String name = entry.getName();
                System.out.println("name："+name);
                if (!entry.isDirectory()) {
                    int n;
                    while ((n = zip.read()) != -1) {
                        System.out.println(n);
                    }
                }
            }
        }
        //写入zip
        try (ZipOutputStream zip = new ZipOutputStream(new FileOutputStream("test/log.zip"))) {
            File ff = new File("log");
            File[] files = ff.listFiles();
            for (File file1 : files) {
                zip.putNextEntry(new ZipEntry(file1.getName()));
                zip.write(getFileDataAsBytes(file1));
                zip.closeEntry();
            }
        }

        /**序列化*/
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        try (ObjectOutputStream output1 = new ObjectOutputStream(buffer)) {
            // 写入int:
            output1.writeInt(12345);
            // 写入String:
            output1.writeUTF("Hello");
            // 写入Object:
            output1.writeObject(Double.valueOf(123.456));
        }
        System.out.println(Arrays.toString(buffer.toByteArray()));


        /**反序列化*/
        ByteArrayInputStream input1 = new ByteArrayInputStream(buffer.toByteArray());
        try (ObjectInputStream input2 = new ObjectInputStream(input1)) {
            int n1 = input2.readInt();
            String s1 = input2.readUTF();
            Double d1 = (Double) input2.readObject();
            System.out.println(n1+s1+d1);
        }


        /**Reader 字符流*/
        //FileReader
        try (Reader reader = new FileReader("test/test.txt")) {
            char[] buffer1 = new char[1000];
            int n;
            while ((n = reader.read(buffer1)) != -1) {
                System.out.println("read " + n + " chars.");
            }
        }
        //CharArrayReader 模拟Reader
        try (Reader reader = new CharArrayReader("Hello".toCharArray())) {
            System.out.println(reader);
        }
        //StringReader
        try (Reader reader = new StringReader("Hello")) {
            System.out.println(reader);
        }
        //InputStreamReader
        try (Reader reader = new InputStreamReader(new FileInputStream("test/test.txt"), "UTF-8")) {
            // TODO:
            System.out.println(reader);
        }

        /**Wirter 字符流*/
        //FileWriter
        try (Writer writer = new FileWriter("test/test.txt")) {
            writer.write('H'); // 写入单个字符
            writer.write("Hello".toCharArray()); // 写入char[]
            writer.write("Hello"); // 写入String
            writer.write("你好");
        }

        //CharArrayWriter
        try (CharArrayWriter writer = new CharArrayWriter()) {
            writer.write(65);
            writer.write(66);
            writer.write(67);
            char[] data4 = writer.toCharArray(); // { 'A', 'B', 'C' }
            System.out.println(data4);
        }

        //StringWriter
        //OutputStreamWriter
        try (Writer writer = new OutputStreamWriter(new FileOutputStream("test/test.txt"), "UTF-8")) {
            // TODO:
            System.out.println(writer);
        }

        /**PrintStream和PrintWriter*/
        System.out.print(12345); // 输出12345
        System.out.print(new Object()); // 输出类似java.lang.Object@3c7a835a
        System.out.println("Hello"); // 输出Hello并换行

        StringWriter buffer4 = new StringWriter();
        try (PrintWriter pw = new PrintWriter(buffer4)) {
            pw.println("Hello");
            pw.println(12345);
            pw.println(true);
        }
        System.out.println(buffer4.toString());

    }
}