IO流参考

1

import java.io.File;
import java.io.FileInputStream;

/**
 * 读取一个字符
 */
public class MyReadChar {
    public static void main(String[] args) {
        try {
            File f = new File("D:\\labs\\test.txt");

            FileInputStream fis = new FileInputStream(f);

            System.out.println((char)fis.read());
        } catch (Exception e) {

        }
    }
}

2

import java.io.File;
import java.io.FileInputStream;

public class MyReadFile {
    public static void main(String[] args) {
        try {
            File f = new File("D:\\labs\\test.txt");

            FileInputStream fis = new FileInputStream(f);

            int length = fis.available();
            for (int i = 0; i <length; ++i) {
                System.out.print((char)fis.read());
            }
        } catch (Exception e) {

        }
    }
}

3

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

public class MyCopyFile {
    public static void main(String[] args) {
        try {
            File in = new File("D:\\labs\\test.txt");
            File out = new File("D:\\labs\\another_test.txt");

            FileInputStream fis = new FileInputStream(in);
            FileOutputStream fos = new FileOutputStream(out);

            int length = fis.available();
            for (int i = 0; i < length; ++i) {
                fos.write(fis.read());
            }
        } catch (Exception e) {

        }
    }
}

4

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

public class MyCopyBigFile {
    public static void main(String[] args) {
        try {
            File in = new File("D:\\labs\\test.txt");
            File out = new File("D:\\labs\\another_test.txt");

            FileInputStream fis = new FileInputStream(in);
            FileOutputStream fos = new FileOutputStream(out);

            byte[] tmp = new byte[8192];
            // 处理大部分内容
            int length = fis.available()/8192;
            for (int i = 0; i < length; ++i) {
                fis.read(tmp);
                fos.write(tmp);
            }
            int size = fis.read(tmp);
            fos.write(tmp, 0, size);
        } catch (Exception e) {
        }
    }
}

5

import java.io.File;
import java.io.FileOutputStream;

public class MyKey {
    public static void main(String[] args) {
        try {
            File f = new File("D:\\labs\\key.key");

            FileOutputStream fos = new FileOutputStream(f);

            for (int i = 0; i < 128; ++i) {
                fos.write((int)(Math.random()*128));
            }
        } catch (Exception e) {

        }
    }
}

6

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

public class MyEncryp {
    public static void main(String[] args) {
        try {
            int key[] = new int[128];
            File keyFile = new File("D:\\labs\\key.key");

            FileInputStream keyFis = new FileInputStream(keyFile);

            for (int i = 0; i < 128; ++i) {
                key[i] = keyFis.read();
            }

            File in = new File("D:\\labs\\test.txt");
            File out = new File("D:\\labs\\another_test.txt");

            FileInputStream fis = new FileInputStream(in);
            FileOutputStream fos = new FileOutputStream(out);

            int length = fis.available();
            for (int i = 0; i < length; ++i) {
                fos.write(fis.read() + key[i%128]);
            }
        } catch (Exception e) {}
    }
}