java，io流

java里面的io流是操作文件读写的一门技术。

I：in 指的是输入流，读取文件内容到流对象

O：out 指的是输出流，写文件内容到流对象

流指的是对象。

字节流常用api:

copy文件的dome如下：

package com.mg.java.maven.day01;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * io流
 * 
 * @author admin
 *
 */
public class FileCopy {
    public static void main(String[] args) throws IOException {
        String filepath = "C:\Users\admin\Desktop\装饰器.png";
        String topath = "C:\Users\admin\Desktop\装饰器2.png";
        FileCopy file = new FileCopy();
        file.fileCopy(filepath, topath);
//        fileCopy(filepath, topath);
    }

    public void fileCopy(String filepath, String topath) throws FileNotFoundException, IOException {
        InputStream inputStream = new FileInputStream(new File(filepath));
        OutputStream outputStream = new FileOutputStream(new File(topath));
        int size = 0;
        while ((size = inputStream.read()) != -1) {
            outputStream.write(size);
        }
        if (inputStream != null) {
            inputStream.close();
        }
        if (outputStream != null) {
            outputStream.close();
        }
        System.out.println("success");
    }
}

静态方法调用不需要创建对象

package com.mg.java.maven.day01;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * io流
 * 
 * @author admin
 *
 */
public class FileCopy02 {
    public static void main(String[] args) throws IOException {
        String filepath = "C:\Users\admin\Desktop\装饰器.png";
        String topath = "C:\Users\admin\Desktop\装饰器2.png";
        FileCopy02.fileCopy("C:\Users\admin\Desktop\装饰器.png", "C:\Users\admin\Desktop\装饰器2.png");
    }

    public static void fileCopy(String filepath, String topath) throws FileNotFoundException, IOException {
        InputStream inputStream = new FileInputStream(new File(filepath));
        OutputStream outputStream = new FileOutputStream(new File(topath));
        int size = 0;
        while ((size = inputStream.read()) != -1) {
            outputStream.write(size);
        }
        if (inputStream != null) {
            inputStream.close();
        }
        if (outputStream != null) {
            outputStream.close();
        }
        System.out.println("success");
    }
}