图片转化成二进制，保存文件。再转化为图片

package com.company;

import java.awt.image.BufferedImage;
import java.io.*;

import javax.imageio.ImageIO;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class TestImageBinary {
    static BASE64Encoder encoder = new sun.misc.BASE64Encoder();
    static BASE64Decoder decoder = new sun.misc.BASE64Decoder();

    public static void main(String[] args) throws IOException{
        //System.out.println(getImageBinary());
       // saveAsFileWriter(getImageBinary());

       // base64StringToImage(getImageBinary());
        String path = "./test.txt";
        base64StringToImage(read_binaryfile(path));


    }

    static String getImageBinary(){
        File f = new File("./screen.png");
        BufferedImage bi;
        try {
            bi = ImageIO.read(f);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ImageIO.write(bi, "png", baos);
            byte[] bytes = baos.toByteArray();

            return encoder.encodeBuffer(bytes).trim();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    static void base64StringToImage(String base64String){
        try {
            byte[] bytes1 = decoder.decodeBuffer(base64String);

            ByteArrayInputStream bais = new ByteArrayInputStream(bytes1);
            BufferedImage bi1 =ImageIO.read(bais);
            File w2 = new File("./QQ.png");//可以是jpg,png,gif格式
            ImageIO.write(bi1, "png", w2);//不管输出什么格式图片，此处不需改动
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static   String savefile = "./test.txt";
    private static void saveAsFileWriter(String content) {

        FileWriter fwriter = null;
        try {
            fwriter = new FileWriter(savefile);
            fwriter.write(content);
        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            try {
                fwriter.flush();
                fwriter.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

    private  static  String read_binaryfile(String path) throws IOException{
        InputStream inputStream  = new FileInputStream(path);
        BufferedReader in = new BufferedReader(new InputStreamReader(inputStream));
        StringBuffer buffer = new StringBuffer();
        String line = "";
        while((line =in.readLine()) !=null){
            buffer.append(line);
        }
        return buffer.toString();

    }



}