package com.demo.zmz;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.BufferedWriter;import java.io.ByteArrayOutputStream;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.FileWriter;import java.io.IOException;import java.util.Base64;public class Base64Test {	public static void main(String[] args) {				// 编码		encodeBase64();					// 解码			dcodeBase64();	}	private static void dcodeBase64() {		// TODO Auto-generated method stub		try (BufferedInputStream in = new BufferedInputStream(new FileInputStream("a.txt"));				BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream("aa.jpg"))) {			// RTFM 			//内存数组，输出流，写入buf用			ByteArrayOutputStream ramArray = new ByteArrayOutputStream();						byte[] buf = new byte[1024*4];			int size;			while (-1 != (size = in.read(buf))) {				ramArray.write(buf, 0, size);			}			// 获得所有数据			byte[] data = ramArray.toByteArray();			//获取编码器-->返回字符串			byte[] img = Base64.getDecoder().decode(data);						out.write(img);			System.out.println("ok");					} catch (IOException e) {					}	}		private static void encodeBase64() {				try (BufferedInputStream in = new BufferedInputStream(new FileInputStream("11111.jpg"));				BufferedWriter out = new BufferedWriter(new FileWriter("a.txt"))) {			// RTFM 			//内存数组，输出流，写入buf用			ByteArrayOutputStream ramArray = new ByteArrayOutputStream();						byte[] buf = new byte[1024*4];			int size;			while (-1 != (size = in.read(buf))) {				ramArray.write(buf, 0, size);			}			// 获得所有数据			byte[] data = ramArray.toByteArray();			//获取编码器-->返回字符串			String s = Base64.getEncoder().encodeToString(data);			System.out.println(s);						out.write(s);					} catch (IOException e) {					}	}}

inputstream和outputstream是字节流，writer和reader是字符流