如果给前端返回图片，以验证码为例
最近做项目，遇到给前端返回验证码。 第一次做的时候，直接以流的形式返回：
1.生成验证码的图片：
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;
import java.util.Random;
/**
* 验证码生成器
*
* @author
*/
public class VerificationCodeImgUtil {
// 图片的宽度。
private int width = 160;
// 图片的高度。
private int height = 40;
// 验证码字符个数
private int codeCount = 5;
// 验证码干扰线数
private int lineCount = 150;
// 验证码
private String code = null;
// 验证码图片Buffer
private BufferedImage buffImg = null;
// 验证码范围,去掉0(数字)和O(拼音)容易混淆的(小写的1和L也可以去掉,大写不用了)
private char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R',
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
/**
* 默认构造函数,设置默认参数
*/
public VerificationCodeImgUtil() {
this.createCode();
}
/**
* @param width
* 图片宽
* @param height
* 图片高
*/
public VerificationCodeImgUtil(int width, int height) {
this.width = width;
this.height = height;
this.createCode();
}
/**
* @param width
* 图片宽
* @param height
* 图片高
* @param codeCount
* 字符个数
* @param lineCount
* 干扰线条数
*/
public VerificationCodeImgUtil(int width, int height, int codeCount, int lineCount) {
this.width = width;
this.height = height;
this.codeCount = codeCount;
this.lineCount = lineCount;
this.createCode();
}
public void createCode() {
int x = 0, fontHeight = 0, codeY = 0;
int red = 0, green = 0, blue = 0;
x = width / (codeCount + 2);// 每个字符的宽度(左右各空出一个字符)
fontHeight = height - 2;// 字体的高度
codeY = height - 4;
// 图像buffer
buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
// 生成随机数
Random random = new Random();
// 将图像填充为白色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
// 创建字体,可以修改为其它的
Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
// Font font = new Font("Times New Roman", Font.ROMAN_BASELINE, fontHeight);
g.setFont(font);
for (int i = 0; i < lineCount; i++) {
// 设置随机开始和结束坐标
int xs = random.nextInt(width);// x坐标开始
int ys = random.nextInt(height);// y坐标开始
int xe = xs + random.nextInt(width / 8);// x坐标结束
int ye = ys + random.nextInt(height / 8);// y坐标结束
// 产生随机的颜色值，让输出的每个干扰线的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
g.setColor(new Color(red, green, blue));
g.drawLine(xs, ys, xe, ye);
}
// randomCode记录随机产生的验证码
StringBuffer randomCode = new StringBuffer();
// 随机产生codeCount个字符的验证码。
for (int i = 0; i < codeCount; i++) {
String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
// 产生随机的颜色值，让输出的每个字符的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
g.setColor(new Color(red, green, blue));
g.drawString(strRand, (i + 1) * x, codeY);
// 将产生的四个随机数组合在一起。
randomCode.append(strRand);
}
// 将四位数字的验证码保存到Session中。
code = randomCode.toString();
}
public void write(String path) throws IOException {
OutputStream sos = new FileOutputStream(path);
this.write(sos);
}
public void write(OutputStream sos) throws IOException {
ImageIO.write(buffImg, "png", sos);
sos.close();
}
public BufferedImage getBuffImg() {
return buffImg;
}
public String getCode() {
return code;
}
/**
* 测试函数,默认生成到d盘
*
* @param args
*/
public static void main(String[] args) {
VerificationCodeImgUtil vCode = new VerificationCodeImgUtil(160, 40, 5, 150);
try {
String path = "D:/" + new Date().getTime() + ".png";
System.out.println(vCode.getCode() + " >" + path);
vCode.write(path);
} catch (IOException e) {
e.printStackTrace();
}
}
}
2.调用接口返回验证码的流
/**
* @Title: validateCode
* @Description: (响应验证码页面 )
* @param @param request
* @param @param response
* @param @return
* @param @throws Exception 设定文件
* @return String 返回类型
* @throws
*/
@RequestMapping(value="/validateCode")
public String validateCode(HttpServletRequest request,HttpServletResponse response) throws Exception{
// 设置响应的类型格式为图片格式
response.setContentType("image/jpeg");
//禁止图像缓存。
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
HttpSession session = request.getSession();
VerificationCodeImgUtil vCode = new VerificationCodeImgUtil(120,40,5,100);
session.setAttribute("code", vCode.getCode());
vCode.write(response.getOutputStream());
return null;
}
3.返回的输出流，因此，前端只需直接展示：
但是前端说，他们不想这么做，只想要加密的base64的字符串。因此我这边稍作修改：
修改后的完成代码：
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Random;
/**
* 验证码生成器
*
* @author
*/
public class ImageValidateCode {
// 图片的宽度。
private int width = 160;
// 图片的高度。
private int height = 40;
// 验证码字符个数
private int codeCount = 5;
// 验证码干扰线数
private int lineCount = 150;
// 验证码
private String code = null;
// 验证码图片Buffer
private BufferedImage buffImg = null;
// 验证码范围,去掉0(数字)和O(拼音)容易混淆的(小写的1和L也可以去掉,大写不用了)
private char[] codeSequence = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z','A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
/**
* 默认构造函数,设置默认参数
*/
public ImageValidateCode() {
this.createCode();
}
/**
* @param width 图片宽
* @param height 图片高
*/
public ImageValidateCode(int width, int height) {
this.width = width;
this.height = height;
this.createCode();
}
/**
* @param width 图片宽
* @param height 图片高
* @param codeCount 字符个数
* @param lineCount 干扰线条数
*/
public ImageValidateCode(int width, int height, int codeCount, int lineCount) {
this.width = width;
this.height = height;
this.codeCount = codeCount;
this.lineCount = lineCount;
this.createCode();
}
public void createCode() {
int x = 0, fontHeight = 0, codeY = 0;
int red = 0, green = 0, blue = 0;
x = width / (codeCount + 2);//每个字符的宽度(左右各空出一个字符)
fontHeight = height - 2;//字体的高度
codeY = height - 4;
// 图像buffer
buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
// 生成随机数
Random random = new Random();
// 将图像填充为白色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
// 创建字体,可以修改为其它的
Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
// Font font = new Font("Times New Roman", Font.ROMAN_BASELINE, fontHeight);
g.setFont(font);
for (int i = 0; i < lineCount; i++) {
// 设置随机开始和结束坐标
int xs = random.nextInt(width);//x坐标开始
int ys = random.nextInt(height);//y坐标开始
int xe = xs + random.nextInt(width / 8);//x坐标结束
int ye = ys + random.nextInt(height / 8);//y坐标结束
// 产生随机的颜色值，让输出的每个干扰线的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
g.setColor(new Color(red, green, blue));
g.drawLine(xs, ys, xe, ye);
}
// randomCode记录随机产生的验证码
StringBuffer randomCode = new StringBuffer();
// 随机产生codeCount个字符的验证码。
for (int i = 0; i < codeCount; i++) {
String strRand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
// 产生随机的颜色值，让输出的每个字符的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
g.setColor(new Color(red, green, blue));
g.drawString(strRand, (i + 1) * x, codeY);
// 将产生的四个随机数组合在一起。
randomCode.append(strRand);
}
// 将四位数字的验证码保存到Session中。
code = randomCode.toString();
}
public void write(String path) throws IOException {
OutputStream sos = new FileOutputStream(path);
this.write(sos);
}
public void write(OutputStream sos) throws IOException {
ImageIO.write(buffImg, "png", sos);
sos.close();
}
public BufferedImage getBuffImg() {
return buffImg;
}
public String getCode() {
return code;
}
public InputStream getImageStream(BufferedImage bimage) {
InputStream is = null;
ByteArrayOutputStream bs = new ByteArrayOutputStream();
ImageOutputStream imOut;
try {
imOut = ImageIO.createImageOutputStream(bs);
ImageIO.write(bimage, "png", imOut);
is = new ByteArrayInputStream(bs.toByteArray());
} catch (IOException e) {
e.printStackTrace();
}
return is;
}
} /**
* 响应验证码页面
* @return
*/
@GetMapping(value="/imageValidateCode")
public String validateCode() throws Exception{
HttpSession session = request.getSession();
ImageValidateCode vCode = new ImageValidateCode();
session.setAttribute("code", vCode.getCode());
InputStream io = vCode.getImageStream(vCode.getBuffImg());
byte [] data = new byte[io.available()];
io.read(data);
io.close();
// 加密
return new String(Base64.getEncoder().encode(data));
}验证：
public static void main(String[] args) {
byte [] bs = Base64.getDecoder().decode("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");
String path = "D:/" + new Date().getTime() + ".png";
try {
OutputStream oStream = new FileOutputStream(path);
oStream.write(bs);
oStream.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}前端展示：略。