java将图片转为base64返回给前端

java将图片转为base64返回给前端

本文实例为大家分享了java将图片转为base64返回给前端的具体代码，供大家参考，具体内容如下

一、controller端代码

@RequestMapping(value = "/captcha")

public void imagecode(HttpServletRequest request, HttpServletResponse response) throws Exception {

jsONObject object = new JSONObject();

CaptchaGenerator vcg = new CaptchaGenerator();

String vcode = vcg.generatorVCode();

BufferedImage vcodeImage = vcg.generatorVCodeImage(vcode, true);

response.setDateHeader("Expires", 0);

response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");

response.addHeader("Cache-Control", "post-check=0, pre-check=0");

response.setHeader("Pragma", "no-cache");

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

response.addHeader("code", vcode.toLowerCase());

try {

ImageIO.write(vcodeImage, "png", outputStream);

BASE64Encoder encoder = new BASE64Encoder();

String base64 = encoder.encodeBuffer(outputStream.toByteArray()).trim();

base64 = base64.replaceAll("\n", "").replaceAll("\r", "");

object.put("code", "data:image/jpg;base64," + base64);

response.getWriter().write(object.toString());

} catch (IOException e) {

response.getWriter().write("");

} finally {

if (outputStream != null) {

outputStream.flush();

outputStream.close();

response.getWriter().close();

}

}

}

二、生成验证码的代码

（从某博客拷过来直接用的）

package com.kinth.security.web.util;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.util.Random;

/**

* 验证码生成器

*

*

*/

public class CaptchaGenerator {

/**

* 验证码来源

*/

final private char[] code = {

'2', '3', '4', '5', '6', '7', '8', '9',

'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',

'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v',

'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F',

'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R',

'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'

};

/**

* 字体

*/

final private String[] fontNames = new String[]{

"黑体", "宋体", "Courier", "Arial",

"Verdana", "Times", "Tahoma", "Georgia"};

/**

* 字体样式

*/

final private int[] fontStyles = new int[]{

Font.BOLD, Font.ITALIC|Font.BOLD

};

/**

* 验证码长度

* 默认4个字符

*/

private int vcodeLen = 4;

/**

* 验证码图片字体大小

* 默认17

*/

private int fontsize = 21;

/**

* 验证码图片宽度

*/

private int width = (fontsize+1)*vcodeLen+10;

/**

* 验证码图片高度

*/

private int height = fontsize+12;

/**

* 干扰线条数

* 默认3条

*/

private int disturbline = 3;

public CaptchaGenerator(){}

/**

* 指定验证码长度

* @param vcodeLen 验证码长度

*/

public CaptchaGenerator(int vcodeLen) {

this.vcodeLen = vcodeLen;

this.width = (fontsize+1)*vcodeLen+10;

}

/**

* 生成验证码图片

* @param vcode 要画的验证码

* @param drawline 是否画干扰线

* @return

*/

public BufferedImage generatorVCodeImage(String vcode, boolean drawline){

//创建验证码图片

BufferedImage vcodeImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics g = vcodeImage.getGraphics();

//填充背景色

g.setColor(new Color(246, 240, 250));

g.fillRect(0, 0, width, height);

if(drawline){

drawDisturbLine(g);

}

//用于生成伪随机数

Random ran = new Random();

//在图片上画验证码

for(int i = 0;i < vcode.length();i++){

//设置字体

g.setFont(new Font(fontNames[ran.nextInt(fontNames.length)], fontStyles[ran.nextInt(fontStyles.length)], fontsize));

//随机生成颜色

g.setColor(getRandomColor());

//画验证码

g.drawString(vcode.charAt(i)+"", i*fontsize+10, fontsize+5);

}

//释放此图形的上下文以及它使用的所有系统资源

g.dispose();

return vcodeImage;

}

/**

* 获得旋转字体的验证码图片

* @param vcode

* @param drawline 是否画干扰线

* @return

*/

public BufferedImage generatorRotateVCodeImage(String vcode, boolean drawline){

//创建验证码图片

BufferedImage rotateVcodeImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics2D g2d = rotateVcodeImage.createGraphics();

//填充背景色

g2d.setColor(new Color(246, 240, 250));

g2d.fillRect(0, 0, width, height);

if(drawline){

drawDisturbLine(g2d);

}

//在图片上画验证码

for(int i = 0;i < vcode.length();i++){

BufferedImage rotateImage = getRotateImage(vcode.charAt(i));

g2d.drawImage(rotateImage, null, (int) (this.height * 0.7) * i, 0);

}

g2d.dispose();

return rotateVcodeImage;

}

/**

* 生成验证码

* @return 验证码

*/

public String generatorVCode(){

int len = code.length;

Random ran = new Random();

StringBuffer sb = new StringBuffer();

for(int i = 0;i < vcodeLen;i++){

int index = ran.nextInt(len);

sb.append(code[index]);

}

return sb.toString();

}

/**

* 为验证码图片画一些干扰线

* @param g

*/

private void drawDisturbLine(Graphics g){

Random ran = new Random();

for(int i = 0;i < disturbline;i++){

int x1 = ran.nextInt(width);

int y1 = ran.nextInt(height);

int x2 = ran.nextInt(width);

int y2 = ran.nextInt(height);

g.setColor(getRandomColor());

//画干扰线

g.drawLine(x1, y1, x2, y2);

}

}

/**

* 获取一张旋转的图片

* @param c 要画的字符

* @return

*/

private BufferedImage getRotateImage(char c){

BufferedImage rotateImage = new BufferedImage(height, height, BufferedImage.TYPE_INT_ARGB);

Graphics2D g2d = rotateImage.createGraphics();

//设置透明度为0

g2d.setColor(new Color(255, 255, 255, 0));

g2d.fillRect(0, 0, height, height);

Random ran = new Random();

g2d.setFont(new Font(fontNames[ran.nextInt(fontNames.length)], fontStyles[ran.nextInt(fontStyles.length)], fontsize));

g2d.setColor(getRandomColor());

double theta = getTheta();

//旋转图片

g2d.rotate(theta, height/2, height/2);

g2d.drawString(Character.toString(c), (height-fontsize)/2, fontsize+5);

g2d.dispose();

return rotateImage;

}

/**

* @return 返回一个随机颜色

*/

private Color getRandomColor(){

Random ran = new Random();

return new Color(ran.nextInt(220), ran.nextInt(220), ran.nextInt(220));

}

/**

* @return 角度

*/

private double getTheta(){

return ((int) (Math.random()*1000) % 2 == 0 ? -1 : 1)*Math.random();

}

/**

* @return 验证码字符个数

*/

public int getVcodeLen() {

return vcodeLen;

}

/**

* 设置验证码字符个数

* @param vcodeLen

*/

public void setVcodeLen(int vcodeLen) {

this.width = (fontsize+3)*vcodeLen+10;

this.vcodeLen = vcodeLen;

}

/**

* @return 字体大小

*/

public int getFontsize() {

return fontsize;

}

/**

* 设置字体大小

* @param fontsize

*/

public void setFontsize(int fontsize) {

this.width = (fontsize+3)*vcodeLen+10;

this.height = fontsize+15;

this.fontsize = fontsize;

}

/**

* @return 图片宽度

*/

public int getWidth() {

return width;

}

/**

* 设置图片宽度

* @param width

*/

public void setWidth(int width) {

this.width = width;

}

/**

* @return 图片高度

*/

public int getHeight() {

return height;

}

/**

* 设置图片高度

* @param height

*/

public void setHeight(int height) {

this.height = height;

}

/**

* @return 干扰线条数

*/

public int getDisturbline() {

return disturbline;

}

/**

* 设置干扰线条数

* @param disturbline

*/

public void setDisturbline(int disturbline) {

this.disturbline = disturbline;

}

}

三、前端显示

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

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