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java将图片转为base64返回给前端

2020年02月18日 编程语言 ⁄ 共 6369字 ⁄ 字号 评论关闭

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"%><!DOCTYPE html><html><head><meta charset="ISO-8859-1"><title>Insert title here</title><script src="../static/model/js/jquery-1.11.2.min.js"></script></head><body> <img id="randomImage" src="" /> <script type="text/javascript"> $(function() { refreshimg(); }) function refreshimg() { $.ajax({ type : "POST", dataType : "json", url : "../article/captcha", success : function(data) { console.log('base64=' + data.codePic); $('#randomImage').attr('src', data.code); }, error : function() { } }); $("#randomImage").click(refreshimg) } </script></body></html>

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持我们。

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