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;
public class CaptchaGenerator {
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'
};
final private String[] fontNames = new String[]{
"黑体", "宋体", "Courier", "Arial",
"Verdana", "Times", "Tahoma", "Georgia"};
final private int[] fontStyles = new int[]{
Font.BOLD, Font.ITALIC|Font.BOLD
};
private int vcodeLen = 4;
private int fontsize = 21;
private int width = (fontsize+1)*vcodeLen+10;
private int height = fontsize+12;
private int disturbline = 3;
public CaptchaGenerator(){}
public CaptchaGenerator(int vcodeLen) {
this.vcodeLen = vcodeLen;
this.width = (fontsize+1)*vcodeLen+10;
}
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;
}
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;
}
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();
}
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);
}
}
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;
}
private Color getRandomColor(){
Random ran = new Random();
return new Color(ran.nextInt(220), ran.nextInt(220), ran.nextInt(220));
}
private double getTheta(){
return ((int) (Math.random()*1000) % 2 == 0 ? -1 : 1)*Math.random();
}
public int getVcodeLen() {
return vcodeLen;
}
public void setVcodeLen(int vcodeLen) {
this.width = (fontsize+3)*vcodeLen+10;
this.vcodeLen = vcodeLen;
}
public int getFontsize() {
return fontsize;
}
public void setFontsize(int fontsize) {
this.width = (fontsize+3)*vcodeLen+10;
this.height = fontsize+15;
this.fontsize = fontsize;
}
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
public int getDisturbline() {
return 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"%>Insert title here
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考高分网。
