java实现后台返回base64图形编码
作者：樊皓白
这篇文章主要介绍了java实现后台返回base64图形编码，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教
java后台返回base64图形编码
工具类
package com.liginfo.app.util;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Random;
import javax.imageio.ImageIO;
import org.apache.tomcat.util.codec.binary.Base64;
import sun.misc.BASE64Encoder;
/*
* 返回base64验证码的工具类
*/
public class RandomGraphic {
// 默认验证码6位
private static int DEFAULT_CODE_NUMBERS = 6;
private static Random random = new SecureRandom();
public static String generateCode(){
StringBuffer sb = new StringBuffer();
for (int i = 0; i< DEFAULT_CODE_NUMBERS; i++){
sb.append(random.nextInt(10));
}
return sb.toString();
}
public static String generateCode(int numbers){
StringBuffer sb = new StringBuffer();
for (int i = 0; i< numbers; i++){
sb.append(random.nextInt(10));
}
return sb.toString();
}
/**
* 使用系统默认字符源生成验证码
*
* @param verifySize
* 验证码长度
* @return
*/
public static String generateVerifyCode(int verifySize) {
return generateVerifyCode(verifySize, VERIFY_CODES);
}
/**
* 使用指定源生成验证码
*
* @param verifySize
* 验证码长度
* @param sources
* 验证码字符源
* @return
*/
public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
public static String generateVerifyCode(int verifySize, String sources) {
if (sources == null || sources.length() == 0) {
sources = VERIFY_CODES;
}
int codesLen = sources.length();
Random rand = new Random(System.currentTimeMillis());
StringBuilder verifyCode = new StringBuilder(verifySize);
for (int i = 0; i < verifySize; i++) {
verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
}
return verifyCode.toString();
}
/**
* 输出指定验证码图片流
*
* @param w
* @param h
* @param code
* @throws IOException
*/
public static String outputImage(int w, int h, String code) throws IOException {
int verifySize = code.length();
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Random rand = new Random();
Graphics2D g2 = image.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Color[] colors = new Color[5];
Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN, Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE, Color.PINK, Color.YELLOW };
float[] fractions = new float[colors.length];
for (int i = 0; i < colors.length; i++) {
colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
fractions[i] = rand.nextFloat();
}
Arrays.sort(fractions);
g2.setColor(Color.GRAY);// 设置边框色
g2.fillRect(0, 0, w, h);
Color c = getRandColor(200, 250);
g2.setColor(c);// 设置背景色
g2.fillRect(0, 2, w, h - 4);
// 绘制干扰线
Random random = new Random();
g2.setColor(getRandColor(160, 200));// 设置线条的颜色
for (int i = 0; i < 20; i++) {
int x = random.nextInt(w - 1);
int y = random.nextInt(h - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g2.drawLine(x, y, x + xl + 40, y + yl + 20);
}
// 添加噪点
float yawpRate = 0.05f;// 噪声率
int area = (int) (yawpRate * w * h);
for (int i = 0; i < area; i++) {
int x = random.nextInt(w);
int y = random.nextInt(h);
int rgb = getRandomIntColor();
image.setRGB(x, y, rgb);
}
shear(g2, w, h, c);// 使图片扭曲
g2.setColor(getRandColor(100, 160));
int fontSize = h - 4;
Font font = new Font("Algerian", Font.ITALIC, fontSize);
g2.setFont(font);
char[] chars = code.toCharArray();
for (int i = 0; i < verifySize; i++) {
AffineTransform affine = new AffineTransform();
affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);
g2.setTransform(affine);
g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
}
g2.dispose();
String result = null;
ByteArrayOutputStream out = new ByteArrayOutputStream();
boolean flag = ImageIO.write(image, "GIF", out);
byte[] b = out.toByteArray();
BASE64Encoder base64Encoder = new BASE64Encoder();
// result = base64Encoder.encode(b);
result = Base64.encodeBase64String(b);
return result;
}
private static Color getRandColor(int fc, int bc) {
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
private static int getRandomIntColor() {
int[] rgb = getRandomRgb();
int color = 0;
for (int c : rgb) {
color = color << 8;
color = color | c;
}
return color;
}
private static int[] getRandomRgb() {
int[] rgb = new int[3];
for (int i = 0; i < 3; i++) {
rgb[i] = random.nextInt(255);
}
return rgb;
}
private static void shear(Graphics g, int w1, int h1, Color color) {
shearX(g, w1, h1, color);
shearY(g, w1, h1, color);
}
private static void shearX(Graphics g, int w1, int h1, Color color) {
int period = random.nextInt(2);
boolean borderGap = true;
int frames = 1;
int phase = random.nextInt(2);
for (int i = 0; i < h1; i++) {
double d = (double) (period >> 1) * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
g.copyArea(0, i, w1, 1, (int) d, 0);
if (borderGap) {
g.setColor(color);
g.drawLine((int) d, i, 0, i);
g.drawLine((int) d + w1, i, w1, i);
}
}
}
private static void shearY(Graphics g, int w1, int h1, Color color) {
int period = random.nextInt(40) + 10; // 50;
boolean borderGap = true;
int frames = 20;
int phase = 7;
for (int i = 0; i < w1; i++) {
double d = (double) (period >> 1) * Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
g.copyArea(i, 0, 1, h1, 0, (int) d);
if (borderGap) {
g.setColor(color);
g.drawLine(i, (int) d, i, 0);
g.drawLine(i, (int) d + h1, i, h1);
}
}
}
public static void main(String arg[]){
for (int i =0;i<2000;i++){
String s = RandomGraphic.generateCode();
System.out.println(s);
}
}
}
使用方法
String code = RandomGraphic.generateVerifyCode(4);
String data = "";
try {
data = RandomGraphic.outputImage(100,30,code);
j.setAttributes(map);
} catch (IOException e) {
j.setSuccess(false);
j.setMsg("获取验证码失败");
// TODO Auto-generated catch block
e.printStackTrace();
}后端返回base64验证码,解析不出来
注意下base64的验证码，有类似data:image/jpg;base64这种前缀，后面才是具体字符串，所以要么后端拼接上前缀，要么前端，才能解析出来。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。