Java代码生成图片验证码

1.jsp页面显示验证码，src跳转到controller里的：getimg_validate，reloadimg()作用是点击验证码就会换一张（重新请求getimg_validate）

<ul>
<li >验证码： </li>
<li >
<img id="img_validate" src="<%=basepath%>image/getimg_validate" onclick="reloadimg()">
<input type="text" name="yanzhengma" id="yanzhengma" placeholder="请输入验证码"/>
</li>
</ul>

<script type="text/javascript">

function reloadimg() {

document.getelementbyid("img_validate").src="<%=basepath%>image/getimg_validate";
}

</script>

2.写一个imageutil工具类，在里面可以自定义图片生成的大小，字体大小，背景色，验证码个数，干扰线条条数等等

package com.svse.house.util;

import java.awt.color;
import java.awt.font;
import java.awt.graphics;
import java.awt.image.bufferedimage;
import java.util.random;

public class imageutil {

//1.定义变量保存生成后的验证码字符串
static string code = "";

//2.生成验证码
public static string createcode() {
code = "";
string a = "0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";//随机生成的字符范围(0-9,a-z,a-z)

//生成验证码的位数(这里是4位)
for (int i = 0; i < 4; i++) {
int index = (int) (math.random() * 62);//会产生一个[0,62)的数，不包含小数
char b = a.charat(index);
code = code + b;
}
return code;
}

//查看已经生成的验证码
public static string getcode() {
return code;
}

//3.生成图片
public static bufferedimage createimage() {
// 前2个参数为：width, height.后面是图像类型
//创建一个不带透明色的bufferedimage对象,type_int_argb为带透明色
bufferedimage bi = new bufferedimage(130,50, bufferedimage.type_int_rgb);

//1.得到一个画布
graphics g = bi.getgraphics();
//2.添加背景颜色
g.setcolor(color.white);
g.fillrect(0, 0, 130, 50);

//3.添加干扰线
for (int i = 0; i < 10; i++) {
random r = new random();
int red = r.nextint(256);
int green = r.nextint(256);
int blue = r.nextint(256);
color c = new color(red, green, blue);
g.setcolor(c);
int x1 = r.nextint(131);
int y1 = r.nextint(51);
int x2 = r.nextint(131);
int y2 = r.nextint(51);
g.drawline(x1,y1,x2,y2);//画线
//g.drawoval(x1, y1, x2, y2);//画曲线
}

//3.添加文字
g.setcolor(color.black);
g.setfont(new font("宋体", font.bold, 50));

string str = getcode();
//4.将文字填充到画板中
g.drawstring(str, 15, 40);

//5.关闭画布
g.dispose();
return bi;
}

}

3.在controller层调用getimg_validate，试用过jpeg和bmp格式的setcontenttype，都可以

package com.svse.house.controller;

import java.awt.image.bufferedimage;
import java.io.bytearrayoutputstream;
import java.io.ioexception;

import javax.imageio.imageio;
import javax.servlet.servletoutputstream;
import javax.servlet.http.httpservletresponse;

import org.springframework.stereotype.controller;
import org.springframework.web.bind.annotation.requestmapping;

import com.svse.house.util.imageutil;

@controller
@requestmapping("/image")
public class imagecontroller {
@requestmapping("/getimg_validate")
public void yanzheng(httpservletresponse response){
try {
imageutil.createcode();
bufferedimage image = imageutil.createimage();
//以流的方式返回给客户端
response.setcontenttype("image/jpeg");
//response.setcontenttype("image/bmp");
bytearrayoutputstream bt = new bytearrayoutputstream();
//将图片转换成字节流
imageio.write(image,"jpeg",bt);
//imageio.write(image,"bmp",bt);
//得到输出流，返回客户端
servletoutputstream outputstream = response.getoutputstream();
outputstream.write(bt.tobytearray());
} catch (ioexception e) {
e.printstacktrace();
}
}
}