linux下图形验证码显示问题

发现很多人问这个问题，我也是从网上搜到的答案。在这里和大家共享一下：

解决方案1:

在java启动参数中增加-Djava.awt.headless=true 就可以了。以tomcat为例，就是在tomcat的bin目录下找到catalina.sh。打开后可以看到有很多-D的地方就是启动参数了。在所有的分支中都加上-Djava.awt.headless=true就可以了。下面是一段catalina.sh的例子代码：

-Djava.endorsed.dirs="$JAVA_ENDORSED_DIRS" -classpath "$CLASSPATH" \

-sourcepath "$CATALINA_HOME"/../../jakarta-tomcat-catalina/catalina/src/share \

-Djava.security.manager \

-Djava.security.policy=="$CATALINA_BASE"/conf/catalina.policy \

-Dcatalina.base="$CATALINA_BASE" \

-Dcatalina.home="$CATALINA_HOME" \

-Djava.awt.headless=true \

-Djava.io.tmpdir="$CATALINA_TMPDIR" \

org.apache.catalina.startup.Bootstrap "$@" start

你需要做的就是加入粗题那一行。


还是不行,再想办法.



package com.genius.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public final class ValidateImage implements Controller {
public ModelAndView handleRequest(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession();
//在内存中创建图象
int iWidth = 70, iHeight = 16;
BufferedImage image = new BufferedImage(iWidth, iHeight,
BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g = image.getGraphics();
//设定背景色
g.setColor(Color.white);
g.fillRect(0, 0, iWidth, iHeight);
//画边框
g.setColor(Color.black);
g.drawRect(0, 0, iWidth - 1, iHeight - 1);
//取随机产生的认证码(4位数字)
String rand = request.getParameter("rand");
rand = rand.substring(0, rand.indexOf("."));
switch (rand.length()) {
case 1:
rand = "000" + rand;
break;
case 2:
rand = "00" + rand;
break;
case 3:
rand = "0" + rand;
break;
default:
rand = rand.substring(0, 4);
break;
}
//将认证码存入SESSION
session.setAttribute("rand", rand);
//将认证码显示到图象中
g.setColor(Color.black);
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
g.drawString(rand, 10, 15);
//随机产生200个干扰点,使图象中的认证码不易被其它程序探测到
Random random = new Random();
for (int iIndex = 0; iIndex <200; iIndex++) {
int x = random.nextInt(iWidth);
int y = random.nextInt(iHeight);
g.drawLine(x, y, x, y);
}
//图象生效
g.dispose();
//输出图象到页面
ImageIO.write(image, "JPEG", response.getOutputStream());

return new ModelAndView();
}
}


解决方案2:我把它修改为


package com.genius.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public final class ValidateImage implements Controller {
public ModelAndView handleRequest(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession();
//在内存中创建图象
int iWidth = 70, iHeight = 16;
BufferedImage image = new BufferedImage(iWidth, iHeight,
BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g = image.getGraphics();
//设定背景色
g.setColor(Color.white);
g.fillRect(0, 0, iWidth, iHeight);
//画边框
g.setColor(Color.black);
g.drawRect(0, 0, iWidth - 1, iHeight - 1);
//取随机产生的认证码(4位数字)
String rand = request.getParameter("rand");
rand = rand.substring(0, rand.indexOf("."));
switch (rand.length()) {
case 1:
rand = "000" + rand;
break;
case 2:
rand = "00" + rand;
break;
case 3:
rand = "0" + rand;
break;
default:
rand = rand.substring(0, 4);
break;
}
//将认证码存入SESSION
session.setAttribute("rand", rand);
//将认证码显示到图象中
g.setColor(Color.black);
g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
g.drawString(rand, 10, 15);
//随机产生200个干扰点,使图象中的认证码不易被其它程序探测到
Random random = new Random();
for (int iIndex = 0; iIndex <200; iIndex++) {
int x = random.nextInt(iWidth);
int y = random.nextInt(iHeight);
g.drawLine(x, y, x, y);
}
//图象生效
g.dispose();
//输出图象到页面
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(response.getOutputStream());
encoder.encode(image);

return new ModelAndView();
}
}
修改后成功,,,