一个画柱状图形的例子，在页面中显示

<%@ page language="java" contentType="charset=gb2312"%>

response.setHeader("Cache-Control","no-store"); //HTTP 1.1

response.setHeader("Pragma","no-cache"); //HTTP 1.0

response.setDateHeader ("Expires", 0); //prevents caching at the proxy server

<%@ page import="java.io.OutputStream" %>

<%@ page import="java.awt.image.*" %>

<%@ page import="java.awt.*,java.awt.font.*,java.awt.geom.*,javax.imageio.*,java.io.*" %>

<%@ page import="com.sun.image.codec.jpeg.*" %>

<%@ page import="acec.*,java.util.*" %>

<html>

<head>

//数据数组

String datanames[] = {"第一季度", "第二季度", "第三季度"};

int datavalues[] = {111, 620, 33};

int WIDTH = 600;

int HEIGHT =400;

int innerHEIGHT = HEIGHT-100;

int innerWIDTH = WIDTH-20;

int maximum = 0;

for(int i=0; i<datavalues.length; i++)

{

if(datavalues[i] > maximum)

{

maximum = datavalues[i];

}

response.setContentType("image/jpeg");

BufferedImage bi = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

Graphics2D biContext = bi.createGraphics();

//插入背景图案

try{

Image image=ImageIO.read(new File("bg.jpg"));

biContext.drawImage(image,0,0,WIDTH,HEIGHT,null);

}catch(Exception ex){System.out.println(ex.toString());}

//开始绘图

int barWidth = innerWIDTH/(datavalues.length*4);

//System.out.println("barWidth="+barWidth);

for(int i=0,ii=0; i<datavalues.length; i++,ii++)

{

Color barColor=null;

Color barColor1=null;

if(ii==0)//蓝色

{

barColor=new Color(48,36,189);

barColor1 = new Color(201,201,245);

}

else if(ii==1)//绿色

{

barColor=new Color(62,145,68);

barColor1 = new Color(210,236,236);

}

else if(ii==2)//红色

{

barColor=Color.red;

barColor1 = new Color(253,181,199);

ii=-1;

}

int currentValue = datavalues[i];

//Set bar width

int barHeight = (innerHEIGHT * currentValue) / maximum;

biContext.setColor(barColor);

Rectangle barRect = new Rectangle(barWidth,barHeight);

//取字的宽度

Font f=biContext.getFont();

FontRenderContext context=biContext.getFontRenderContext();

Rectangle2D bounds_top=f.getStringBounds("人气值："+currentValue,context);

Rectangle2D bounds=f.getStringBounds(datanames[i],context);

biContext.setColor(Color.black);

//柱形的定位

int locationY=HEIGHT-barHeight-20;

int locationX=innerWIDTH/datavalues.length*(i+1)-barWidth/2;

if(datavalues.length%2!=0)

locationX=innerWIDTH/(datavalues.length+1)*(i+1)-barWidth/2;

barRect.setLocation(locationX,locationY);

biContext.drawString(datanames[i],(int)((locationX+barWidth/2)-bounds.getWidth()/2),HEIGHT-5);

biContext.drawString("人气值："+currentValue, (int)((locationX+barWidth/2)-bounds_top.getWidth()/2),locationY-10);

biContext.setPaint(new GradientPaint(locationX,locationY,barColor1,locationX+barWidth,locationY,barColor));

biContext.fill(barRect);

}

/////////////////////////////////////////////////////////////////////////////////////

//保存图片

/////////////////////////////////////////////////////////////////////////////////////

OutputStream bos = new FileOutputStream(application.getRealPath("tp.jpeg"));

JPEGImageEncoder encoder1 = JPEGCodec.createJPEGEncoder(bos);

encoder1.encode(bi);

bos.close();

</html>