Java：一个画柱状图形的例子，在页面中显示

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一个画柱状图形的例子，在页面中显示

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<%@ 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>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"></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();

%>
<body leftmargin="0" topmargin="0">
<img src="tp.jpeg" width="600" height="400">
</html>

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