JAVA生成直方图Image
本程序修改至http://blog.csdn.net/lazy_p/article/details/5400268 ，以前是用的applet来呈现效果的。修改为返回一张BufferedImage图片，便于应用到项目中去，比如Web、C/S 
转自：http://blog.csdn.net/lazy_p/article/details/7206088
架构的程序都能应用。
package com.image.histogram; import java.awt.Color; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; /** * 柱状图 * * @author lazy_p * @date 2010-3-20 */ public class PlaneHistogram { private final int histogramWidth = 15;// 柱形图的宽度 private final int histogramPitch = 10;// 柱形图的间距 private float scaling = 1f;// 缩放的比例 private int maxStrWidth = 0; // 字符串需要的最大宽度 /** * <pre> * 参数b[i]和str[i]必须对应 * </pre> * * @param g * @param title * @param v * @param str * @param color * 可以为空 */ public BufferedImage paintPlaneHistogram(String title, int[] v, String[] str, Color[] color) { int width = str.length * histogramWidth+str.length*histogramPitch+50; int height = 255; scaling = calculateScale(v, height);//计算缩放比例 BufferedImage bufferImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = bufferImage.getGraphics(); g.setColor(Color.WHITE); g.fillRect(0, 0, width, height); FontMetrics metrics = null; g.setFont(new Font(null, Font.BOLD, 18)); g.setColor(Color.RED); g.drawString(title, (bufferImage.getWidth() - g.getFontMetrics() .stringWidth(title)) >> 1, 30);// 画标题 g.setFont(new Font(null, Font.PLAIN, 12)); metrics = g.getFontMetrics(); g.setColor(Color.BLACK); g.drawLine(10, 0, 10, height - 15); // 画Y坐标 g.drawLine(10, height - 15, width, height - 15);// 画X坐标 int j = 0; int colorCount=color.length; for (int i = 0; i < v.length; ++i) { if (color != null){ g.setColor(color[j]);// 设置前景色 if(j+1<colorCount){ j++; }else{ j=0; } }else{ g.setColor(Color.RED); } int x = 20 + i * (histogramPitch + histogramWidth + (maxStrWidth >> 1));// 计算出X坐标 int y = height - 16 - (int) (v[i] * scaling); // 计算出Y坐标 // 画占的比例 g.drawString(v[i] + "", x - ((metrics.stringWidth(v[i] + "") - histogramWidth) >> 1), y); // 画平面的柱状图 g.drawRect(x, y, histogramWidth, (int) (v[i] * scaling)); g.fillRect(x, y, histogramWidth, (int) (v[i] * scaling)); // 画每一项表示的东西 g.drawString(str[i], x - ((metrics.stringWidth(str[i]) - histogramWidth) >> 1), height - 2); } return bufferImage; } /** * 计算缩放比例 * @param v * @param h 图片的高度 * @return */ public float calculateScale(int[] v , int h){ float scale = 1f; int max = Integer.MIN_VALUE; for(int i=0 , len=v.length ; i < len ;++i){ if(v[i]>h && v[i]>max){ max=v[i]; } } if(max > h){ scale=((int)(h*1.0f/max*1000))*1.0f/1000; } return scale; } public static void main(String[] args) { PlaneHistogram planeHistogram = new PlaneHistogram(); BufferedImage image = planeHistogram.paintPlaneHistogram("颜色直方图", new int[]{100,200,300}, new String[]{"a" , "b" , "c"} , new Color[] {Color.RED, Color.GREEN, Color.BLACK, Color.BLUE }); File output = new File("G:/333.jpg"); try { ImageIO.write(image, "jpg", output); } catch (IOException e) { e.printStackTrace(); } } }转自：http://blog.csdn.net/lazy_p/article/details/7206088
jopen 
ajax