linechart.java

简单的‘基于web的图表生成系统’

package line;

import java.awt.*;
import java.awt.image.*;

import ajax.DataExchange;

public class LineChart{
	private String[] title = {"JAVA",".NET","C","PB","PASCAL"};
	private Color[]  color = {Color.red,Color.green,Color.yellow,Color.blue,Color.black};
	private int[] sales = new int[6];
	private int[] month = new int[6];
	
	//获取销售量
	public int[] getData(int month) {
		DataExchange de = new DataExchange();
		return de.getData(month);
	}
	
	public BufferedImage drawLineChart(){
		int width = 500, height = 375;

		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);	
		
		Graphics2D g2d =image.createGraphics();
		
		//打开反锯齿功能
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		
		g2d.setColor(Color.white);
		g2d.fillRect(0, 0, width, height);
		
		// 绘制新背景
		GradientPaint grayGP = new GradientPaint(0, 0, Color.red, width, height, new Color(200,200,200), true);
		g2d.setPaint(grayGP);
		g2d.fillRoundRect(5, 5, width-5, height-5, 50, 50);
		
		g2d.setPaint(Color.orange);
		g2d.fillRoundRect(2, 2, width-10, height-10, 50, 50);
		
		BasicStroke bs = new BasicStroke(5.0f);
		g2d.setStroke(bs);
		g2d.setPaint(Color.black);
		g2d.drawRoundRect(2, 2, width-10, height-10, 50, 50);
		
		GradientPaint blueGP = new GradientPaint(40, 40, Color.red, 120, 300, Color.WHITE, true);
		g2d.setPaint(blueGP);
		g2d.fillRect(75, 35, 390, 300);	//画图区域
		
		// 绘制图表标题
		String chartTitle = "2007年上半年计算机类图书销售统计图";
		g2d.setFont(new Font("方正粗宋简体", Font.PLAIN, 20));
		int length = g2d.getFontMetrics().stringWidth(chartTitle);
		g2d.setColor(Color.BLACK);
		g2d.drawString(chartTitle, (width-length)/2, 25);
		
		// 创建虚线笔划
		float[] dashes = {3.f};
		bs = new BasicStroke(1.0f, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND, 10, dashes, 0);
		g2d.setStroke(bs);
		g2d.setFont(new Font("宋体", Font.PLAIN, 12));
		String str="";
		int stringLength = 0;
		for (int i = 1; i <= 6; i++){
			// 绘制垂直方向虚线
			g2d.drawLine(5+i*70, 35, 5+i*70, 335);			
			// 绘制横轴上月份的说明文字
			str += i + "月";
			stringLength = g2d.getFontMetrics().stringWidth(str);
			g2d.drawString(str, 5+i*70-stringLength/2, 348);
			str = "";
		}		
		str ="";
		int stringHeight=0;		
		for (int i=0; i < 300; i += 30){
			// 绘制水平方向虚线
			g2d.drawLine(75, 40+i,455, 40+i);		
			// 绘制纵轴上销售量的说明文字
			str += 100-i/3;
			stringHeight = g2d.getFontMetrics().getAscent();
			stringLength = g2d.getFontMetrics().stringWidth(str);
			g2d.drawString(str, 65-stringLength, 40+i + stringHeight/2);
			str = "";
		}
		
		// 绘制坐标轴
		g2d.setStroke(new BasicStroke(3.0f));
		g2d.setColor(new Color(53, 76, 112));
		g2d.drawLine(75, 35, 75, 335);
		g2d.drawLine(75, 335, 465, 335);
		
		//实现折线的生成
		g2d.setFont(new Font("Courier New", Font.PLAIN, 12));
		for (int i=0; i < title.length; i++){
			// 初始化绘制数据
			int Sales = 0;
			int[] booksales = new int[5];
			for (int j = 0; j < month.length; j++){
				booksales = getData(j+1);
				Sales = booksales[i+1];
				sales[j] = 340-Sales*3;
				month[j] = 75+70*j;
			}			
			// 重新设置笔划
			g2d.setStroke(new BasicStroke(5.0f));
			g2d.setColor(color[i]);	
			// 绘制月销售量折线
			g2d.drawPolyline(month, sales, month.length);			
			// 绘制图例
			g2d.fillRect(70+i*50, 350, 10, 10);
			g2d.setColor(Color.BLACK);
			g2d.drawString(title[i], 80+i*50, 360);
		}
		return image;
	}
}