【下载文档:  JSP生成jpeg图片用于投票.txt 】

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JSP生成jpeg图片用于投票
一、前言 本文原作者为Tony Wang ，该文章涉及到文件的读写和jpg图片的自动生成。利用jsp+servlet的技术，jsp调用servlet生成图片。 二、首文件index.jsp如下：<%-- Author: Tony Wang E-mail: lucky_tony@163.net Date: 2001-01-01 如果对程序有什么疑问，可以和我联系， 另外程序如果有什么bug，麻烦指出！！ --%><%@ page contentType="text/html;charSet=gb2312"%><%response.setHeader("Cache-Control","no-store");response.setDateHeader("Expires",0);%><%!public String[] getQuestion(String s){String[] strQ = new String[4];String strTemp = null;int i;java.io.RandomAccessFile rf = null;try {rf = new java.io.RandomAccessFile(s,"r");} catch(Exception e){System.out.println(e);System.exit(0);}for(i=0;i<4;i++) {try {strTemp = rf.readLine();} catch(Exception e) {strTemp = "None Question";}if(strTemp==null)strTemp = "None Question";strQ[i] = strTemp;}return strQ;}%><%String s = null;String[] question = new String[4];s = request.getRealPath("question.txt");question = getQuestion(s);%>

冰帆调查

<%String ss = null;for (int i=0;i<4;i++){ss = ""+(char)("A"+i)+"、"+ question[i]+" ";out.println(ss);}%>

三、写文件write.jsp<%--Author: Tony WangE-mail: lucky_tony@163.netDate: 2001-01-01如果对程序有什么疑问，可以和我联系，另外程序如果有什么bug，麻烦指出！！--%><%!public int[] getNumber(String s){int[] mCount = new int[4];String strTemp = null;int i;java.io.RandomAccessFile rf = null;try {rf = new java.io.RandomAccessFile(s,"r");} catch(Exception e){System.out.println(e);System.exit(0);}for(i=0;i<4;i++) {try {strTemp = rf.readLine();} catch(Exception e) {strTemp = "0";}if(strTemp==null)strTemp = "0";mCount[i] = new Integer(strTemp).intValue();}return mCount;}public void setNumber(String s,int[] x){try {java.io.PrintWriter pw = new java.io.PrintWriter(new java.io.FileOutputStream(s));for (int i=0;i<4;i++){pw.println(x[i]+"");}pw.close();} catch(Exception e) {System.out.println("Write file error:"+e.getMessage());}}%><%String tmp = null;int choice = -1;int[] count = new int[4];tmp = request.getParameter("choice");if (tmp==null){} else {choice = new Integer(tmp).intValue();}/////////////String s = request.getRealPath("count.txt");if(choice>=0){count = getNumber(s);count[choice]++;setNumber(s,count);}response.sendRedirect("index.jsp");%>四、servlet原代码：VoteImage.java :/*Author: Tony WangE-mail: lucky_tony@163.netDate: 2001-01-01如果对程序有什么疑问，可以和我联系，另外程序如果有什么bug，麻烦指出！！*/import java.io.*;import java.util.*;import com.sun.image.codec.jpeg.*;import javax.servlet.*;import javax.servlet.http.*;import java.awt.*;import java.awt.geom.*;import java.awt.image.*;public class VoteImage extends HttpServlet {private String strFile = null;private Color color[]={Color.red,Color.black,Color.orange,Color.green};private int baseAng = 30;public void doGet(HttpServletRequest request,HttpServletResponseresponse)throws ServletException,IOException {strFile = request.getRealPath("count.txt");float[][] xy = new float[4][2];xy = getNumAndPercent(strFile);int[] ang = new int[4];ang[0] = (int)(xy[0][1]*360);ang[1] = (int)(xy[1][1]*360);ang[2] = (int)(xy[2][1]*360);ang[3] = 360-ang[0]-ang[1]-ang[2];response.setHeader("Cache-Control","no-store");response.setDateHeader("Expires",0);response.setContentType("image/jpeg");ServletOutputStream out=response.getOutputStream();BufferedImage image=new BufferedImage(150,100,BufferedImage.TYPE_INT_RGB);Graphics2D g=(Graphics2D)image.getGraphics();g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);g.setColor(Color.white);g.fillRect(0,0,150,100); AffineTransform at = null;Arc2D arc = null;int fromAng = baseAng;at = AffineTransform.getRotateInstance((-20*java.lang.Math.PI)/180,45,37);g.setTransform(at);int r =6;int dx = (int)(r*java.lang.Math.cos((baseAng+ang[0])/2.0*java.lang.Math.PI/180));int dy = (int)(r*java.lang.Math.sin((baseAng+ang[0])/2.0*java.lang.Math.PI/180));arc = new Arc2D.Double(10+dx,24-dy,80,50,fromAng,ang[0],Arc2D.PIE);g.setColor(color[0]);g.fill(arc);fromAng+=ang[0];for (int i=1;i<4;i++){g.setColor(color[i]);arc = new Arc2D.Double(10,24,80,50,fromAng,ang[i],Arc2D.PIE);g.fill(arc);fromAng+=ang[i];if (fromAng>360){fromAng-=360;}}at = AffineTransform.getRotateInstance(0,arc.getCenterX(),arc.getCenterY());g.setTransform(at);for (int i=0;i<4;i++){g.setColor(color[i]);g.fillRect(100,15*i+20,10,10);g.drawString((char)("A"+i)+"",120,15*i+20+8);}JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);encoder.encode(image);out.close();}public void doPost(HttpServletRequest request,HttpServletResponseresponse)throws ServletException,IOException {doGet(request,response);}public synchronized float[][] getNumAndPercent(String sFileName){float xx[][] = new float[4][2];int totalNum = 0 ;String strTemp = null;int i = 0;java.io.RandomAccessFile rf = null;try {rf = new java.io.RandomAccessFile (sFileName,"r");} catch(Exception e){System.out.println(e);System.exit(0);}for (i=0;i<4;i++){int m=0;try {strTemp = rf.readLine();} catch (Exception e){strTemp = "0";}if (strTemp == null) strTemp = "0";m = new Integer(strTemp).intValue();xx[i][0]=m;totalNum += m;}if (totalNum==0) totalNum=1;for ( i=0;i<4;i++){xx[i][1] = xx[i][0]/totalNum;}return xx;}}五、在index.jsp目录下建立question.txt和count.txt文件分别用来保存投票的问题和投票的数量，用户投票后，就修改count.txt的值。为了对原作者表示感谢，这2个文件内容不变化，如下：question.txt:Yes,I think so! No,I dont think so! Sorry,I dont know the answer! count.txt:12959 六、目录结构：(1)jsp文件和txt文件同一个目录(2).java文件是servlet目录下七、测试：http://[server:port]/dir/index.jsp