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      用JSP生成JPEG圖片
                
                  發表時間：2023-08-18             來源：明輝站整理相關軟件相關文章人氣：          
              
      [摘要]一、前言 　　 本文原作者為Tony Wang ，該文章涉及到文件的讀寫和jpg圖片的自動生成。利用jsp+servlet的技術，jsp調用servlet生成圖片。 二、首文件index.jsp如下...
      一、前言 

      　　 本文原作者為Tony Wang ，該文章涉及到文件的讀寫和jpg圖片的自動生成。利用jsp+servlet的技術，jsp調用servlet生成圖片。 

      二、首文件index.jsp如下： 

      <%-- 

      Author: Tony Wang 

      E-mail: lucky_tony@163.net 

      Date: 2001-01-01 

      如果對程序有什么疑問，可以和我聯系， 另外程序如果有什么bug，麻煩指出��！ 

      --%> 

      <%@ 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); 
      %> 


      <html> 
      <head> 
      <title></title> 
      <link href="css.css" rel="StyleSheet" type="text/css"></link> 
      </head> 

      <body> 
      <table width="180" border="1" bordercolor="#999999"> 
      <tr> 
      <td align=center>冰帆調查</td> 
      </tr> 
      <form name=frm method=post action=write.jsp> 
      <tr> 
      <td> 
      <% 
      String ss = null; 
      for (int i=0;i<4;i++) 
      { 
      ss = "<input type=\"radio\" name=\"choice\" value=" + i+">"+(char)(`A`+i)+"、"+ question[i]+"<br>"; 
      out.println(ss); 
      } 
      %> 
      </td> 
      </tr> 
      <tr> 
      <td align=center><input type=submit value="我 投 一 票"></td> 
      </tr> 
      <tr> 
      <td align=center><img src="/vote/servlet/VoteImage" width=150 height=100></td> 
      </tr> 
      </form> 
       
      </body> 
      </html> 


      三、寫文件write.jsp 

      <%-- 
      Author: Tony Wang 
      E-mail: lucky_tony@163.net 
      Date: 2001-01-01 
      如果對程序有什么疑問，可以和我聯系， 
      另外程序如果有什么bug，麻煩指出！！ 
      --%> 
      <%! 
      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原代碼：VoteImage.java : 

      /* 
      Author: Tony Wang 
      E-mail: lucky_tony@163.net 
      Date: 2001-01-01 
      如果對程序有什么疑問，可以和我聯系， 
      另外程序如果有什么bug，麻煩指出��！ 
      */ 
      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,HttpServletResponse response) 
      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,HttpServletResponse response) 
      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目錄下建立question.txt和count.txt文件分別用來保存投票的問題和投票的數量，用戶投票后，就修改count.txt的值。 

      為了對原作者表示感謝，這2個文件內容不變化，如下： 



      question.txt: 

      Yes,I think so! 

      No,I dont think so! 

      Sorry,I dont know the answer! 



      count.txt: 

      12 

      9 

      5 

      9 

      六、目錄結構： 

      (1)jsp文件和txt文件同一個目錄 

      (2).java文件是servlet目錄下 

      七、測試： 

      http://[server:port]/dir/index.jsp


              
              
                 
              
                                            
                              		       
                          
                           		  
        
                            
      
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