display.java

来自「weblogic应用全实例」· Java 代码 · 共 47 行

//定义本类所在的包
package examples.jsp.tagext.counter;
//定义本类引入的类
import java.io.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import javax.servlet.http.*;

/**
 * 这个类在jsp页中显示一个图形页击中次数。
 */

public class Display extends TagSupport {
  
  
  private static String IMAGE_DIR="images/numbers/";
  //实现doStartTag方法
  public int doStartTag() throws JspException {
      //jsp临时目录
    File tempDir = (java.io.File) pageContext.getServletContext().
       getAttribute("javax.servlet.context.tempdir");
    File countFile = new File(tempDir, "count.tmp");
    //读取计数
    String countStr = String.valueOf(Count.getCount(countFile));
    
    try {
    //返回给客户端	
      JspWriter out = pageContext.getOut();
      int i = 0;
      while(i < countStr.length())
      {
        out.print("<img src=\""+IMAGE_DIR+countStr.charAt(i)+
                  ".gif\" height=40 >");
        i++;
      }
    } catch(IOException ioe) {
      System.out.println("Failed to insert counter display");
      ioe.printStackTrace();
      throw new JspException("Failed to insert counter display");
    }
    
    return(SKIP_BODY);
  }
}