在JSP中如何从数据流中取得图片数据并按随意位置显示- JSP

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在JSP中如何从数据流中取得图片数据并按随意位置显示

出处:互联网 整理: 软晨网（RuanChen.com） 发布: 2009-09-03 浏览: 120 ::

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java 设计模式之Observer 三级级联下拉菜单实现

在JSP中如何从数据流中取得图片数据并按随意位置显示
 在Servlet只能显示一个图片,并且用图层定位时写代码很是麻烦,并且如果是从流中读数据,就只能显示一个图片,同时,还不能解决图片和文字信息的同时输出和位置叠加
 在JSP中,我们可以用以下办法来解决
 首先,写一个Servlet负责从数据文件或数据库等数据来源中得到数据流并输出
 然后在JSP文件中多次调用此Servlet来请求并取的图片数据流并显示
我的Servlet代码入下
InitializeMap.java
/*
* 创建日期 2005-5-30
*
* TODO 要更改此生成的文件的模板，请转至
* 窗口－首选项－ Java －代码样式－代码模板
*/
package zy.ser;

import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
* @author Administrator
*
* TODO 要更改此生成的类型注释的模板，请转至窗口－首选项－ Java －代码样式－代码模板
*/
public class InitializeMap extends HttpServlet {
 String imgName;
 public InitializeMap() {
 super();
 }

 /**
 * Destruction of the servlet. 
 */
 public void destroy() {
 super.destroy(); // Just puts "destroy" string in log
 // Put your code here
 }

 /**
 * The doDelete method of the servlet. 
 *
 * This method is called when a HTTP delete request is received.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doDelete(HttpServletRequest request,
 HttpServletResponse response) throws ServletException, IOException {

 // Put your code here
 }

 /**
 * The doGet method of the servlet. 
 *
 * This method is called when a form has its tag value method equals to get.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 this.initURI(request);
 File file=new File(this.getServletContext().getRealPath("img\\map1\\"+this.imgName+".jpg"));
 System.out.println(file);
 FileInputStream fis=new FileInputStream(file);
 System.out.println(fis);
 int length=fis.available();
 System.out.println(length);
 byte[] data=new byte[length];
 //read the stream data into the stream
 fis.read(data);
 fis.close();
 OutputStream sos=response.getOutputStream();
 //read the stream data into the output stream
 response.setContentType("image/*");
 sos.write(data);
 sos.flush();
 sos.close();
 }

 /**
 * The doPost method of the servlet. 
 *
 * This method is called when a form has its tag value method equals to
 * post.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doPost(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {

 response.setContentType("text/html");
 PrintWriter out = response.getWriter();
 out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
 out.println("<HTML>");
 out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
 out.println(" <BODY>");
 out.print(" This is ");
 out.print(this.getClass());
 out.println(", using the POST method");

 out.println(" </BODY>");
 out.println("</HTML>");
 out.flush();
 out.close();

 }

 /**
 * The doPut method of the servlet. 
 *
 * This method is called when a HTTP put request is received.
 *
 * @param request
 * the request send by the client to the server
 * @param response
 * the response send by the server to the client
 * @throws ServletException
 * if an error occurred
 * @throws IOException
 * if an error occurred
 */
 public void doPut(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {

 // Put your code here
 }

 /**
 * Returns information about the servlet, such as author, version, and
 * copyright.
 *
 * @return String information about this servlet
 */
 public String getServletInfo() {
 return "This is my default servlet created by Eclipse";
 }

 /**
 * Initialization of the servlet. 
 *
 * @throws ServletException
 * if an error occure
 */
 public void init() throws ServletException {
 // Put your code here
 }
 public void initURI(HttpServletRequest request){
 this.imgName=request.getParameter("imgName");
 }
}

java 设计模式之Observer 三级级联下拉菜单实现

在JSP中如何从数据流中取得图片数据并按随意位置显示

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