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. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doDelete method of the servlet. <br>
*
* 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. <br>
*
* 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. <br>
*
* 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. <br>
*
* 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. <br>
*
* @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");
}
}
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