我想将数据库中的所有图像显示/检索到jsp页面[重复]答案

【问题标题】：i want to display/retrive all the images from the database to a jsp page [duplicate]我想将数据库中的所有图像显示/检索到jsp页面[重复]
【发布时间】：2015-11-14 05:40:46
【问题描述】：

我是第一次做这个任务，所以我用谷歌搜索了这段代码并尝试了解其中的内容。实现此代码后我喜欢的是它无法满足我的要求，它只显示一张图像，用于从数据库中检索所有图像并抛出异常 -

java.lang.IllegalStateException: getOutputStream() 已为此响应调用。

在我用谷歌搜索这个异常之后，我在这个特定网站上读到的关于这个的内容是在这个链接中 -

java.lang.IllegalStateException: getOutputStream() has already been called for this response

我再次尝试这样做，但没有得到结果。不管我在谷歌这个异常之前做了什么，之后我会告诉你

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<a href="index.jsp">click to display images</a>
</body>
</html>

这是我的 index.jsp 页面

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"     "http://www.w3.org/TR/html4/loose.dtd">

<%@ page import="java.io.*"%>

<%@ page import="java.sql.*,java.util.*"%>
<%!ServletOutputStream o; %>
<%!ArrayList<Blob> bl; %>


<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>men's trousers</title>
</head>
<body>


<%
try {

Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306      /imgdb","root","annie1993");
PreparedStatement stmt = con.prepareStatement("select IMAGE from myimages ");
ResultSet rs = stmt.executeQuery();
//ResultSet rs1=stmt.executeQuery("select count(id) from student_profile");
bl=new ArrayList<Blob>();
while(rs.next()) {
System.out.println("st-1");
bl.add(rs.getBlob(1));
System.out.println("st-2");
}
//if(rs1.next())
//System.out.println(bl.size()+"size="+rs1.getInt(1));
for(int i=0;i<bl.size();i++){
System.out.println("st-3");
Blob b=bl.get(i);
System.out.println("st-4 "+b);
byte brr[]=new byte[(int)b.length()];
System.out.println("st-6");
brr=b.getBytes(1,(int)b.length());
System.out.println("st-7 "+brr);
// display the image
response.setContentType("image/jpg");
o = response.getOutputStream();
System.out.println("st-8 "+o);
%><table><tr><td align='left'>
<img src=<%o.write(brr); %> width="117" height="160"
>
</td></tr></table>
<%
out.println("<br>");
System.out.println("st-9 ");
}
} catch (Exception e) {
out.println("Unable To Display image");
out.println("Image Display Error=" + e.getMessage());
return;
} 
%>
</div></td></tr></table></td></tr>
</table>


</body>
</html>

我得到的结果是

INFO: Server startup in 6916 ms
st-1
st-2
st-1
st-2
st-1
st-2
st-1
st-2
st-1
st-2
st-3
st-4 com.mysql.jdbc.Blob@1a368ee
st-6
st-7 [B@886ce4
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@1259b5d
st-6
st-7 [B@1c9704f
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@7fc51e
st-6
st-7 [B@1d06ac2
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@bcf156
st-6
st-7 [B@bb7c6
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@4ccfac
st-6
st-7 [B@f42b5d
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
Aug 20, 2015 6:28:43 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path   [/display_multiple_images] threw exception [java.lang.IllegalStateException: getOutputStream() has already been called for this response] with root cause
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:578)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:212)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:115)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:108)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:183)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:120)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:184)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at   org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:43    1)
at  org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at  java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

Aug 20, 2015 6:28:44 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path  [/display_multiple_images] threw exception [java.lang.IllegalStateException: getOutputStream() has already been called for this response] with root cause
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:578)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:212)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:115)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:108)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:183)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:120)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:184)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:431)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1086)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:659)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1558)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
at   java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

st-1
st-2
st-1
st-2
st-1
st-2
st-1
st-2
st-1
st-2
st-3
st-4 com.mysql.jdbc.Blob@1280329
st-6
st-7 [B@1dc1aa
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@5de911
st-6
st-7 [B@47eb95
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@197937f
st-6
st-7 [B@1190cf6
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@1375e5
st-6
st-7 [B@12323b1
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9 
st-3
st-4 com.mysql.jdbc.Blob@664f41
st-6
st-7 [B@1bb8fc7
st-8 org.apache.catalina.connector.CoyoteOutputStream@cea65d
st-9

在我用谷歌搜索这个异常之后，我无法获得单个图像，但这次它没有抛出任何异常这是代码

<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<a href="Displayimage">click to display images</a>
</body>
</html>

这是我的 Displayimage servlet

package com.mulimgdis;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;

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

/**
* Servlet implementation class Displayimage
*/
public class Displayimage extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
 * @see HttpServlet#HttpServlet()
 */
 public Displayimage() {
    super();
    // TODO Auto-generated constructor stub
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request,  HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub


    PrintWriter out = response.getWriter();

    ServletOutputStream o; 
    ArrayList<Blob> bl;
    try {




         Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection con  =DriverManager.getConnection("jdbc:mysql://localhost:3306/imgdb","root","annie1993");
    PreparedStatement stmt = con.prepareStatement("select IMAGE from myimages ");
    ResultSet rs = stmt.executeQuery();
    //ResultSet rs1=stmt.executeQuery("select count(id) from student_profile");
     bl=new ArrayList<Blob>();
    while(rs.next()) {
    System.out.println("st-1");
    bl.add(rs.getBlob(1));
    System.out.println("st-2");
    }
    //if(rs1.next())
    //System.out.println(bl.size()+"size="+rs1.getInt(1));
    for(int i=0;i<bl.size();i++){
    System.out.println("st-3");
    Blob b=bl.get(i);
    System.out.println("st-4 "+b);
    byte brr[]=new byte[(int)b.length()];
    System.out.println("st-6");
    brr=b.getBytes(1,(int)b.length());
    System.out.println("st-7 "+brr);
    // display the image
    response.reset();
    response.setContentType("image/jpg");
     o = response.getOutputStream();
     System.out.println("st-8 "+o);

     /* 
      * 
      *   %><table><tr><td align='left'>
 <img src=<%o.write(brr); %> width="117" height="160"
 >
 </td></tr></table>
 <%
 out.println("<br>");
 System.out.println("st-9 ");
 }
 } catch (Exception e) {
out.println("Unable To Display image");
out.println("Image Display Error=" + e.getMessage());
return;
} 
%>
</div></td></tr></table></td></tr>
</table>
*/

     o.write(brr);
     response.getOutputStream().flush();  

     out.println("<br>");
     System.out.println("st-9 ");
     }
    } catch (Exception e) {
    out.println("Unable To Display image");
    out.println("Image Display Error=" + e.getMessage());
    return;
    }  


}

【问题讨论】：

如果将response.getOutputStream().flush(); 替换为o.flush 会怎样？
替换后我只得到一个图像，因为我从 index.jsp 得到了但是这次我没有得到那个异常

标签： java jsp servlets

【解决方案1】：

查看此文档：httpServletResponse.getOutputStream()

你看到了

可以调用此方法或 getWriter() 来编写正文，而不是同时调用两者。

应该是问题

【讨论】：

好的，我明白了，但是在从我的 Displayimage servlet 类中删除所有 getWriter() 之后，我没有得到那个异常，但最终我只得到了单个图像，而不是数据库中的所有图像。在省略这个 getWriter() 之后，请查看我的 servlet 类并告诉我应该在其中写入什么来获取所有图像以及如何
尝试更改您的 sql 查询：从 myimages ORDER BY image_name 中选择 IMAGE。所以看看显示的是哪张图片，如果这是查询中的最后一张或第一张，那可能是浏览器当时可以接收并显示单个图像。