在做jsp图片上传到数据库和显示时,遇到
java.lang.IllegalStateException: getOutputStream() has already been called for this response
异常,查了下,原因在于我是在jsp里写的OutputStream的,应该放到Servlet中,jsp的本质不就是Servlet吗?..为什么放在不同为位置就会不一样了..郁闷~
还有这个异常,关于涉及到IO操作时会经常遇到,遇到和我相似的,不妨试试!
出错时的代码:写在jsp中的,功能是从数据库中读取图片 showimage.jsp
<%@ page contentType="text/html; charset=utf-8"%>
<%@ page import="java.io.*,java.sql.*,bean.*"%>
<%
int id=Integer.parseInt(request.getParameter("id"));
String sql = " SELECT photo FROM test WHERE id="+id;
PreparedStatement pstmt = null;
ConnectMysql connectMysql = new ConnectMysql();
try {
pstmt = connectMysql.openConnection().prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
ServletOutputStream outs = response.getOutputStream();
response.setContentType("image/jpeg");
if (rs.next()) {
Blob b = rs.getBlob("photo");
long size = b.length();
byte[] bs = b.getBytes(1, (int) size);
outs.write(bs);
outs.flush();
outs.close();
rs.close();
} else {
rs.close();
}
} finally {
pstmt.close();
connectMysql.closeConnection();
}
%>
改写到servlet中后,没出错:ImageServlet
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
//PrintWriter out = response.getWriter();
int id=Integer.parseInt(request.getParameter("id"));
String sql = " SELECT photo FROM test WHERE id="+id;
PreparedStatement pstmt = null;
ConnectMysql connectMysql = new ConnectMysql();
try {
pstmt = connectMysql.openConnection().prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
ServletOutputStream outs = response.getOutputStream();
response.setContentType("image/jpeg");
if (rs.next()) {
Blob b = rs.getBlob("photo");
long size = b.length();
byte[] bs = b.getBytes(1, (int) size);
outs.write(bs);
outs.flush();
outs.close();
rs.close();
} else {
rs.close();
}
} catch(Exception e){
e.printStackTrace();
}finally {
connectMysql.closeConnection();
}
//out.flush();
//out.close();
}注意用了OutputStream就不能使用PrintWriter了,因为都是输出流
顺便把mysql的存取图片介绍完整!
servlet部分:
接收处理客户端上传过来的photo:
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
boolean flag = false;
String path="";
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
try{
String photo=request.getParameter("photo").replace('\\', '/');
Test test = new Test();
test.setPhoto(photo);
flag = DaoFactory.getTestDaoInstance().insert(test);
if(flag){
path = "success.jsp";
}else{
path = "fail.jsp";
}
request.getRequestDispatcher(path).forward(request, response);
}catch(Exception e){
e.printStackTrace();
}
out.flush();
out.close();
}vo部分:
package vo;
public class Test {
String photo;
public String getPhoto() {
return photo;
}
public void setPhoto(String photo) {
this.photo = photo;
}
}
dao部分:
向数据库中插入图片:
public boolean insert(Test test) throws Exception {
Boolean flag=false;
String sql = "INSERT INTO test(name,password,email,photo) VALUES(?,?,?,?)";
PreparedStatement pstmt = null;
ConnectMysql connectMysql = new ConnectMysql();
FileInputStream fis;
File file;
try {
file = new File(test.getPhoto());
fis = new FileInputStream(file);
pstmt = connectMysql.openConnection().prepareStatement(sql);
pstmt.setString(1, "test");
pstmt.setString(2, "test");
pstmt.setString(3, "test");
pstmt.setBinaryStream(4, fis, (int) file.length());
pstmt.executeUpdate();
pstmt.close();
flag=true;
} catch (Exception e) {
e.printStackTrace();
} finally {
connectMysql.closeConnection();
}
return flag;
}
调用的代码:
<td width="152" rowspan="3"><img src="showimage.jsp?id=0" width="140" height="140"></td>
把上面的showimage.jsp 改为ImageServlet就可以了,注意web.xml中servlet配置的路径.
ref:
http://www.coderanch.com/t/289883/JSP/java/IllegalStateException-getOutputStream-has-already-been
posted on 2009-05-27 15:48
fl1429 阅读(1367)
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