我需要通过 spring mvc 下载 xml 文件，并需要我的应用程序在使用 ModelAndView 成功下载后导航到另一个 jsp 页面。下载文件时出现错误
java.lang.IllegalStateException: getOutputStream() has already been called for this response
您能帮我解决这个问题吗？
@RequestMapping(value="/download",method = RequestMethod.GET)
public ModelAndView downloadXmlFile(HttpServletRequest request,
HttpServletResponse response) throws IOException {
servletcontext context = request.getsession().getservletcontext()
File downloadFile = new File("c:\\abc.xml");
FileInputStream inputStream = new FileInputStream(downloadFile);
// get MIME type of the file
String mimeType = context.getMimeType(fullPath);
if (mimeType == null) {
// set to binary type if MIME mapping not found
mimeType = "application/octet-stream";
}
System.out.println("MIME type: " + mimeType);
// set content attributes for the response
response.setContentType(mimeType);
response.setContentLength((int) downloadFile.length());
// set headers for the response
String headerKey = "Content-Disposition";
String headerValue = String.format("attachment; filename=\"%s\"",
downloadFile.getName());
response.setHeader(headerKey, headerValue);
// get output stream of the response
OutputStream outStream = response.getOutputStream();
byte[] buffer = new byte[4096];
int bytesRead = -1;
// write bytes read from the input stream into the output stream
while ((bytesRead = inputStream.read(buffer)) != -1) {
outStream.write(buffer, 0, bytesRead);
}
inputStream.close();
outStream.close();
return "Success";
}
最佳答案
- Create a Pojo Class Employee
import java.io.Serializable;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
public class Book implements Serializable {
String title;
int pages;
String isbn;
public String getTitle() {
return title;
}
@XmlElement
public void setTitle(String title) {
this.title = title;
}
public int getPages() {
return pages;
}
@XmlElement
public void setPages(int pages) {
this.pages = pages;
}
public String getIsbn() {
return isbn;
}
@XmlElement
public void setIsbn(String isbn) {
this.isbn = isbn;
}
}
- Create a Controller
import java.io.IOException;
import java.io.ObjectOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class SpringMVCController {
@RequestMapping(value = "/downloadXML")
public void downloadXML(HttpServletRequest request,
HttpServletResponse response) throws IOException, JAXBException {
Book book = new Book();
book.setTitle("Lord of the Rings");
book.setIsbn("Abbbbbb112");
book.setPages(400);
try {
response.setContentType("application/xml");
response.setHeader("Content-Disposition",
"attachment; filename=somefile.xml");
JAXBContext jaxbContext = JAXBContext.newInstance(Book.class);
Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
// output pretty printed
jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
// writing to a file
/*ObjectOutputStream out = new ObjectOutputStream(
response.getOutputStream());*/
jaxbMarshaller.marshal(book, response.getOutputStream());
// writing to console
// jaxbMarshaller.marshal(book, System.out);
response.flushBuffer();
} catch (Exception e) {
e.printStackTrace();
}
}
}
> 3. **Create a Jsp index.jsp**
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<%@ 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">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Spring MVC XML Download Example</title>
</head>
<body>
<form:form action="downloadXML" method="post" id="downloadXML">
<h3>Spring MVC XML Download Example</h3>
<input id="submitId" type="submit" value="Downlaod XML">
</form:form>
</body>
</html>
> # Header 1 # 4. Create web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
<display-name>Archetype Created Web Application</display-name>
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
</context-param>
<listener>
<listener- class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
> 5. Create dispatcher-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:component-scan base-package="com.javahonk.controller" />
<mvc:annotation-driven/>
</beans>
** 给出基础包名称**
当我们不使用response.flushBuffer()时，有时它不会写入内容
关于Spring MVC 中的 XML 文件下载，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18680336/