Spring 注解面面通之 @RequestPart

程序员文章站 2022-03-04 22:58:58

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@RequestPart用于将multipart/form-data类型数据映射到控制器处理方法的参数中。除了@RequestPart注解外，@RequestParam同样可以用于此类操作。

注解解析

① value:

绑定的参数名称，参数值为String类型。

② name:

绑定的参数名称，参数值为String类型。name和value可以同时使用，但两者的值需一致，否则会出现错误。

attribute 'name' and its alias 'value' are present with values of [XXX] and [XXX], but only one is permitted
1

③ required:

请求头中是否必须包含指定的值，默认值为true。

required为true时，如果请求头中缺少指定的值，则会抛出异常。

required为false时，如果请求头中缺少指定的值，则会返回null。

注解示例

方法参数可以使用@RequestPart或@RequestParam注释，参数类型可使用org.springframework.web.multipart.MultipartFile或javax.servlet.http.Part。

javax.servlet.http.Part是Servlet 3.0提供的类，需在Web中进行配置：

① 引入Servlet-api的3.0版本。

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.0.1</version>
    <scope>provided</scope>
</dependency>

② web.xml中，首先需配置web.xml版本，然后配置multipart-config标签。

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
	version="3.1" metadata-complete="true">
    
    ......
    
    <servlet>
        <servlet-name>springMVCServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                classpath*:/spring/applicationContext.mvc.xml
            </param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <!-- 多部分请求配置 -->
        <multipart-config>
            <maxFileSize>20480000</maxFileSize>
        </multipart-config>
    </servlet>
    
    ......
    
</web-app>

③ 配置Spring的多部分请求解析器，例如applicationContext.mvc.xml中增加配置。

<bean id="multipartResolver"
		class="org.springframework.web.multipart.support.StandardServletMultipartResolver">
</bean>

1) 建Controller，用来演示@RequestPart和@RequestParam使用方法。

package com.arhorchin.securitit.webannotations;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RequestPart;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;

/**
 * @author Securitit.
 * @note 演示@RequestPart使用方法.
 */
@Controller
@RequestMapping("/WebAnnotations")
public class RequestPartController {

    /**
     * logger.
     */
    private Logger logger = LoggerFactory.getLogger(RequestPartController.class);

    /**
     * 跳转页面.
     */
    @RequestMapping(
            value = "/RequestPart.html",
            method = RequestMethod.GET)
    public ModelAndView requestPartHtml(HttpServletRequest req, HttpServletResponse res, ModelMap modelMap)
            throws Exception {
        return new ModelAndView("webannotations/RequestPart", modelMap);
    }

    /**
     * RequestPart-MultipartFile接收参数.
     */
    @ResponseBody
    @RequestMapping(
            value = "/requestPartMultipartFile.do",
            method = RequestMethod.POST)
    public String requestPartMultipartFile(@RequestPart("file") MultipartFile multipartFile) throws Exception {
        logger.info("Current value of RequestPart [MultipartFile] : name is [" + multipartFile.getOriginalFilename()
                + "], file length is [" + multipartFile.getSize() + "]");
        return "Current value of RequestPart [MultipartFile] : name is [" + multipartFile.getOriginalFilename() + "], file length is ["
                + multipartFile.getSize() + "]";
    }

    /**
     * RequestPart-Part接收参数.
     */
    @ResponseBody
    @RequestMapping(
            value = "/requestPartPart.do",
            method = RequestMethod.POST)
    public String requestPartPart(@RequestPart("file") Part part) throws Exception {
        logger.info(
                "Current value of RequestPart [Part] : name is [" + part.getName() + "], file length is [" + part.getSize() + "]");
        return "Current value of RequestPart [Part] : name is [" + part.getName() + "], file length is [" + part.getSize() + "]";
    }
    
    /**
     * RequestParam-MultipartFile接收参数.
     */
    @ResponseBody
    @RequestMapping(
            value = "/requestParamMultipartFile.do",
            method = RequestMethod.POST)
    public String requestParamMultipartFile(@RequestParam("file") MultipartFile multipartFile) throws Exception {
        logger.info("Current value of RequestParam [MultipartFile] : name is [" + multipartFile.getOriginalFilename()
                + "], file length is [" + multipartFile.getSize() + "]");
        return "Current value of RequestParam [MultipartFile] : name is [" + multipartFile.getOriginalFilename() + "], file length is ["
                + multipartFile.getSize() + "]";
    }

    /**
     * RequestParam-Part接收参数.
     */
    @ResponseBody
    @RequestMapping(
            value = "/requestParamPart.do",
            method = RequestMethod.POST)
    public String requestParamPart(@RequestParam("file") Part part) throws Exception {
        logger.info(
                "Current value of RequestParam [Part] : name is [" + part.getName() + "], file length is [" + part.getSize() + "]");
        return "Current value of RequestParam [Part] : name is [" + part.getName() + "], file length is [" + part.getSize() + "]";
    }

    /**
     * Part接收参数.
     */
    @ResponseBody
    @RequestMapping(
            value = "/part.do",
            method = RequestMethod.POST)
    public String part(HttpServletRequest req) throws Exception {
        Part part = req.getPart("file");
        logger.info(
                "Current value of Part : name is [" + part.getName() + "], file length is [" + part.getSize() + "]");
        return "Current value of Part : name is [" + part.getName() + "], file length is [" + part.getSize() + "]";
    }

}

2) 建html，用来演示RequestPartController示例。

<!doctype html>
<html lang="en">
	<head>
		<meta charset="UTF-8">
		<meta name="Author" content="Securitit">
		<meta name="Keywords" content="-">
		<meta name="Description" content="Securitit @RequestPart 测试页面">
		<title>@RequestPart 测试页面</title>
	</head>
	<body>
		<div style="float: left; width: 520px; border: 1px solid #d8b1b1; padding: 20px 20px;">
			<h1 style="margin-top: -10px; text-align: center;">@RequestPart注解</h1>
			<div style="border: 1px solid #d8b1b1; padding: 10px 10px; padding-bottom: 30px; width: 500px;">
				<h1>RequestPart-MultipartFile 接收参数</h1>
				<form action="http://localhost:9199/spring-annotations/WebAnnotations/requestPartMultipartFile.do"
					method="post" enctype="multipart/form-data">
					<input type="file" name="file"/>
					<input type="submit" style="width: 100px; background-color: #e6dddd; margin-top: 30px; margin-left: 200px;"/>
				</form>
			</div>
			<div style="border: 1px solid #d8b1b1; padding: 10px 10px; padding-bottom: 30px; width: 500px; margin-top: 50px;">
				<h1>RequestPart-Part 接收参数</h1>
				<form action="http://localhost:9199/spring-annotations/WebAnnotations/requestPartPart.do"
					method="post" enctype="multipart/form-data">
					<input type="file" name="file"/>
					<input type="submit" style="width: 100px; background-color: #e6dddd; margin-top: 30px; margin-left: 200px;"/>
				</form>
			</div>
		</div>
		<div style="float: left; width: 520px; border: 1px solid #d8b1b1; padding: 20px 20px; margin-left: 50px;">
			<h1 style="margin-top: -10px; text-align: center;">@RequestParam注解</h1>
			<div style="border: 1px solid #d8b1b1; padding: 10px 10px; padding-bottom: 30px; width: 500px;">
				<h1>RequestParam-MultipartFile 接收参数</h1>
				<form action="http://localhost:9199/spring-annotations/WebAnnotations/requestParamMultipartFile.do"
					method="post" enctype="multipart/form-data">
					<input type="file" name="file"/>
					<input type="submit" style="width: 100px; background-color: #e6dddd; margin-top: 30px; margin-left: 200px;"/>
				</form>
			</div>
			<div style="border: 1px solid #d8b1b1; padding: 10px 10px; padding-bottom: 30px; width: 500px; margin-top: 50px;">
				<h1>RequestParam-Part 接收参数</h1>
				<form action="http://localhost:9199/spring-annotations/WebAnnotations/requestParamPart.do"
					method="post" enctype="multipart/form-data">
					<input type="file" name="file"/>
					<input type="submit" style="width: 100px; background-color: #e6dddd; margin-top: 30px; margin-left: 200px;"/>
				</form>
			</div>
		</div>
	</body>
</html>

3) 启动服务，访问http://localhost:9199/spring-annotations/WebAnnotations/RequestPart.html页面。

Spring 注解面面通之 @RequestPart

① @RequestPart注解-RequestPart-MultipartFile 接收参数

Spring 注解面面通之 @RequestPart

② @RequestPart注解-RequestPart-Part 接收参数

Spring 注解面面通之 @RequestPart

③ @RequestParam注解-RequestPart-MultipartFile 接收参数

Spring 注解面面通之 @RequestPart

④ @RequestParam注解-RequestPart-Part 接收参数

Spring 注解面面通之 @RequestPart

总结

@RequestPart和@RequestParam都可以处理multipart/form-data类型数据，本质上并没有区别，使用任何一个都能达到期望的效果。文件上传在实际应用中也是必不可少的。

若文中存在错误和不足，欢迎指正！

相关标签： Spring 全面解析 Spring RequestPart 注解示例解析

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