Spring MVC高级配置

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1、文件上传配置

1.1 点睛

文件上传是一个项目经常用到的功能，Spring MVC通过配置一个MultipartResolver来上传文件。

在Spring的控制器中，通过MultipartFile file来接受文件，通过MultipartFile[] files接受多个文件上传。

1.2 示例

1、添加文件上传依赖

<dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>${servlet.version}</version><!-- 编译和测试的时候用 --><scope>provided</scope></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>jsp-api</artifactId><version>${jsp.version}</version><scope>provided</scope></dependency>

2、上传页面

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!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=UTF-8"><title>upload page</title></head><body><div class="upload"><form action="upload" enctype="multipart/form-data" method="post"><input type="file" name="file"/><br/><input type="submit" value="上传"></form></div></body></html>

3、添加跳转到upload页面的ViewController

@Overridepublic void addViewControllers(ViewControllerRegistry registry) {// 重定向registry.addRedirectViewController("index3", "index");// 直接配置请求路径（index3）和页面（index.jsp）之间的映射。// 无任何业务逻辑只是简单的业务逻辑可以这样子写，代码更简洁，管理集中registry.addViewController("index2").setViewName("index");registry.addViewController("forUpload").setViewName("upload");}

4、MultipartResolver的配置

@Beanpublic MultipartResolver multipartResolver() {CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();multipartResolver.setMaxUploadSize(10000000);return multipartResolver;}

5、控制器

package com.chenfeng.xiaolyuh.controller;import java.io.File;import java.io.IOException;import org.apache.commons.io.FileUtils;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RestController;import org.springframework.web.multipart.MultipartFile;@RestController // 声明是一个控制器，并且返回时不需要@ResponseBodypublic class FileUploadController {@RequestMapping(value = "upload", method = RequestMethod.POST) public Object getjson (MultipartFile file) throws IOException{FileUtils.writeByteArrayToFile(new File("E:/upload/" + file.getOriginalFilename()), file.getBytes());return "OK";}}

2、自定义HttpMessageConverter（消息转换器）

2.1 点睛

HttpMessageConverter是用来处理request和response里的数据。Spring为我内置了大量的HttpMessageConverter，列如MappingJackson2HttpMessageConverter和StringHttpMessageConverter等。这里我们将演示自定义一个HttpMessageConverter，并注册到Spring MVC。

2.2 示例

2.2.1 自定义HttpMessageConverter

package com.chenfeng.xiaolyuh.message.converter;import java.io.IOException;import java.nio.charset.Charset;import org.springframework.http.HttpInputMessage;import org.springframework.http.HttpOutputMessage;import org.springframework.http.MediaType;import org.springframework.http.converter.AbstractHttpMessageConverter;import org.springframework.http.converter.HttpMessageNotReadableException;import org.springframework.http.converter.HttpMessageNotWritableException;import org.springframework.util.StreamUtils;import com.chenfeng.xiaolyuh.entity.DemoObj;/** * 继承AbstractHttpMessageConverter类来实现自定义的HttpMessageConverter（消息转换器） */public class MyHttpMessageConverter extends AbstractHttpMessageConverter<DemoObj> {/** *  * @Description 建立我们自定义的媒体类型"application/x-wisely" */public MyHttpMessageConverter() {super(new MediaType("application", "x-wisely", Charset.forName("UTF-8")));}/** * 表明HttpMessageConverter（消息转换器）只处理DemoObj类 */@Overrideprotected boolean supports(Class<?> clazz) {// 判断clazz类是不是DemoObj类或者是DemoObj的子类return DemoObj.class.isAssignableFrom(clazz);}/** * 重写readInternal方法，处理请求数据。代码表明我们处理有“-”隔开的数据，并转成DemoObj对象 */@Overrideprotected DemoObj readInternal(Class<? extends DemoObj> clazz, HttpInputMessage inputMessage)throws IOException, HttpMessageNotReadableException {String temp = StreamUtils.copyToString(inputMessage.getBody(), Charset.forName("UTF-8"));String[] tempArr = temp.split("-");return new DemoObj(Long.parseLong(tempArr[0]), tempArr[1]);}/** * 重写writeInternal方法，处理数据如何输出到response。此处，我么在原样输出前面加上“HELLO” */@Overrideprotected void writeInternal(DemoObj t, HttpOutputMessage outputMessage)throws IOException, HttpMessageNotWritableException {String out = "HELLO:" + t.getId() + "-" + t.getName();outputMessage.getBody().write(out.getBytes());}}

2.2.2 配置

在addViewControllers方法中添加访问页面映射

registry.addViewController("converter").setViewName("converter");

配置自定义HttpMessageConverter，在Spring MVC里注册HttpMessageConverter有两种方法：

configureMessageConverters：覆盖掉Spring MVC默认注册的多个HttpMessageConverter

extendMessageConverters：仅添加一个自定义的HttpMessageConverter，不覆盖默认的HttpMessageConverter

        @Beanpublic MyHttpMessageConverter converter() {return new MyHttpMessageConverter();}/** * 覆盖掉Spring MVC默认注册的多个HttpMessageConverter */@Overridepublic void configureMessageConverters(List<HttpMessageConverter<?>> converters) {super.configureMessageConverters(converters);}/** * 仅添加一个自定义的HttpMessageConverter，不覆盖默认的HttpMessageConverter */@Overridepublic void extendMessageConverters(List<HttpMessageConverter<?>> converters) {// 添加一个自定义的消息转换converters.add(converter());}

2.2.3 控制器

package com.chenfeng.xiaolyuh.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import com.chenfeng.xiaolyuh.entity.DemoObj;@Controller // 声明是一个控制器，并且返回时不需要@ResponseBodypublic class ConverterController {@RequestMapping(value = "/convert", produces = { "application/x-wisely" })// 自定义的媒体类型@ResponseBody    public DemoObj convert(@RequestBody DemoObj demoObj) {        return demoObj;    }}

2.2.4 页面

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!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=UTF-8"><title>HttpMessageConverter Demo</title></head><body>    <div id="resp"></div><input type="button" onclick="req();" value="请求"/><script src="assets/js/jquery.js" type="text/javascript"></script><script>    function req(){        $.ajax({            url: "convert",            data: "1-wangyunfei", //数据格式和自定义的消息转换器一致            type:"POST",            contentType:"application/x-wisely", //媒体类型和消息转换器的一致            success: function(data){                $("#resp").html(data);            }        });    }</script></body></html>

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