Spring MVC高级配置-CFANZ编程社区

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

@Override
  public 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

@Bean
  public 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@ResponseBody
public 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
   */
  @Override
  protected 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
   */
  @Override
  protected 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”
   */
  @Override
  protected 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

@Bean
  public MyHttpMessageConverter converter() {
    return new MyHttpMessageConverter();
  }
  
  /**
   * 覆盖掉Spring MVC默认注册的多个HttpMessageConverter
   */
  @Override
  public 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
   */
  @Override
  public 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@ResponseBody
public 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" οnclick="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>