java SSM上传图片到后端(再传到七牛云)教程以及出现的各种异常解决办法

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异常一:Error creating bean with name 'multipartResolver': Failed to introspect bean class

解决办法:在pom.xml添加依赖

<dependency>
 <groupId>commons-fileupload</groupId>
 <artifactId>commons-fileupload</artifactId>
 <version>1.3.1</version>
</dependency>

异常二：MissingServletRequestParameterException:Required: CommonsMultipartFile parameter 'file' is not present

在SpringMVC-Servlet.xml里面增加一个bean字段

<bean id="multipartResolver"
     class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   <!-- 设置上传文件的最大尺寸为10MB 10*1024*1024 -->
   <property name="maxUploadSize">
      <value>10485760</value>
   </property>
</bean>

控制器的方法里要加上@RequestParam(Value="")

public String upload(@RequestParam(value = "file",required = false) CommonsMultipartFile file, HttpSession session)

接着提供七牛云的工具类:

package com.zy.ninepalaceappapi.util;

import com.google.gson.Gson;
import com.qiniu.common.QiniuException;
import com.qiniu.common.Zone;
import com.qiniu.http.Response;
import com.qiniu.storage.BucketManager;
import com.qiniu.storage.Configuration;
import com.qiniu.storage.UploadManager;
import com.qiniu.storage.model.DefaultPutRet;
import com.qiniu.util.Auth;

import java.io.File;

public class QiniuUploadImageUtil {
    //accessKey
    private static String accessKey = "████████████████████████████████████";//用钥匙 刮 屏幕得字符串
    //secretKey
    private static String secretKey ="██████████████████████████████████████████";
    //储存空间名
    private static String bucket ="██████████████████████████████████████████";
    //外链URL前缀
    private static String fronturl = "████████████████████████████████████";


    /**
     * 图片上传

     * @param file  图片路径
     * @return  链接
     * @throws QiniuException
     */
    public static  String  fileUpload(String file)throws QiniuException {
        Auth auth = Auth.create(accessKey,secretKey);
        String upToken = auth.uploadToken(bucket);  //上传凭证
        Configuration cfg = new Configuration(Zone.autoZone());
        UploadManager uploadManager = new UploadManager(cfg);
        String key  = null;
        try {
            Response response = uploadManager.put(file, key, upToken);
            DefaultPutRet putRet = new Gson().fromJson(response.bodyString(),DefaultPutRet.class);
            return fronturl+putRet.key;
        }catch (QiniuException ex){
            Response r = ex.response;
            System.err.println(r.toString());
            try {
                System.err.println(r.bodyString());
            } catch (QiniuException ex2) {
                // ignore
            }
        }
        return null;
    }

    /**
     *删除图片
     * @param key
     * @return
     * @throws QiniuException
     */
    public static String delete(String key)throws QiniuException{
        Auth auth = Auth.create(accessKey,secretKey);
        Configuration cfg = new Configuration(Zone.zone2());
        BucketManager bucketMgr = new BucketManager(auth, cfg);
        try {
            bucketMgr.delete(bucket,key);
        }catch (QiniuException Q){
            return Q.toString();
        }
        System.out.println("success");
        return null;
    }











}

接着控制器的方法:

步骤:

1.由于七牛云工具类的方法是获取图片的本地路径，所以需要一个中转,因此请求参数是MultipartFile类型

2.从前端拿到file对象后先临时储存到项目本地再获取路径

3.调用七牛工具类的上传图片方法传入图片路径

4.最后上传完了就删除本地的那张图片

@ResponseBody
@RequestMapping("uploadImage")
public String upload(@RequestParam(value = "file",required = false) CommonsMultipartFile file, HttpSession session)throws QiniuException{
    try {
        String path = session.getServletContext().getRealPath("/")+file.getOriginalFilename();
        System.out.println(path);
        file.transferTo(new File(path));
        String url =QiniuUploadImageUtil.fileUpload(path);
        File f = new File(path);
        f.delete();
        return url;
    }catch (Exception e){
        return e.toString();
    }
}

最后写一个前端html来上传图片:

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Document</title>
</head>
<body><input type="file" οnchange="aaa()" name=""><img src="https://afp.alicdn.com/afp-creative/creative/u124884735/55308755880f8b637dde1f88b84ea9da.png" οnclick="ButtonClick(this)"><script type="text/javascript">function aaa(e) {let a = document.getElementsByTagName('input')[0].files[0]let b = document.getElementsByTagName('input')[0].valuelet c = new FormData()c.append('file',a)let ajax = new XMLHttpRequest()ajax.open('POST','http://192.168.0.119:8080/shop/uploadImage',true)ajax.send(c)}function ButtonClick(div) { // var div = document.getElementById('divId'); div.contentEditable = 'true'; var controlRange; if (document.body.createControlRange) { controlRange = document.body.createControlRange(); controlRange.addElement(div); controlRange.execCommand('Copy'); } div.contentEditable = 'false'; } </script>
</body>
</html>

最后测试。

上传图片，返回了一个URL

打开链接:

最后附上七牛云的依赖(我也是拷过来的):

<dependency>
 <groupId>com.qiniu</groupId>
 <artifactId>qiniu-java-sdk</artifactId>
 <version>7.2.6</version>
 <scope>compile</scope>
</dependency>
<dependency>
 <groupId>com.squareup.okhttp3</groupId>
 <artifactId>okhttp</artifactId>
 <version>3.3.1</version>
 <scope>compile</scope>
</dependency>
<dependency>
 <groupId>com.google.code.gson</groupId>
 <artifactId>gson</artifactId>
 <version>2.6.2</version>
 <scope>compile</scope>
</dependency>
<dependency>
 <groupId>com.qiniu</groupId>
 <artifactId>happy-dns-java</artifactId>
 <version>0.1.4</version>
 <scope>compile</scope>
</dependency>