版本

  <dependency>  
<groupId>org.springframework.data</groupId>  
<artifactId>spring-data-mongodb</artifactId>  
<version>2.1.3.RELEASE</version>  

使用的时候注意版本，2.x以上某些方法进行了更改。gridfs下载在2.x以下版本为

private static void download() {  
    GridFSDBFile fs = gridFsTemplate.findOne(Query.query(Criteria.where("\_id").is("58da69a45aa6c70234eb70f1")));  
    try {  
        fs.writeTo("/home/a.txt");  
    } catch (IOException e) {  
        e.printStackTrace();  
    }  
}

2.x以上版本。find的返回值进行了更改。需要使用如下方法进行下载

find找到fs后，调用

getResource方法。然后进行java的文件存储。

private static void download() {
GridFSFile fs = gridFsTemplate.findOne(Query.query(Criteria.where("_id").is("5c0619774a24a3408284b4b3")));
GridFsResource gs = gridFsTemplate.getResource(fs);
OutputStream os = null;
try {
byte[] bs = new byte[1024];
int len;
InputStream in = gs.getInputStream();
File file = new File("/home/chaoba/");
os = new FileOutputStream(file.getPath() + File.separator + gs.getFilename());
while ((len = in.read(bs)) != -1) {
os.write(bs, 0, len);
}
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

上传方法

private static void upload() {

    File file = new File("/home/chaoba/Downloads/抖音-日版.apk");  
    try {  
        ObjectId id = gridFsTemplate.store(new FileInputStream(file), file.getName(),  
                new Document().put("user", "admin"));  
        System.out.println(id);

    } catch (FileNotFoundException e) {  
        e.printStackTrace();  
    }

}