20240229

事务与代理对象

在java中，若@Transactional事务注解要生效，则被注解的方法需在代理对象内，对于service层中的接口实现类，不是代理对象，而service接口为代理对象，要使接口实现类的函数能使用事务，则需将该方法暴露在service接口中，并注入对应的service接口，例子如下：

 //接口实现类
 @Service
 public class service1Impl implements Service1{
	@Autowired
	Service1 service1;
	
	public void function1(){
		int a = 1;
		//此时需要执行事务的function2通过代理对象调用的，事务生效
		service1.service2(a);
	}
	
	@Override
 	@Transactional
	public void function2(int a){
		System.out.println(a);
		...执行数据库操作等
	}
}
//接口

public interface Service1 {
	public void function2(int a)；//将实现类暴露在接口中
}

文件分块

将一个文件分块

public void testChunk() throws IOException {
		//源文件
        File sourceFile = new File("d:/TestBigFile/source/test1.mp4");
		//存储分块的位置
        String chunkPath = "d:/TestBigFile/chunk/";
        File chunkFolder = new File(chunkPath);
        if (!chunkFolder.exists()) {
            chunkFolder.mkdirs();
        }
        //分块大小(minio合并时单块最小为5MB)
        long chunkSize = 1024 * 1024 * 5;
        //分块数量
        long chunkNum = (long) Math.ceil(sourceFile.length() * 1.0 / chunkSize);
        System.out.println("分块总数："+chunkNum);
        //缓冲区大小
        byte[] b = new byte[1024];
        //使用RandomAccessFile访问文件
        RandomAccessFile raf_read = new RandomAccessFile(sourceFile, "r");
        //分块
        for (int i = 0; i < chunkNum; i++) {
            //创建分块文件
            File file = new File(chunkPath + i);
            if(file.exists()){
                file.delete();
            }
            boolean newFile = file.createNewFile();
            if (newFile) {
                //向分块文件中写数据
                RandomAccessFile raf_write = new RandomAccessFile(file, "rw");
                int len = -1;
                while ((len = raf_read.read(b)) != -1) {
                    raf_write.write(b, 0, len);
                    //块的大小超过了约定的大小
                    if (file.length() >= chunkSize) {
                        break;
                    }
                }
                raf_write.close();
                System.out.println("完成分块"+i);
            }

        }
        raf_read.close();
    }

合并分块

public void testMerge() throws IOException {
        //块文件目录
        File chunkFolder = new File("d:/TestBigFile/chunk/");
        //原始文件
        File originalFile = new File("d:/TestBigFile/source/test1.mp4");
        //合并文件
        File mergeFile = new File("d:/TestBigFile/source/test2.mp4");
        if (mergeFile.exists()) {
            mergeFile.delete();
        }
        //创建新的合并文件
        mergeFile.createNewFile();
        //用于写文件
        RandomAccessFile raf_write = new RandomAccessFile(mergeFile, "rw");
        //指针指向文件顶端
        raf_write.seek(0);
        //缓冲区
        byte[] b = new byte[1024];
        //分块列表
        File[] fileArray = chunkFolder.listFiles();
        // 转成集合，便于排序
        List<File> fileList = Arrays.asList(fileArray);
        // 从小到大排序
        Collections.sort(fileList, new Comparator<File>() {
            @Override
            public int compare(File o1, File o2) {
                return Integer.parseInt(o1.getName()) - Integer.parseInt(o2.getName());
            }
        });
        //合并文件
        for (File chunkFile : fileList) {
            RandomAccessFile raf_read = new RandomAccessFile(chunkFile, "rw");
            int len = -1;
            while ((len = raf_read.read(b)) != -1) {
                raf_write.write(b, 0, len);

            }
            raf_read.close();
        }
        raf_write.close();
  }

minio初始化

 static MinioClient minioClient =
            MinioClient.builder()
                    .endpoint("http://127.0.0.1:9000")
                    .credentials("minioadmin", "minioadmin")
                    .build();

将分块上传到minio(上传的为上述已分块的文件分块，共7块)

public void chunkUpload() throws IOException, ServerException, InsufficientDataException, ErrorResponseException, NoSuchAlgorithmException, InvalidKeyException, InvalidResponseException, XmlParserException, InternalException {
        String filePath = "d:/TestBigFile/chunk/";
        for(int i = 0; i < 7; i++){
            //文件信息
            UploadObjectArgs testbucket = UploadObjectArgs.builder()
                    .bucket("testbucket")
                    .object("chunk/" + i)//添加子目录
                    .filename(filePath + i)
                    .build();
            //上传文件
            minioClient.uploadObject(testbucket);
            System.out.println("分块" + i + "上传成功");
        }
    }

将minio上的分块合并

public void MergeMinio() throws IOException, ServerException, InsufficientDataException, ErrorResponseException, NoSuchAlgorithmException, InvalidKeyException, InvalidResponseException, XmlParserException, InternalException {
        //获取各个分块
        List<ComposeSource> list = new ArrayList<>();
        for(int i = 0; i < 7; i++){
            ComposeSource composeSource = ComposeSource.builder()
                    .bucket("testbucket")
                    .object("chunk/" + i)
                    .build();
            list.add(composeSource);
        }

        ComposeObjectArgs composeObjectArgs = ComposeObjectArgs.builder()
                .bucket("testbucket")
                .object("test1.mp4")
                .sources(list)//分块列表
                .build();
		//执行合并
        minioClient.composeObject(composeObjectArgs);
    }