H2數據庫存儲文件生成方式

testCompact.h3文件生成方式

H2數據庫源碼自帶的測試類TestMVStoreTool

private void testCompact() {
        String fileName = getBaseDir() + "/testCompact.h3";
        FileUtils.createDirectories(getBaseDir());
        //刪除舊的文件
        FileUtils.delete(fileName);
        // store with a very small page size, to make sure
        // there are many leaf pages
        MVStore s = new MVStore.Builder().
                pageSplitSize(1000).
                //調用MVStore的open方法
                               fileName(fileName).autoCommitDisabled().open();
        MVMap<Integer, String> map = s.openMap("data");
        for (int i = 0; i < 10; i++) {
            map.put(i, "Hello World " + i * 10);
            if (i % 3 == 0) {
                s.commit();
            }
        }

public MVStore open() {
            return new MVStore(config);
        }

我們的主要目的是找到創建文件的方法其他的就不看了

 // 19 KB memory is about 1 KB storage
        autoCommitMemory = kb * 1024 * 19;

        o = config.get("autoCompactFillRate");
        autoCompactFillRate = o == null ? 50 : (Integer) o;

        char[] encryptionKey = (char[]) config.get("encryptionKey");
        try {
            if (!fileStoreIsProvided) {
                  //調用了 fileStore的open方法
                fileStore.open(fileName, readOnly, encryptionKey);
            }
            if (fileStore.size() == 0) {
                creationTime = getTimeAbsolute();
                lastCommitTime = creationTime;
                storeHeader.put("H", 2);
                storeHeader.put("blockSize", BLOCK_SIZE);
                storeHeader.put("format", FORMAT_WRITE);
                storeHeader.put("created", creationTime);
                writeStoreHeader();

馬上要到了

 public void open(String fileName, boolean readOnly, char[] encryptionKey) {
        if (file != null) {
            return;
        }
        if (fileName != null) {
            // ensure the Cache file system is registered
            FilePathCache.INSTANCE.getScheme();
            FilePath p = FilePath.get(fileName);
            // if no explicit scheme was specified, NIO is used
            if (p instanceof FilePathDisk &&
                    !fileName.startsWith(p.getScheme() + ":")) {
                // ensure the NIO file system is registered
                //確保NIO文件系統已註冊
                FilePathNio.class.getName();
                fileName = "nio:" + fileName;
            }
        }
        this.fileName = fileName;
        FilePath f = FilePath.get(fileName);
        FilePath parent = f.getParent();
        if (parent != null && !parent.exists()) {
            throw DataUtils.newIllegalArgumentException(
                    "Directory does not exist: {0}", parent);
        }
        if (f.exists() && !f.canWrite()) {
            readOnly = true;
        }
        this.readOnly = readOnly;
        try {
            //真正要創建文件的地方
            file = f.open(readOnly ? "r" : "rw");
            if (encryptionKey != null) {
                byte[] key = FilePathEncrypt.getPasswordBytes(encryptionKey);
                encryptedFile = file;
                file = new FilePathEncrypt.FileEncrypt(fileName, key, file);
            }

好吧就是這裏了RandomAccessFile類關於他的解釋自己去找資料吧

FileNio(String fileName, String mode) throws IOException {
        this.name = fileName;
        //RandomAccessFile 專門處理文件的類
        //創建隨機存儲文件流，文件屬性由參數File對象指定
        channel = new RandomAccessFile(fileName, mode).getChannel();
    }