文件分片类

jdk/src/main/java/cn/reghao/jutil/jdk/io/FilePart.java

@@ -0,0 +1,93 @@
+package cn.reghao.jutil.jdk.io;
+
+import java.io.*;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * 文件分片
+ *
+ * @author reghao
+ * @date 2023-03-24 10:32:58
+ */
+public class FilePart {
+    private final int partSize;
+
+    public FilePart() {
+        // 10MiB
+        this.partSize = 10*1024*1024;
+    }
+
+    public FilePart(int len) {
+        this.partSize = len*1024*1024;
+    }
+
+    public int getPartSize() {
+        return partSize;
+    }
+
+    public void split(String srcFile, String destDir) throws IOException {
+        File file = new File(srcFile);
+
+        long len = file.length();
+        long total = len/partSize;
+        if (len % partSize != 0) {
+            total += 1;
+        }
+
+        for (int i = 0; i < total; i++) {
+            long start = (long) i*partSize;
+            byte[] part = getPart(file.getAbsolutePath(), partSize, start);
+            if (part.length == 0) {
+                break;
+            }
+
+            String path = destDir + i;
+            File file1  = new File(path);
+            boolean ret = file1.createNewFile();
+            if (!ret) {
+                throw new IOException("创建新文件失败");
+            }
+
+            FileOutputStream fos = new FileOutputStream(file1);
+            fos.write(part);
+            fos.close();
+        }
+    }
+
+    public byte[] getPart(String absolutePath, int partSize, long start) throws IOException {
+        RandomAccessFile raf = new RandomAccessFile(absolutePath, "r");
+        raf.seek(start);
+
+        byte[] buf = new byte[partSize];
+        int readLen = raf.read(buf, 0, partSize);
+        raf.close();
+        if (readLen == -1) {
+            return new byte[0];
+        }
+
+        return readLen == partSize ? buf : Arrays.copyOfRange(buf, 0, readLen);
+    }
+
+    public void merge(String srcDir, String destFile) throws IOException {
+        File dir = new File(srcDir);
+        List<File> list = Arrays.asList(Objects.requireNonNull(dir.listFiles()));
+        list.sort((o1, o2) -> {
+            Integer o1name = Integer.parseInt(o1.getName());
+            Integer o2name = Integer.parseInt(o2.getName());
+            return o1name.compareTo(o2name);
+        });
+
+        long start = 0;
+        RandomAccessFile raf = new RandomAccessFile(destFile, "rw");
+        for (File file : list) {
+            long length = file.length();
+            FileInputStream fis = new FileInputStream(file);
+            raf.seek(start);
+            raf.write(fis.readAllBytes());
+            start += length;
+        }
+        raf.close();
+    }
+}