fix code

hutool-core/src/main/java/org/dromara/hutool/core/io/FastStringReader.java

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2023 looly(loolly@aliyun.com)
+ * Hutool is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *          http://license.coscl.org.cn/MulanPSL2
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+
+package org.dromara.hutool.core.io;
+
+import java.io.IOException;
+import java.io.Reader;
+
+/**
+ * 快速字符串读取，相比jdk的StringReader非线程安全，速度更快。
+ *
+ * @author looly
+ */
+public class FastStringReader extends Reader {
+
+	private String str;
+	private final int length;
+
+	private int next = 0;
+	private int mark = 0;
+
+	/**
+	 * 构造
+	 *
+	 * @param s 供读取的String
+	 */
+	public FastStringReader(final String s) {
+		this.str = s;
+		this.length = s.length();
+	}
+
+	/**
+	 * 读取单个字符
+	 *
+	 * @return 读取的字符, -1表示读取结束
+	 * @throws IOException IO异常
+	 */
+	@Override
+	public int read() throws IOException {
+		ensureOpen();
+		if (next >= length) {
+			return -1;
+		}
+		return str.charAt(next++);
+	}
+
+	/**
+	 * 将多个字符读取到提供的字符数组中
+	 *
+	 * @param charBuffer 目标buffer
+	 * @param off        开始位置
+	 * @param len        读取最大长度
+	 * @return 读取的字符长度, -1表示读取到了末尾
+	 * @throws IOException IO异常
+	 */
+	@Override
+	public int read(final char[] charBuffer, final int off, final int len) throws IOException {
+		ensureOpen();
+		if ((off < 0) || (off > charBuffer.length) || (len < 0) ||
+			((off + len) > charBuffer.length) || ((off + len) < 0)) {
+			throw new IndexOutOfBoundsException();
+		}
+
+		if (len == 0) {
+			return 0;
+		}
+		if (next >= length) {
+			return -1;
+		}
+
+		final int n = Math.min(length - next, len);
+		str.getChars(next, next + n, charBuffer, off);
+		next += n;
+		return n;
+	}
+
+	/**
+	 * 跳过指定长度，返回跳过的字符数。
+	 *
+	 * <p>{@code ns} 参数可能为负数, 负数表示向前跳过，跳到开头则停止
+	 *
+	 * <p>如果字符串所有字符被读取或跳过, 此方法无效，始终返回0.
+	 *
+	 * @throws IOException IO异常
+	 */
+	@Override
+	public long skip(final long ns) throws IOException {
+		ensureOpen();
+		if (next >= length){
+			return 0;
+		}
+
+		// Bound skip by beginning and end of the source
+		long n = Math.min(length - next, ns);
+		n = Math.max(-next, n);
+		next += n;
+		return n;
+	}
+
+	@Override
+	public boolean ready() throws IOException {
+		ensureOpen();
+		return true;
+	}
+
+	@Override
+	public boolean markSupported() {
+		return true;
+	}
+
+	@Override
+	public void mark(final int readAheadLimit) throws IOException {
+		if (readAheadLimit < 0) {
+			throw new IllegalArgumentException("Read-ahead limit < 0");
+		}
+		ensureOpen();
+		mark = next;
+	}
+
+	@Override
+	public void reset() throws IOException {
+		ensureOpen();
+		next = mark;
+	}
+
+	@Override
+	public void close() {
+		str = null;
+	}
+
+	/**
+	 * Check to make sure that the stream has not been closed
+	 */
+	private void ensureOpen() throws IOException {
+		if (str == null){
+			throw new IOException("Stream closed");
+		}
+	}
+}