Readable.java

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package java.lang;

import java.io.IOException;

/**
 * A {@code Readable} is a source of characters.
 * Characters from a {@code Readable} are made available to callers of the read method via a {@link java.nio.CharBuffer CharBuffer}.
 *
 * @since 1.5
 */
// 从Readable容器读取数据，写入到目标缓冲区
public interface Readable {
    
    /**
     * Attempts to read characters into the specified character buffer.
     * The buffer is used as a repository of characters as-is: the only
     * changes made are the results of a put operation. No flipping or
     * rewinding of the buffer is performed.
     *
     * @param cb the buffer to read characters into
     *
     * @return The number of {@code char} values added to the buffer,
     * or -1 if this source of characters is at its end
     *
     * @throws IOException                      if an I/O error occurs
     * @throws NullPointerException             if cb is null
     * @throws java.nio.ReadOnlyBufferException if cb is a read only buffer
     */
    // 读取此容器的内容，并写入目标缓冲区cb（如果放不下，则只写入放得下的部分）
    int read(java.nio.CharBuffer cb) throws IOException;
}