java io （二） InputStream

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InputStream源码分析

本源码基于jdk 1.8.0_102
package java.io;import java.io.Closeable;public abstract class InputStream implements Closeable {// 允许skip的最大字节数private static final int MAX_SKIP_BUFFER_SIZE = 2048;public abstract int read() throws IOException; //将数据读入字节数组中public int read(byte[] arg0) throws IOException {    return this.read(arg0, 0, arg0.length);} // 第一个参数是数据要读入的数组，第二个参数是读取的起点，第三个是读取的节 //数public int read(byte[] arg0, int arg1, int arg2) throws IOException {    if (arg0 == null) {        throw new NullPointerException();    } else if (arg1 >= 0 && arg2 >= 0 && arg2 <= arg0.length - arg1) {        if (arg2 == 0) {            return 0;        } else {            int arg3 = this.read();            if (arg3 == -1) {                return -1;            } else {                arg0[arg1] = (byte) arg3;                int arg4 = 1;                try {                    while (arg4 < arg2) {                        arg3 = this.read();                        //如果读取的字节是-1,表示读取完毕                        if (arg3 == -1) {                            break;                        }      // arg4 是标记,每读取一次就将读取的字节放到字节数组中                        arg0[arg1 + arg4] = (byte) arg3;                        ++arg4;                    }                } catch (IOException arg6) {                    ;                }                return arg4;            }        }    } else {        throw new IndexOutOfBoundsException();    }} // 跳过输入流中的n个字节public long skip(long arg0) throws IOException {    long arg2 = arg0;    if (arg0 <= 0L) {        return 0L;    } else {        int arg5 = (int) Math.min(2048L, arg0);          // arg4 是已经读取的字节数        int arg4;         for (byte[] arg6 = new byte[arg5]; arg2 > 0L; arg2 -= (long) arg4) {            arg4 = this.read(arg6, 0, (int) Math.min((long) arg5, arg2));            if (arg4 < 0) {                break;            }        }          // 正常退出会返回arg0,即传入的要跳过的字节数        return arg0 - arg2;    }}public int available() throws IOException {    return 0;}public void close() throws IOException {}public synchronized void mark(int arg0) {}public synchronized void reset() throws IOException {    throw new IOException("mark/reset not supported");} //是否支持标记public boolean markSupported() {    return false;}
}
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