一、前言

关于apache的commons-io源码包org.apache.commons.io.input.BrokenInputStream、org.apache.commons.io.input.NullReader、org.apache.commons.io.ClassLoaderObjectInputStream、org.apache.commons.io.NullReader等根据场景自定义方式，详情如下。

二、源码说明

1.BrokenInputStream类

package org.apache.commons.io.input;@b@@b@import java.io.IOException;@b@import java.io.InputStream;@b@@b@public class BrokenInputStream extends InputStream@b@{@b@  private final IOException exception;@b@@b@  public BrokenInputStream(IOException exception)@b@  {@b@    this.exception = exception;@b@  }@b@@b@  public BrokenInputStream()@b@  {@b@    this(new IOException("Broken input stream"));@b@  }@b@@b@  public int read()@b@    throws IOException@b@  {@b@    throw this.exception;@b@  }@b@@b@  public int available()@b@    throws IOException@b@  {@b@    throw this.exception;@b@  }@b@@b@  public long skip(long n)@b@    throws IOException@b@  {@b@    throw this.exception;@b@  }@b@@b@  public void reset()@b@    throws IOException@b@  {@b@    throw this.exception;@b@  }@b@@b@  public void close()@b@    throws IOException@b@  {@b@    throw this.exception;@b@  }@b@}

2.ClassLoaderObjectInputStream类

package org.apache.commons.io.input;@b@@b@import java.io.IOException;@b@import java.io.InputStream;@b@import java.io.ObjectInputStream;@b@import java.io.ObjectStreamClass;@b@import java.io.StreamCorruptedException;@b@import java.lang.reflect.Proxy;@b@@b@public class ClassLoaderObjectInputStream extends ObjectInputStream@b@{@b@  private final ClassLoader classLoader;@b@@b@  public ClassLoaderObjectInputStream(ClassLoader classLoader, InputStream inputStream)@b@    throws IOException, StreamCorruptedException@b@  {@b@    super(inputStream);@b@    this.classLoader = classLoader;@b@  }@b@@b@  protected Class<?> resolveClass(ObjectStreamClass objectStreamClass)@b@    throws IOException, ClassNotFoundException@b@  {@b@    Class clazz = Class.forName(objectStreamClass.getName(), false, this.classLoader);@b@@b@    if (clazz != null)@b@    {@b@      return clazz;@b@    }@b@@b@    return super.resolveClass(objectStreamClass);@b@  }@b@@b@  protected Class<?> resolveProxyClass(String[] interfaces)@b@    throws IOException, ClassNotFoundException@b@  {@b@    Class[] interfaceClasses = new Class[interfaces.length];@b@    for (int i = 0; i < interfaces.length; ++i)@b@      interfaceClasses[i] = Class.forName(interfaces[i], false, this.classLoader);@b@    try@b@    {@b@      return Proxy.getProxyClass(this.classLoader, interfaceClasses); } catch (IllegalArgumentException e) {@b@    }@b@    return super.resolveProxyClass(interfaces);@b@  }@b@}

3.NullInputStream/NullReader等

package org.apache.commons.io.input;@b@@b@import java.io.EOFException;@b@import java.io.IOException;@b@import java.io.InputStream;@b@@b@public class NullInputStream extends InputStream@b@{@b@  private final long size;@b@  private long position;@b@  private long mark;@b@  private long readlimit;@b@  private boolean eof;@b@  private final boolean throwEofException;@b@  private final boolean markSupported;@b@@b@  public NullInputStream(long size)@b@  {@b@    this(size, true, false);@b@  }@b@@b@  public NullInputStream(long size, boolean markSupported, boolean throwEofException)@b@  {@b@    this.mark = -1L;@b@@b@    this.size = size;@b@    this.markSupported = markSupported;@b@    this.throwEofException = throwEofException;@b@  }@b@@b@  public long getPosition()@b@  {@b@    return this.position;@b@  }@b@@b@  public long getSize()@b@  {@b@    return this.size;@b@  }@b@@b@  public int available()@b@  {@b@    long avail = this.size - this.position;@b@    if (avail <= 0L)@b@      return 0;@b@    if (avail > 2147483647L)@b@      return 2147483647;@b@@b@    return (int)avail;@b@  }@b@@b@  public void close()@b@    throws IOException@b@  {@b@    this.eof = false;@b@    this.position = 0L;@b@    this.mark = -1L;@b@  }@b@@b@  public synchronized void mark(int readlimit)@b@  {@b@    if (!(this.markSupported))@b@      throw new UnsupportedOperationException("Mark not supported");@b@@b@    this.mark = this.position;@b@    this.readlimit = readlimit;@b@  }@b@@b@  public boolean markSupported()@b@  {@b@    return this.markSupported;@b@  }@b@@b@  public int read()@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Read after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += 1L;@b@    return processByte();@b@  }@b@@b@  public int read(byte[] bytes)@b@    throws IOException@b@  {@b@    return read(bytes, 0, bytes.length);@b@  }@b@@b@  public int read(byte[] bytes, int offset, int length)@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Read after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += length;@b@    int returnLength = length;@b@    if (this.position > this.size) {@b@      returnLength = length - (int)(this.position - this.size);@b@      this.position = this.size;@b@    }@b@    processBytes(bytes, offset, returnLength);@b@    return returnLength;@b@  }@b@@b@  public synchronized void reset()@b@    throws IOException@b@  {@b@    if (!(this.markSupported))@b@      throw new UnsupportedOperationException("Mark not supported");@b@@b@    if (this.mark < 0L)@b@      throw new IOException("No position has been marked");@b@@b@    if (this.position > this.mark + this.readlimit) {@b@      throw new IOException("Marked position [" + this.mark + "] is no longer valid - passed the read limit [" + this.readlimit + "]");@b@    }@b@@b@    this.position = this.mark;@b@    this.eof = false;@b@  }@b@@b@  public long skip(long numberOfBytes)@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Skip after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += numberOfBytes;@b@    long returnLength = numberOfBytes;@b@    if (this.position > this.size) {@b@      returnLength = numberOfBytes - this.position - this.size;@b@      this.position = this.size;@b@    }@b@    return returnLength;@b@  }@b@@b@  protected int processByte()@b@  {@b@    return 0;@b@  }@b@@b@  protected void processBytes(byte[] bytes, int offset, int length)@b@  {@b@  }@b@@b@  private int doEndOfFile()@b@    throws EOFException@b@  {@b@    this.eof = true;@b@    if (this.throwEofException)@b@      throw new EOFException();@b@@b@    return -1;@b@  }@b@}

package org.apache.commons.io.input;@b@@b@import java.io.EOFException;@b@import java.io.IOException;@b@import java.io.Reader;@b@@b@public class NullReader extends Reader@b@{@b@  private final long size;@b@  private long position;@b@  private long mark;@b@  private long readlimit;@b@  private boolean eof;@b@  private final boolean throwEofException;@b@  private final boolean markSupported;@b@@b@  public NullReader(long size)@b@  {@b@    this(size, true, false);@b@  }@b@@b@  public NullReader(long size, boolean markSupported, boolean throwEofException)@b@  {@b@    this.mark = -1L;@b@@b@    this.size = size;@b@    this.markSupported = markSupported;@b@    this.throwEofException = throwEofException;@b@  }@b@@b@  public long getPosition()@b@  {@b@    return this.position;@b@  }@b@@b@  public long getSize()@b@  {@b@    return this.size;@b@  }@b@@b@  public void close()@b@    throws IOException@b@  {@b@    this.eof = false;@b@    this.position = 0L;@b@    this.mark = -1L;@b@  }@b@@b@  public synchronized void mark(int readlimit)@b@  {@b@    if (!(this.markSupported))@b@      throw new UnsupportedOperationException("Mark not supported");@b@@b@    this.mark = this.position;@b@    this.readlimit = readlimit;@b@  }@b@@b@  public boolean markSupported()@b@  {@b@    return this.markSupported;@b@  }@b@@b@  public int read()@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Read after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += 1L;@b@    return processChar();@b@  }@b@@b@  public int read(char[] chars)@b@    throws IOException@b@  {@b@    return read(chars, 0, chars.length);@b@  }@b@@b@  public int read(char[] chars, int offset, int length)@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Read after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += length;@b@    int returnLength = length;@b@    if (this.position > this.size) {@b@      returnLength = length - (int)(this.position - this.size);@b@      this.position = this.size;@b@    }@b@    processChars(chars, offset, returnLength);@b@    return returnLength;@b@  }@b@@b@  public synchronized void reset()@b@    throws IOException@b@  {@b@    if (!(this.markSupported))@b@      throw new UnsupportedOperationException("Mark not supported");@b@@b@    if (this.mark < 0L)@b@      throw new IOException("No position has been marked");@b@@b@    if (this.position > this.mark + this.readlimit) {@b@      throw new IOException("Marked position [" + this.mark + "] is no longer valid - passed the read limit [" + this.readlimit + "]");@b@    }@b@@b@    this.position = this.mark;@b@    this.eof = false;@b@  }@b@@b@  public long skip(long numberOfChars)@b@    throws IOException@b@  {@b@    if (this.eof)@b@      throw new IOException("Skip after end of file");@b@@b@    if (this.position == this.size)@b@      return doEndOfFile();@b@@b@    this.position += numberOfChars;@b@    long returnLength = numberOfChars;@b@    if (this.position > this.size) {@b@      returnLength = numberOfChars - this.position - this.size;@b@      this.position = this.size;@b@    }@b@    return returnLength;@b@  }@b@@b@  protected int processChar()@b@  {@b@    return 0;@b@  }@b@@b@  protected void processChars(char[] chars, int offset, int length)@b@  {@b@  }@b@@b@  private int doEndOfFile()@b@    throws EOFException@b@  {@b@    this.eof = true;@b@    if (this.throwEofException)@b@      throw new EOFException();@b@@b@    return -1;@b@  }@b@}