net.wicp.tams.common.io.InputStreamRamdomRead Maven / Gradle / Ivy
package net.wicp.tams.common.io;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
/***
* 只读的方式打开文件，自由读
*
* @author zhoujunhui
*
*/
public class InputStreamRamdomRead extends InputStream {
//
private final RandomAccessFile file;
protected final File oriFile;
public InputStreamRamdomRead(File file) throws IOException {
this.file = new RandomAccessFile(file, "r");
this.oriFile = file;
}
/***
* 还有多少可字节可用
*/
@Override
public int available() throws IOException {
final long fp = this.file.getFilePointer();
return (int) (this.file.length() - fp);
}
@Override
public void close() throws IOException {
this.file.close();
}
@Override
public int read() throws IOException {
return this.file.read();
}
@Override
public int read(byte b[], int off, int len) throws IOException {
return this.file.read(b, off, len);
}
@Override
public boolean markSupported() {
return true;
}
protected long markPos = -1l;
@Override
public synchronized void mark(int readlimit) {
try {
markPos = this.file.getFilePointer();
} catch (IOException e) {
markPos = -1;
}
}
@Override
public synchronized void reset() throws IOException {
if (markPos >= 0) {
this.file.seek(markPos);
}
}
/**
* 得到当前位置
*
* @return 当前位置
*/
public long getCurPos() {
try {
return this.file.getFilePointer();
} catch (IOException e) {
return -1;
}
}
public void seek(long pos) throws IOException {
file.seek(pos);
}
// //////////
// ////////////////////////////////////////下面是一些扩展方法////////////////////////////////////////////////////////////////////////////
public byte[] readBytes(int length) throws IOException {
final byte[] r = new byte[length];
this.read(r, 0, length);
return r;
}
public byte readByte() throws IOException {
return readBytes(1)[0];
}
}