Java复制二进制文件前后数据不完全一致

Question

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class TestClass {

public static void main(String[] args) throws IOException {
    FileInputStream in = new FileInputStream(new File("F:/360Downloads/LoginAction.class"));
    FileOutputStream out = new FileOutputStream(new File("F:/LoginAction.class"));
    byte[] temp = new byte[1024];
    while(in.read(temp)!=-1){
        out.write(temp);
    }

// out.flush();
in.close();
out.close();
System.out.println("---------------");
}
}
代码其实很简单，就是用java复制二进制文件。我用BCompare.exe比较一下，发现复制后的文件末尾多了一段数据，不知道是什么东西，如何保证复制前后文件二进制数据一模一样？也请解释一下采用上述代码，多出来的那段是什么东西。谢谢！

Answer 1

[quote]while(in.read(temp)!=-1){
out.write(temp);
} [/quote]

[code="java"]
int len;

while((len=in.read(temp))!=-1){
out.write(temp,0,len);
}

[/code]