全面了解java byte数组与文件读写
全面了解java byte数组与文件读写
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class FileHelper {
<span style="white-space:pre"> </span>//第一种获取文件内容方式
public byte[] getContent(String filePath) throws IOException {
File file = new File(filePath);
long fileSize = file.length();
if (fileSize > Integer.MAX_VALUE) {
System.out.println("file too big...");
return null;
}
FileInputStream fi = new FileInputStream(file);
byte[] buffer = new byte[(int) fileSize];
int offset = 0;
int numRead = 0;
while (offset < buffer.length
&& (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {
offset += numRead;
}
// 确保所有数据均被读取
if (offset != buffer.length) {
throw new IOException("Could not completely read file "
+ file.getName());
}
fi.close();
return buffer;
}
//第二种获取文件内容方式
public byte[] getContent2(String filePath) throws IOException
{
FileInputStream in=new FileInputStream(filePath);
ByteArrayOutputStream out=new ByteArrayOutputStream(1024);
System.out.println("bytes available:"+in.available());
byte[] temp=new byte[1024];
int size=0;
while((size=in.read(temp))!=-1)
{
out.write(temp,0,size);
}
in.close();
byte[] bytes=out.toByteArray();
System.out.println("bytes size got is:"+bytes.length);
return bytes;
}
//将byte数组写入文件
public void createFile(String path, byte[] content) throws IOException {
FileOutputStream fos = new FileOutputStream(path);
fos.write(content);
fos.close();
}
}
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