java文件的读写-优快云博客

本文提供了几个实用的Java代码片段，用于处理文件读写及转换等常见任务。其中包括从字节数组创建文件、将文件内容读取为字节数组、直接写入字节数组到文件以及从输入流中获取字节数组的方法。

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public File getFileFromBytes(byte[] b, String outputFile){
		BufferedOutputStream stream = null; 
        File file = null; 
        try{ 
            file = new File(outputFile); 
            FileOutputStream fstream = new FileOutputStream(file); 
            stream = new BufferedOutputStream(fstream); 
            stream.write(b); 
        } catch (Exception e){ 
            e.printStackTrace(); 
        } finally{ 
            if (stream != null){ 
                try{ 
                    stream.close(); 
                } catch (IOException e1){ 
                    e1.printStackTrace(); 
                } 
            } 
        } 
        return file; 

	}

Java代码

public static ByteArrayOutputStream readFile(String filename) {
try {
FileInputStream fileInStream = new FileInputStream(filename);
ByteArrayOutputStream fileByteStream = new ByteArrayOutputStream();
int i = 0;
while ((i = fileInStream.read()) != -1) {
fileByteStream.write(i);
}
fileInStream.close();
return fileByteStream;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static void writeFile(String fileName, byte[] data) {
try {
FileOutputStream fos = new FileOutputStream(fileName);
fos.write(data);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
//transfor InputStream to byte
public static byte[] getBytes(InputStream is) throws Exception {
byte[] data = null;
Collection chunks = new ArrayList();
byte[] buffer = new byte[1024 * 1000];
int read = -1;
int size = 0;
while ((read = is.read(buffer)) != -1) {
if (read > 0) {
byte[] chunk = new byte[read];
System.arraycopy(buffer, 0, chunk, 0, read);
chunks.add(chunk);
size += chunk.length;
}
}
if (size > 0) {
ByteArrayOutputStream bos = null;
try {
bos = new ByteArrayOutputStream(size);
for (Iterator itr = chunks.iterator(); itr.hasNext();) {
byte[] chunk = (byte[]) itr.next();
bos.write(chunk);
}
data = bos.toByteArray();
} finally {
if (bos != null) {
bos.close();
}
}
}
return data;
}