Java FileOutputStream删除文件的内容
嗨,我正在尝试使用FileOutputStream通过网络发送数据。无论何时使用链接的文件创建FileOutputStream,它都会删除找到的所有数据,就好像用新文件替换旧文件一样 有人能帮忙吗?这是密码Java FileOutputStream删除文件的内容,java,sockets,fileoutputstream,Java,Sockets,Fileoutputstream,嗨,我正在尝试使用FileOutputStream通过网络发送数据。无论何时使用链接的文件创建FileOutputStream,它都会删除找到的所有数据,就好像用新文件替换旧文件一样 有人能帮忙吗?这是密码 File videoFile = new File (Current_video_file); log.info(videoFile.toString()); InputStream is = null; OutputStream outS = null; try{ is =
File videoFile = new File (Current_video_file);
log.info(videoFile.toString());
InputStream is = null;
OutputStream outS = null;
try{
is = socket.getInputStream();
} catch (IOException e){
e.printStackTrace();
}
try{
outS = new FileOutputStream(videoFile);
} catch (IOException e){
e.printStackTrace();
}
byte [] videoLength = new byte [16*1024];
log.info("About to send");
int count;
while((count = is.read(videoLength)) > 0){
log.info("Sending Message");
outS.write(videoLength, 0, count);
}
log.info("Data Sent");
outS.close();
is.close();
FileOutputStream的构造函数还有第二个参数可用。如果为true,它将在文件末尾附加您的数据;如果为false,它将替换内容。默认情况下为false 因此,您只需更改FileOutputStream的声明:
outS = new FileOutputStream(videoFile, true);
FileOutputStream的构造函数还有第二个参数可用。如果为true,它将在文件末尾附加您的数据;如果为false,它将替换内容。默认情况下为false 因此,您只需更改FileOutputStream的声明:
outS = new FileOutputStream(videoFile, true);
JavaDoc说:
/**
* Creates a file output stream to write to the file represented by
* the specified <code>File</code> object. If the second argument is
* <code>true</code>, then bytes will be written to the end of the file
* rather than the beginning. A new <code>FileDescriptor</code> object is
* created to represent this file connection.
* <p>
* First, if there is a security manager, its <code>checkWrite</code>
* method is called with the path represented by the <code>file</code>
* argument as its argument.
* <p>
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a <code>FileNotFoundException</code> is thrown.
*
* @param file the file to be opened for writing.
* @param append if <code>true</code>, then bytes will be written
* to the end of the file rather than the beginning
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason
* @exception SecurityException if a security manager exists and its
* <code>checkWrite</code> method denies write access
* to the file.
* @see java.io.File#getPath()
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @since 1.4
*/
public FileOutputStream(File file, boolean append)
因此,要使用它,您应该向FileOutputStream的构造函数添加一个布尔值,True表示追加,False表示覆盖
因此,您的代码应该如下所示:
Boolean append = true;
outS = new FileOutputStream(videoFile, append);
JavaDoc说:
/**
* Creates a file output stream to write to the file represented by
* the specified <code>File</code> object. If the second argument is
* <code>true</code>, then bytes will be written to the end of the file
* rather than the beginning. A new <code>FileDescriptor</code> object is
* created to represent this file connection.
* <p>
* First, if there is a security manager, its <code>checkWrite</code>
* method is called with the path represented by the <code>file</code>
* argument as its argument.
* <p>
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a <code>FileNotFoundException</code> is thrown.
*
* @param file the file to be opened for writing.
* @param append if <code>true</code>, then bytes will be written
* to the end of the file rather than the beginning
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason
* @exception SecurityException if a security manager exists and its
* <code>checkWrite</code> method denies write access
* to the file.
* @see java.io.File#getPath()
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @since 1.4
*/
public FileOutputStream(File file, boolean append)
因此,要使用它,您应该向FileOutputStream的构造函数添加一个布尔值,True表示追加,False表示覆盖
因此,您的代码应该如下所示:
Boolean append = true;
outS = new FileOutputStream(videoFile, append);
提示:你可以自己动手;例如,开始阅读javadoc以获取您想要使用的库类/方法。换句话说:你假设这个或那个应该如何运作。事实是:现实并不在乎你的假设。这并不意味着粗鲁,但对程序员来说是一个重要的教训:始终验证您的想法以及其他组件的实际行为。特别是当它有很好的文档记录时,这一部分真的很容易;例如,开始阅读javadoc以获取您想要使用的库类/方法。换句话说:你假设这个或那个应该如何运作。事实是:现实并不在乎你的假设。这并不意味着粗鲁,但对程序员来说是一个重要的教训:始终验证您的想法以及其他组件的实际行为。尤其是当它有很好的文档记录时,这一部分真的很容易。