文件上传的步骤：
1、创建ServerSocket
2、调用accept获得客户端Socket
3、定义字节数组
4、创建文件输出流，获得客户端输入流
5、循环读取输入流的字节，写入到文件输出流
1、创建Socket
2、获得socket对象输出流
3、创建文件输入流
4、循环读取文件输入流字节，写入到输出流
服务器端：
public class FileServer {
public static final int PORT = 8888;
public static final String PATH = "D:\\upload\\";
public void start(){
System.out.println("start...");
try ( //创建服务器端对象
ServerSocket server = new ServerSocket(PORT);){
while (true){
Socket socket = server.accept();
try ( //创建文件输出流和网络输入流
DataInputStream in = new DataInputStream(socket.getInputStream());
//读取哭护短发来的文件名，创建文件输出流
FileOutputStream out = new FileOutputStream(PATH+in.readUTF())){
int len = 0;
byte[] buffer = new byte[1024];
while ((len = in.read(buffer)) != -1){
out.write(buffer,0,len);
}
System.out.println("服务器保存完毕！");
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new FileServer().start();
}
}客户端：
public class FileClient {
/**
* 发送文件
*/
public void sendFile(String ip,int port,String path){
File file = new File(path);
try (
//创建连接，创建文件输入流，网络输出流
Socket socket = new Socket(ip,port);
InputStream in = new FileInputStream(path);
DataOutputStream out = new DataOutputStream(socket.getOutputStream())){
//先发送文件给服务器
out.writeUTF(file.getName());
out.flush();
//读取本地文件，写入到网络输出流中
int len = 0;
byte[] buffer = new byte[1024];
while ((len = in.read(buffer)) != -1){
out.write(buffer,0,len);
}
System.out.println("客户端发送完毕！");
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new FileClient().sendFile("192.168.31.226",8888,"C:\\Users\\admin\\Desktop\\C.txt");
}
}实现效果：
