Advanced API (local simulation download file)

Realize wireless chat between client and server

System.out.println("============= Server side ===============");
        // Turn on the server
        ServerSocket ss = new ServerSocket(7979);
        // Waiting for client connections
        Socket sk = ss.accept();
        System.out.println(" Connected ");

        // Input stream Read the message sent by the client
        InputStream is = sk.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);

        // Resource path
        String readLine = br.readLine();

        // File
        File file = new File(readLine);
        FileInputStream fis = null;
        InputStreamReader isr2 = null;
        BufferedReader br2 = null;

        // Write into the network
        OutputStream os = sk.getOutputStream();
        OutputStreamWriter osw = new OutputStreamWriter(os);
        BufferedWriter bw = new BufferedWriter(osw);

        if (file.exists()) {// There is
            // Read the contents of the specified resource in the server
            fis = new FileInputStream(file);
            isr2 = new InputStreamReader(fis);
            br2 = new BufferedReader(isr2);
            String str = "";
            while (null != (str = br2.readLine())) {
                bw.write(str);
                bw.newLine();
                bw.flush();
            }
        } else {// File resource path does not exist
            bw.write(" File not found ");
            bw.newLine();
            bw.flush();
        }

        // Close all resources
        bw.close();
        osw.close();
        os.close();
        if (null != br2) {
            br2.close();
        }
        if (null != isr2) {
            isr2.close();
        }
        if (null != fis) {
            fis.close();
        }
        br.close();
        isr.close();
        is.close();
        ss.close();

    }

 System.out.println("================= client ===================");

        Scanner sc = new Scanner(System.in);
        // Open client
        Socket sk = new Socket("127.0.0.1", 7979);
        System.out.println("OK");
        System.out.println(" Please enter the resource path to download : ");
        String filePath = sc.next();

        // Write the resource path into the network
        OutputStream os = sk.getOutputStream();
        OutputStreamWriter osw = new OutputStreamWriter(os);
        BufferedWriter bw = new BufferedWriter(osw);

        bw.write(filePath);
        bw.newLine();
        bw.flush();

        // Receive the content sent by the server
        InputStream inputStream = sk.getInputStream();
        InputStreamReader isr = new InputStreamReader(inputStream);
        BufferedReader br = new BufferedReader(isr);

        // Get the name of the file
        String fileName = filePath.substring(filePath.lastIndexOf("/"));

        // After reading the content Write to local through file
        FileOutputStream fos = new FileOutputStream("D:\\zking\\" + fileName);
        BufferedWriter bw2 = new BufferedWriter(new OutputStreamWriter(fos));

        String str = br.readLine();
        if (" File not found ".equals(str)) {
            System.out.println(" Resource does not exist ");
        } else {
            System.out.println(str);
            bw2.write(str);
            bw2.newLine();
            bw2.flush();
            while (null != (str = br.readLine())) {
                // System.out.println(str);
                bw2.write(str);
                bw2.newLine();
                bw2.flush();

                // write(byte[],0,len)
            }