最近需要進行網絡傳輸大文件，于是對基于socket的文件傳輸作了一個初步的了解。在一位網友提供的程序基礎上，俺進行了一些加工，采用了緩沖輸入/輸出流來包裝輸出流，再采用數據輸入/輸出輸出流進行包裝，加快傳輸的速度。廢話少說，先來看服務器端的程序。

1.服務器端

package sterning;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerTest {
int port = 8821 ;

void start() {
Sockets = null ;
try {
ServerSocketss = new ServerSocket(port);
while ( true ) {
// 選擇進行傳輸的文件
StringfilePath = " D://lib.rar " ;
Filefi = new File(filePath);

System.out.println( " 文件長度: " + ( int )fi.length());

// publicSocketaccept()throws
// IOException偵聽并接受到此套接字的連接。此方法在進行連接之前一直阻塞。

s = ss.accept();
System.out.println( " 建立socket鏈接 " );
DataInputStreamdis = new DataInputStream( new BufferedInputStream(s.getInputStream()));
dis.readByte();

DataInputStreamfis = new DataInputStream( new BufferedInputStream( new FileInputStream(filePath)));
DataOutputStreamps = new DataOutputStream(s.getOutputStream());
// 將文件名及長度傳給客戶端。這里要真正適用所有平臺，例如中文名的處理，還需要加工，具體可以參見ThinkInJava4th里有現成的代碼。
ps.writeUTF(fi.getName());
ps.flush();
ps.writeLong(( long )fi.length());
ps.flush();

int bufferSize = 8192 ;
byte []buf = new byte [bufferSize];

while ( true ) {
int read = 0 ;
if (fis != null ) {
read = fis.read(buf);
}

if (read == - 1 ) {
break ;
}
ps.write(buf, 0 ,read);
}
ps.flush();
// 注意關閉socket鏈接哦，不然客戶端會等待server的數據過來，
// 直到socket超時，導致數據不完整。
fis.close();
s.close();
System.out.println( " 文件傳輸完成 " );
}

} catch (Exceptione) {
e.printStackTrace();
}
}

public static void main(Stringarg[]) {
new ServerTest().start();
}
}

2.socket的Util輔助類

package sterning;

import java.net. * ;
import java.io. * ;

public class ClientSocket {
private Stringip;

private int port;

private Socketsocket = null ;

DataOutputStreamout = null ;

DataInputStreamgetMessageStream = null ;

public ClientSocket(Stringip, int port) {
this .ip = ip;
this .port = port;
}

/**
*創建socket連接
*
* @throws Exception
*exception
*/
public void CreateConnection() throws Exception {
try {
socket = new Socket(ip,port);
} catch (Exceptione) {
e.printStackTrace();
if (socket != null )
socket.close();
throw e;
} finally {
}
}

public void sendMessage(StringsendMessage) throws Exception {
try {
out = new DataOutputStream(socket.getOutputStream());
if (sendMessage.equals( " Windows " )) {
out.writeByte( 0x1 );
out.flush();
return ;
}
if (sendMessage.equals( " Unix " )) {
out.writeByte( 0x2 );
out.flush();
return ;
}
if (sendMessage.equals( " Linux " )) {
out.writeByte( 0x3 );
out.flush();
} else {
out.writeUTF(sendMessage);
out.flush();
}
} catch (Exceptione) {
e.printStackTrace();
if (out != null )
out.close();
throw e;
} finally {
}
}

public DataInputStreamgetMessageStream() throws Exception {
try {
getMessageStream = new DataInputStream( new BufferedInputStream(socket.getInputStream()));
return getMessageStream;
} catch (Exceptione) {
e.printStackTrace();
if (getMessageStream != null )
getMessageStream.close();
throw e;
} finally {
}
}

public void shutDownConnection() {
try {
if (out != null )
out.close();
if (getMessageStream != null )
getMessageStream.close();
if (socket != null )
socket.close();
} catch (Exceptione) {

}
}
}

3.客戶端

package sterning;

import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileOutputStream;

public class ClientTest {
private ClientSocketcs = null ;

private Stringip = " localhost " ; // 設置成服務器IP

private int port = 8821 ;

private StringsendMessage = " Windwos " ;

public ClientTest() {
try {
if (createConnection()) {
sendMessage();
getMessage();
}

} catch (Exceptionex) {
ex.printStackTrace();
}
}

private boolean createConnection() {
cs = new ClientSocket(ip,port);
try {
cs.CreateConnection();
System.out.print( " 連接服務器成功! " + " /n " );
return true ;
} catch (Exceptione) {
System.out.print( " 連接服務器失敗! " + " /n " );
return false ;
}

}

private void sendMessage() {
if (cs == null )
return ;
try {
cs.sendMessage(sendMessage);
} catch (Exceptione) {
System.out.print( " 發送消息失敗! " + " /n " );
}
}

private void getMessage() {
if (cs == null )
return ;
DataInputStreaminputStream = null ;
try {
inputStream = cs.getMessageStream();
} catch (Exceptione) {
System.out.print( " 接收消息緩存錯誤/n " );
return ;
}

try {
// 本地保存路徑，文件名會自動從服務器端繼承而來。
StringsavePath = " E:// " ;
int bufferSize = 8192 ;
byte []buf = new byte [bufferSize];
int passedlen = 0 ;
long len = 0 ;

savePath += inputStream.readUTF();
DataOutputStreamfileOut = new DataOutputStream( new BufferedOutputStream( new BufferedOutputStream( new FileOutputStream(savePath))));
len = inputStream.readLong();

System.out.println( " 文件的長度為: " + len + " /n " );
System.out.println( " 開始接收文件! " + " /n " );

while ( true ) {
int read = 0 ;
if (inputStream != null ) {
read = inputStream.read(buf);
}
passedlen += read;
if (read == - 1 ) {
break ;
}
// 下面進度條本為圖形界面的prograssBar做的，這里如果是打文件，可能會重復打印出一些相同的百分比
System.out.println( " 文件接收了 " + (passedlen * 100 / len) + " %/n " );
fileOut.write(buf, 0 ,read);
}
System.out.println( " 接收完成，文件存為 " + savePath + " /n " );

fileOut.close();
} catch (Exceptione) {
System.out.println( " 接收消息錯誤 " + " /n " );
return ;
}
}

public static void main(Stringarg[]) {
new ClientTest();
}
}

這就實現了從服務器端向客戶端發送文件的過程,當然,反過來,也一樣.稍有不同.代碼中對跨平臺的細節沒有實現,有時間或興趣的朋友可以提供一下.

Java基于Socket文件傳輸示例