什么是Socket?
所谓Socket通常也称作“套接字”，用于描述IP地址和端口，是一个通信连的句柄，应用程序通常通过“套接字”向网络发送请求或者应答网络请求，它就是网络通信过程中端点的抽象表示。它主要包括以下两个协议：
TCP (Transmission Control Protocol 传输控制协议)：传输控制协议,提供的是面向连接、可靠的字节流服务。当客户和服务器彼此交换数据前，必须先在双方之间建立一个TCP连接，之后才能传输数据。TCP提供超时重发，丢弃重复数据，检验数据，流量控制等功能，保证数据能从一端传到另一端。
UDP (User Datagram Protocl 用户数据报协议)：用户数据报协议，是一个简单的面向数据报的运输层协议。UDP不提供可靠性，它只是把应用程序传给IP层的数据报发送出去，但是并不能保证它们能到达目的地。由于UDP在传输数据报前不用在客户和服务器之间建立一个连接，且没有超时重发等机制，故而传输速度很快。
详细解说如下:
TCP传输和UDP不一样，TCP传输是流式的，必须先建立连接，然后数据流沿已连接的线路(虚电路)传输。因此TCP的数据流不会像UDP数据报一样，每个数据报都要包含目标地址和端口，因为每个数据报要单独路由。TCP传输则只需要在建立连接时指定目标地址和端口就可以了。
形象的讲，TCP就像打电话，UDP就像发电报。宏观上来看UDP是不分客户端和服务端的。通信双方是平等的。微观上来讲只相对一个报文，发送端是客户端，监听端是服务端。发送端把数据报发给路由器就像把电报发给了邮局，后面的事情就是发送者无法控制，也无从知晓的了。所以说是不可靠的，可能会出现报文丢失而无从知晓。就像每张电报都要有收件人一样，每个数据报都要有目的地址和端口。
而TCP每次连接都是分客户端和服务端的。连接的发起者(相当与拨号打电话的人)是客户端，监听者(相当于在电话边等着接电话的人)是服务端。发起者指定要连接的服务器地址和端口(相当于拨号)，监听者通过和发起者三次握手建立连接(相当于听到电话响去接电话)。建立连接后双方可以互相发送和接受数据(打电话)。
Java如何操作Socket?
值得一提的是，Java分别为TCP和UDP提供了相应的类,TCP是java.net中提供了两个类Socket和ServerSocket，分别用来表示双向连接的客户端和服务端。这是两个封装得非常好的类，使用起来很方便！UDP是java.net.DatagramSocket.
127.0.0.1是回路地址,用于测试,相当于localhost本机地址,没有网卡,不设DNS都可以访问,端口地址在0~65535之间,其中0~1023之间的端口是用于一些知名的网络服务和应用,用户的普通网络应用程序应该使用1024以上的端口.
Socket通信模型如下：
如果大家对Java Socket编程还有模糊的地方抓紧温习(http://blog.csdn.net/shimiso/article/details/8529941),本文不在此赘述,下面我们以最常用的TCP协议举例:
服务器，使用ServerSocket监听指定的端口，端口可以随意指定（由于1024以下的端口通常属于保留端口，在一些操作系统中不可以随意使用，所以建议使用大于1024的端口），等待客户连接请求，客户连接后，会话产生；在完成会话后，关闭连接。
客户端，使用Java socket通信对网络上某一个服务器的某一个端口发出连接请求，一旦连接成功，打开会话；会话完成后，关闭Socket。客户端不需要指定打开的端口，通常临时的、动态的分配一个1024以上的端口。
TCP网络连接模型：
Android客户端程序代分析:
UploadActivity.java
package com.android.upload;
import java.io.File;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.io.RandomAccessFile;
import java.net.Socket;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.android.service.UploadLogService;
import com.android.socket.utils.StreamTool;
public class UploadActivity extends Activity {
private EditText filenameText;
private TextView resulView;
private ProgressBar uploadbar;
private UploadLogService logService;
private boolean start=true;
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
int length = msg.getData().getInt("size");
uploadbar.setProgress(length);
float num = (float)uploadbar.getProgress()/(float)uploadbar.getMax();
int result = (int)(num * 100);
resulView.setText(result+ "%");
if(uploadbar.getProgress()==uploadbar.getMax()){
Toast.makeText(UploadActivity.this, R.string.success, 1).show();
}
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
logService = new UploadLogService(this);
filenameText = (EditText)this.findViewById(R.id.filename);
uploadbar = (ProgressBar) this.findViewById(R.id.uploadbar);
resulView = (TextView)this.findViewById(R.id.result);
Button button =(Button)this.findViewById(R.id.button);
Button button1 =(Button)this.findViewById(R.id.stop);
button1 .setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
start=false;
}
});
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
start=true;
String filename = filenameText.getText().toString();
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
File uploadFile = new File(Environment.getExternalStorageDirectory(), filename);
if(uploadFile.exists()){
uploadFile(uploadFile);
}else{
Toast.makeText(UploadActivity.this, R.string.filenotexsit, 1).show();
}
}else{
Toast.makeText(UploadActivity.this, R.string.sdcarderror, 1).show();
}
}
});
}
/**
* 上传文件
* @param uploadFile
*/
private void uploadFile(final File uploadFile) {
new Thread(new Runnable() {
@Override
public void run() {
try {
uploadbar.setMax((int)uploadFile.length());
String souceid = logService.getBindId(uploadFile);
String head = "Content-Length="+ uploadFile.length() + ";filename="+ uploadFile.getName() + ";sourceid="+
(souceid==null? "" : souceid)+"\r\n";
Socket socket = new Socket("192.168.1.78",7878);
OutputStream outStream = socket.getOutputStream();
outStream.write(head.getBytes());
PushbackInputStream inStream = new PushbackInputStream(socket.getInputStream());
String response = StreamTool.readLine(inStream);
String[] items = response.split(";");
String responseid = items[0].substring(items[0].indexOf("=")+1);
String position = items[1].substring(items[1].indexOf("=")+1);
if(souceid==null){//代表原来没有上传过此文件，往数据库添加一条绑定记录
logService.save(responseid, uploadFile);
}
RandomAccessFile fileOutStream = new RandomAccessFile(uploadFile, "r");
fileOutStream.seek(Integer.valueOf(position));
byte[] buffer = new byte[1024];
int len = -1;
int length = Integer.valueOf(position);
while(start&&(len = fileOutStream.read(buffer)) != -1){
outStream.write(buffer, 0, len);
length += len;
Message msg = new Message();
msg.getData().putInt("size", length);
handler.sendMessage(msg);
}
fileOutStream.close();
outStream.close();
inStream.close();
socket.close();
if(length==uploadFile.length()) logService.delete(uploadFile);
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
}
StreamTool.java
package com.android.socket.utils;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
public class StreamTool {
public static void save(File file, byte[] data) throws Exception {
FileOutputStream outStream = new FileOutputStream(file);
outStream.write(data);
outStream.close();
}
public static String readLine(PushbackInputStream in) throws IOException {
char buf[] = new char[128];
int room = buf.length;
int offset = 0;
int c;
loop: while (true) {
switch (c = in.read()) {
case -1:
case '\n':
break loop;
case '\r':
int c2 = in.read();
if ((c2 != '\n') && (c2 != -1)) in.unread(c2);
break loop;
default:
if (--room < 0) {
char[] lineBuffer = buf;
buf = new char[offset + 128];
room = buf.length - offset - 1;
System.arraycopy(lineBuffer, 0, buf, 0, offset);
}
buf[offset++] = (char) c;
break;
}
}
if ((c == -1) && (offset == 0)) return null;
return String.copyValueOf(buf, 0, offset);
}
/**
* 读取流
* @param inStream
* @return 字节数组
* @throws Exception
*/
public static byte[] readStream(InputStream inStream) throws Exception{
ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = -1;
while( (len=inStream.read(buffer)) != -1){
outSteam.write(buffer, 0, len);
}
outSteam.close();
inStream.close();
return outSteam.toByteArray();
}
}
UploadLogService.java
package com.android.service;
import java.io.File;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
public class UploadLogService {
private DBOpenHelper dbOpenHelper;
public UploadLogService(Context context){
this.dbOpenHelper = new DBOpenHelper(context);
}
public void save(String sourceid, File uploadFile){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("insert into uploadlog(uploadfilepath, sourceid) values(?,?)",
new Object[]{uploadFile.getAbsolutePath(),sourceid});
}
public void delete(File uploadFile){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("delete from uploadlog where uploadfilepath=?", new Object[]{uploadFile.getAbsolutePath()});
}
public String getBindId(File uploadFile){
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select sourceid from uploadlog where uploadfilepath=?",
new String[]{uploadFile.getAbsolutePath()});
if(cursor.moveToFirst()){
return cursor.getString(0);
}
return null;
}
}
DBOpenHelper.java
package com.android.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
public DBOpenHelper(Context context) {
super(context, "upload.db", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE uploadlog (_id integer primary key autoincrement, uploadfilepath varchar(100), sourceid varchar(10))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS uploadlog");
onCreate(db);
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/filename"
/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="022.jpg"
android:id="@+id/filename"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button"
android:id="@+id/button"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="暂停"
android:id="@+id/stop"
/>
<ProgressBar
android:layout_width="fill_parent"
android:layout_height="20px"
style="?android:attr/progressBarStyleHorizontal"
android:id="@+id/uploadbar"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:id="@+id/result"
/>
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.upload"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".UploadActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<!-- 访问网络的权限 -->
<uses-permission android:name="android.permission.INTERNET"/>
<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>
Java服务端:
SocketServer.javapackage com.android.socket.server;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.io.RandomAccessFile;
import java.net.ServerSocket;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import com.android.socket.utils.StreamTool;
public class SocketServer {
private String uploadPath="D:/uploadFile/";
private ExecutorService executorService;// 线程池
private ServerSocket ss = null;
private int port;// 监听端口
private boolean quit;// 是否退出
private Map<Long, FileLog> datas = new HashMap<Long, FileLog>();// 存放断点数据，最好改为数据库存放
public SocketServer(int port) {
this.port = port;
// 初始化线程池
executorService = Executors.newFixedThreadPool(Runtime.getRuntime()
.availableProcessors() * 50);
}
// 启动服务
public void start() throws Exception {
ss = new ServerSocket(port);
while (!quit) {
Socket socket = ss.accept();// 接受客户端的请求
// 为支持多用户并发访问，采用线程池管理每一个用户的连接请求
executorService.execute(new SocketTask(socket));// 启动一个线程来处理请求
}
}
// 退出
public void quit() {
this.quit = true;
try {
ss.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
SocketServer server = new SocketServer(7878);
server.start();
}
private class SocketTask implements Runnable {
private Socket socket;
public SocketTask(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
System.out.println("accepted connenction from "
+ socket.getInetAddress() + " @ " + socket.getPort());
PushbackInputStream inStream = new PushbackInputStream(
socket.getInputStream());
// 得到客户端发来的第一行协议数据：Content-Length=143253434;filename=xxx.3gp;sourceid=
// 如果用户初次上传文件，sourceid的值为空。
String head = StreamTool.readLine(inStream);
System.out.println(head);
if (head != null) {
// 下面从协议数据中读取各种参数值
String[] items = head.split(";");
String filelength = items[0].substring(items[0].indexOf("=") + 1);
String filename = items[1].substring(items[1].indexOf("=") + 1);
String sourceid = items[2].substring(items[2].indexOf("=") + 1);
Long id = System.currentTimeMillis();
FileLog log = null;
if (null != sourceid && !"".equals(sourceid)) {
id = Long.valueOf(sourceid);
log = find(id);//查找上传的文件是否存在上传记录
}
File file = null;
int position = 0;
if(log==null){//如果上传的文件不存在上传记录,为文件添加跟踪记录
String path = new SimpleDateFormat("yyyy/MM/dd/HH/mm").format(new Date());
File dir = new File(uploadPath+ path);
if(!dir.exists()) dir.mkdirs();
file = new File(dir, filename);
if(file.exists()){//如果上传的文件发生重名，然后进行改名
filename = filename.substring(0, filename.indexOf(".")-1)+ dir.listFiles().length+ filename.substring(filename.indexOf("."));
file = new File(dir, filename);
}
save(id, file);
}else{// 如果上传的文件存在上传记录,读取上次的断点位置
file = new File(log.getPath());//从上传记录中得到文件的路径
if(file.exists()){
File logFile = new File(file.getParentFile(), file.getName()+".log");
if(logFile.exists()){
Properties properties = new Properties();
properties.load(new FileInputStream(logFile));
position = Integer.valueOf(properties.getProperty("length"));//读取断点位置
}
}
}
OutputStream outStream = socket.getOutputStream();
String response = "sourceid="+ id+ ";position="+ position+ "\r\n";
//服务器收到客户端的请求信息后，给客户端返回响应信息：sourceid=1274773833264;position=0
//sourceid由服务生成，唯一标识上传的文件，position指示客户端从文件的什么位置开始上传
outStream.write(response.getBytes());
RandomAccessFile fileOutStream = new RandomAccessFile(file, "rwd");
if(position==0) fileOutStream.setLength(Integer.valueOf(filelength));//设置文件长度
fileOutStream.seek(position);//移动文件指定的位置开始写入数据
byte[] buffer = new byte[1024];
int len = -1;
int length = position;
while( (len=inStream.read(buffer)) != -1){//从输入流中读取数据写入到文件中
fileOutStream.write(buffer, 0, len);
length += len;
Properties properties = new Properties();
properties.put("length", String.valueOf(length));
FileOutputStream logFile = new FileOutputStream(new File(file.getParentFile(), file.getName()+".log"));
properties.store(logFile, null);//实时记录文件的最后保存位置
logFile.close();
}
if(length==fileOutStream.length()) delete(id);
fileOutStream.close();
inStream.close();
outStream.close();
file = null;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if(socket != null && !socket.isClosed()) socket.close();
} catch (IOException e) {}
}
}
}
public FileLog find(Long sourceid) {
return datas.get(sourceid);
}
// 保存上传记录
public void save(Long id, File saveFile) {
// 日后可以改成通过数据库存放
datas.put(id, new FileLog(id, saveFile.getAbsolutePath()));
}
// 当文件上传完毕，删除记录
public void delete(long sourceid) {
if (datas.containsKey(sourceid))
datas.remove(sourceid);
}
private class FileLog {
private Long id;
private String path;
public FileLog(Long id, String path) {
super();
this.id = id;
this.path = path;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
}
}
ServerWindow.javapackage com.android.socket.server;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
public class ServerWindow extends Frame{
private SocketServer server;
private Label label;
public ServerWindow(String title){
super(title);
server = new SocketServer(7878);
label = new Label();
add(label, BorderLayout.PAGE_START);
label.setText("服务器已经启动");
this.addWindowListener(new WindowListener() {
@Override
public void windowOpened(WindowEvent e) {
new Thread(new Runnable() {
@Override
public void run() {
try {
server.start();
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
@Override
public void windowIconified(WindowEvent e) {
}
@Override
public void windowDeiconified(WindowEvent e) {
}
@Override
public void windowDeactivated(WindowEvent e) {
}
@Override
public void windowClosing(WindowEvent e) {
server.quit();
System.exit(0);
}
@Override
public void windowClosed(WindowEvent e) {
}
@Override
public void windowActivated(WindowEvent e) {
}
});
}
/**
* @param args
*/
public static void main(String[] args) {
ServerWindow window = new ServerWindow("文件上传服务端");
window.setSize(300, 300);
window.setVisible(true);
}
}
StreamTool.javapackage com.android.socket.utils;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
public class StreamTool {
public static void save(File file, byte[] data) throws Exception {
FileOutputStream outStream = new FileOutputStream(file);
outStream.write(data);
outStream.close();
}
public static String readLine(PushbackInputStream in) throws IOException {
char buf[] = new char[128];
int room = buf.length;
int offset = 0;
int c;
loop: while (true) {
switch (c = in.read()) {
case -1:
case '\n':
break loop;
case '\r':
int c2 = in.read();
if ((c2 != '\n') && (c2 != -1)) in.unread(c2);
break loop;
default:
if (--room < 0) {
char[] lineBuffer = buf;
buf = new char[offset + 128];
room = buf.length - offset - 1;
System.arraycopy(lineBuffer, 0, buf, 0, offset);
}
buf[offset++] = (char) c;
break;
}
}
if ((c == -1) && (offset == 0)) return null;
return String.copyValueOf(buf, 0, offset);
}
/**
* 读取流
* @param inStream
* @return 字节数组
* @throws Exception
*/
public static byte[] readStream(InputStream inStream) throws Exception{
ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = -1;
while( (len=inStream.read(buffer)) != -1){
outSteam.write(buffer, 0, len);
}
outSteam.close();
inStream.close();
return outSteam.toByteArray();
}
}
运行效果如下:
Android前端控制:
后台监控日志:
下载后的文件路径:
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