主要功能是：
1、TCP服务器提供文件下载服务，服务器支持多线程。
2、TCP Client从服务器上下载指定的文件，Client也支持多线程。
首先是服务器，服务器是在PC机上，JAVA运行环境，主要参考网上的代码，自己做了支持多线程处理，代码如下：
复制代码 代码如下:
//file:DownloadServer.java
import java.net.*;
import java.io.*;
class ServerOneDownload extends Thread {
private Socket socket = null;
private String downloadRoot = null;
private static final int Buffer = 8 * 1024;
public ServerOneDownload(Socket socket, String downloadRoot) {
super();
this.socket = socket;
this.downloadRoot = downloadRoot;
start();
}
// 检查文件是否真实存在，核对下载密码，若文件不存在或密码错误，则返回-1，否则返回文件长度
// 此处只要密码不为空就认为是正确的
private long getFileLength(String fileName, String password) {
// 若文件名或密码为null，则返回-1
if ((fileName == null) || (password == null))
return -1;
// 若文件名或密码长度为0，则返回-1
if ((fileName.length() == 0) || (password.length() == 0))
return -1;
String filePath = downloadRoot + fileName; // 生成完整文件路径
System.out.println("DownloadServer getFileLength----->" + filePath);
File file = new File(filePath);
// 若文件不存在，则返回-1
if (!file.exists())
return -1;
return file.length(); // 返回文件长度
}
// 用指定输出流发送指定文件
private void sendFile(DataOutputStream out, String fileName)
throws Exception {
String filePath = downloadRoot + fileName; // 生成完整文件路径
// 创建与该文件关联的文件输入流
FileInputStream in = new FileInputStream(filePath);
System.out.println("DownloadServer sendFile----->" + filePath);
byte[] buf = new byte[Buffer];
int len;
// 反复读取该文件中的内容，直到读到的长度为-1
while ((len = in.read(buf)) >= 0) {
out.write(buf, 0, len); // 将读到的数据，按读到的长度写入输出流
out.flush();
}
out.close();
in.close();
}
// 提供下载服务
public void download() throws IOException {
System.out.println("启动下载... ");
System.out.println("DownloadServer currentThread--->"
+ currentThread().getName());
System.out.println("DownloadServer currentThread--->"
+ currentThread().getId());
// 获取socket的输入流并包装成BufferedReader
BufferedReader in = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
// 获取socket的输出流并包装成DataOutputStream
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
try {
String parameterString = in.readLine(); // 接收下载请求参数
// 下载请求参数字符串为自定义的格式，由下载文件相对于下载根目录的路径和
// 下载密码组成，两者间以字符 "@ "分隔，此处按 "@ "分割下载请求参数字符串
String[] parameter = parameterString.split("@ ");
String fileName = parameter[0]; // 获取相对文件路径
String password = parameter[1]; // 获取下载密码
// 打印请求下载相关信息
System.out.print(socket.getInetAddress().getHostAddress()
+ "提出下载请求， ");
System.out.println("请求下载文件: " + fileName);
// 检查文件是否真实存在，核对下载密码，获取文件长度
long len = getFileLength(fileName, password);
System.out.println("download fileName----->" + fileName);
System.out.println("download password----->" + password);
out.writeLong(len); // 向客户端返回文件大小
out.flush();
// 若获取的文件长度大于等于0,则允许下载，否则拒绝下载
if (len >= 0) {
System.out.println("允许下载 ");
System.out.println("正在下载文件 " + fileName + "... ");
sendFile(out, fileName); // 向客户端发送文件
System.out.println(fileName +": "+"下载完毕 ");
} else {
System.out.println("下载文件不存在或密码错误，拒绝下载！ ");
}
} catch (Exception e) {
System.out.println(e.toString());
} finally {
socket.close(); // 关闭socket
}
}
@Override
public void run() {
try {
download();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// TODO Auto-generated method stub
super.run();
}
}
public class DownloadServer {
private final static int port = 65525;
private static String root = "C:// "; // 下载根目录
public static void main(String[] args) throws IOException {
String temp = null;
// 监听端口
try {
// 包装标准输入为BufferedReader
BufferedReader systemIn = new BufferedReader(new InputStreamReader(
System.in));
while (true) {
System.out.print("请输入下载服务器的下载根目录： ");
root = systemIn.readLine().trim(); // 从标准输入读取下载根目录
File file = new File(root);
// 若该目录确实存在且为目录，则跳出循环
if ((file.exists()) && (file.isDirectory())) {
temp = root.substring(root.length() - 1, root.length());
if (!temp.equals("//"))
root += "//";
}
break;
}
} catch (Exception e) {
System.out.println(e.toString());
}
ServerSocket serverSocket = new ServerSocket(port);
System.out.println("Server start...");
try {
while (true) {
Socket socket = serverSocket.accept();
new ServerOneDownload(socket, root);
}
} finally {
serverSocket.close();
}
}
}
File Download Client
Client输入IP和文件名即可直接从服务器上下载，还是看代码。
复制代码 代码如下:
//file:DownLoadClient.java
package org.piaozhiye.study;
import java.io.IOException;
import java.net.Socket;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class DownLoadClient extends Activity {
private Button download = null;
private EditText et_serverIP = null;
private EditText et_fileName= null;
private String downloadFile = null;
private final static int PORT = 65525;
private final static String defaultIP = "192.168.0.100";
private static String serverIP = null;
private Socket socket;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
download = (Button)findViewById(R.id.download);
et_serverIP= (EditText)findViewById(R.id.et_serverip);
et_fileName = (EditText)findViewById(R.id.et_filename);
et_serverIP.setText("192.168.0.100");
download.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
serverIP = et_serverIP.getText().toString();
if(serverIP == null){
serverIP = defaultIP;
}
System.out.println("DownLoadClient serverIP--->" + serverIP );
System.out.println("DownLoadClient MainThread--->" + Thread.currentThread().getId() );
try{
socket = new Socket(serverIP, PORT);
}catch(IOException e){
}
downloadFile = et_fileName.getText().toString();
Thread downFileThread = new Thread(new DownFileThread(socket, downloadFile));
downFileThread.start();
System.out.println("DownLoadClient downloadFile--->" + downloadFile );
}
});
}
}
file:DownFileThread.java
复制代码 代码如下:
package org.piaozhiye.study;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
public class DownFileThread extends Thread {
private Socket socket;
private String downloadFile;
private final static int Buffer = 8 * 1024;
public DownFileThread(Socket socket, String downloadFile) {
super();
this.socket = socket;
this.downloadFile = downloadFile;
}
public Socket getSocket() {
return socket;
}
public void setSocket(Socket socket) {
this.socket = socket;
}
public String getDownloadFile() {
return downloadFile;
}
public void setDownloadFile(String downloadFile) {
this.downloadFile = downloadFile;
}
// 向服务器提出下载请求，返回下载文件的大小
private long request(String fileName, String password) throws IOException {
// 获取socket的输入流并包装成DataInputStream
DataInputStream in = new DataInputStream(socket.getInputStream());
// 获取socket的输出流并包装成PrintWriter
PrintWriter out = new PrintWriter(new OutputStreamWriter(
socket.getOutputStream()));
// 生成下载请求字符串
String requestString = fileName + "@ " + password;
out.println(requestString); // 发出下载请求
out.flush();
return in.readLong(); // 接收并返回下载文件长度
}
// 接收并保存文件
private void receiveFile(String localFile) throws Exception {
// 获取socket的输入流并包装成BufferedInputStream
BufferedInputStream in = new BufferedInputStream(
socket.getInputStream());
// 获取与指定本地文件关联的文件输出流
FileOutputStream out = new FileOutputStream(localFile);
byte[] buf = new byte[Buffer];
int len;
// 反复读取该文件中的内容，直到读到的长度为-1
while ((len = in.read(buf)) >= 0) {
out.write(buf, 0, len); // 将读到的数据，按读到的长度写入输出流
out.flush();
}
out.close();
in.close();
}
// 从服务器下载文件
public void download(String downloadFile) throws Exception {
try {
String password = "password";
// String downloadFile ="imissyou.mp3";
String localpath = "/sdcard/";
String localFile = localpath + downloadFile;
long fileLength = request(downloadFile, password);
// 若获取的文件长度大于等于0，说明允许下载，否则说明拒绝下载
if (fileLength >= 0) {
System.out.println("fileLength: " + fileLength + " B");
System.out.println("downing...");
receiveFile(localFile); // 从服务器接收文件并保存至本地文件
System.out.println("file:" + downloadFile + " had save to "
+ localFile);
} else {
System.out.println("download " + downloadFile + " error! ");
}
} catch (IOException e) {
System.out.println(e.toString());
} finally {
socket.close(); // 关闭socket
}
}
@Override
public void run() {
System.out.println("DownFileThread currentThread--->"
+ DownFileThread.currentThread().getId());
// TODO Auto-generated method stub
try {
download(downloadFile);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
super.run();
}
}
layout.xml
复制代码 代码如下:
<?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="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
android:text="服务器IP:"
/>
<EditText
android:id="@+id/et_serverip"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
android:text="下载文件名:"
/>
<EditText
android:id="@+id/et_filename"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
/>
<Button
android:id="@+id/download"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="download"
/>
</LinearLayout>
同时别忘了权限：
<uses-permission android:name="android.permission.INTERNET" />