Android TCP 文件客户端与服务器DEMO介绍

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：

//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。

//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

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

<?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" />