HttpConnection方式访问网络

2023-07-24 08:25:58

参考疯狂android讲义，重点在于学习1、HttpConnection访问网络2、多线程下载文件的处理

主activity：

package com.example.multithreaddownload;

import java.util.Timer;

import java.util.TimerTask;

//import org.crazyit.net.R;

import android.annotation.SuppressLint;

import android.app.Activity;

import android.os.Bundle;

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;

@SuppressLint("HandlerLeak")

public class MultiThreadDown extends Activity {

    EditText target;

    EditText url;

    Button downButton;

    ProgressBar bar;

    DownUtil downUtil;

    private int mDownloadStatus;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        url = (EditText) findViewById(R.id.url);

        target = (EditText) findViewById(R.id.target);

        downButton = (Button) findViewById(R.id.down);

        bar = (ProgressBar) findViewById(R.id.bar);

        final Handler handler = new Handler(){

            public void handleMessage(Message msg)

            {

                if(msg.what == 0x123)

                {

                    bar.setProgress(mDownloadStatus);

                }

            }

        };

        downButton.setOnClickListener(new OnClickListener()

        {

            @Override

            public void onClick(View v) {

                // 

                downUtil = new DownUtil(url.getText().toString(),

                        target.getText().toString(),5);

                try{

                    downUtil.download();

                }catch(Exception e)

                {

                    e.printStackTrace();

                }

                //设置定时器

                final Timer timer = new Timer();

                timer.schedule(new TimerTask()

                {

                    @Override

                    public void run() {

                        //

                        double completeRate = downUtil.getCompleteRate();

                        mDownloadStatus = (int) (completeRate * 100);

                        handler.sendEmptyMessage(0x123);

                        if(mDownloadStatus >= 100)

                        {

                            timer.cancel();

                        }

                    }

                }, 0, 100);

            }

        });

    }

}

package com.example.multithreaddownload;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.net.HttpURLConnection;

import java.net.URL;

public class DownUtil {

    private String path;

    private String targetFile;

    private int threadNum;

    private DownloadThread[] threads;

    private int fileSize;

    public DownUtil(String path, String targetFile, int threadNum) {

        super();

        this.path = path;

        this.targetFile = targetFile;

        //初始化thread数组

        threads = new DownloadThread[threadNum];

        this.threadNum = threadNum;

    }

    public void download() throws Exception

    {

        URL url = new URL(path);

        HttpURLConnection connection = (HttpURLConnection) url.openConnection();//开启http链接

        connection.setRequestMethod("GET");//向服务器发送GET请求获取数据

        connection.setConnectTimeout(5000);//设置连接超时为5s

//        connection.setRequestProperty(

//                "Accept",

//                "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");

//        connection.setRequestProperty("Accept-Language", "zh-CN");

//        connection.setRequestProperty("Charset", "UTF-8");

//        connection.setRequestProperty(

//                "User-Agent",

//                "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");

//        connection.setRequestProperty("Connection", "Keep-Alive");

        fileSize = connection.getContentLength();//获取文件大小

        connection.disconnect();//关闭http连接

        int currentPartSize = fileSize / threadNum +1;//按线程数分割后文件块的大小

        RandomAccessFile file = new RandomAccessFile(targetFile, "rw");//随机产生本地目标文件

        file.setLength(fileSize);//根据fileSize设置本地文件大小

        file.close();//关闭文件

        for(int i = 0; i < threadNum; i++)

        {

            //计算每条线程下载的开始位置

            int startPos = i * currentPartSize;

            //每个线程使用一个RandomAccessFile进行下载

            RandomAccessFile currentPart = new RandomAccessFile(targetFile, "rw");

            //定位该线程的下载位置

            currentPart.seek(startPos);

            //创建下载线程

            threads[i] = new DownloadThread(startPos, currentPartSize,

                    currentPart);

            threads[i].start();

        }

    }

    // 获取下载的完成百分比

    public double getCompleteRate()

    {

        // 统计多条线程已经下载的总大小

        int sumSize = 0;

        for (int i = 0; i < threadNum; i++)

        {

            sumSize += threads[i].length;

        }

        // 返回已经完成的百分比

        return sumSize * 1.0 / fileSize;

    }

    private class DownloadThread extends Thread{

        //当前线程下载的位置

        private int startPos;

        //定义当前线程负责下载的文件大小

        private int currentPartSize;

        //定义当前线程负责的下载块

        private RandomAccessFile currentPart;

        //定义该线程已下载的字节数

        public int length;

        public DownloadThread(int startPos, int currentPartSize,

                RandomAccessFile currentPart) {

//            super();

            this.startPos = startPos;

            this.currentPartSize = currentPartSize;

            this.currentPart = currentPart;

        }

        @Override

        public void run() {

            super.run();

            try{

                URL url = new URL(path);

                HttpURLConnection connection = (HttpURLConnection) url.openConnection();

                connection.setRequestMethod("GET");

                connection.setConnectTimeout(5000);

//                connection.setReadTimeout(5000);

//                connection.setRequestProperty(

//                        "Accept",

//                        "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");

//                connection.setRequestProperty("Accept-Language", "zh-CN");

//                connection.setRequestProperty("Charset", "UTF-8");

                InputStream in = connection.getInputStream();

                //跳过startPos个字节，只下载本线程负责的文件块

                in.skip(this.startPos);

                byte[] buffer = new byte[1024];

                int hasRead = 0;

                while((length < currentPartSize) && (hasRead = in.read(buffer)) != -1)

                {

                    currentPart.write(buffer, 0, hasRead);

                    length += hasRead;

                }

                currentPart.close();

                in.close();            

            }catch(Exception e)

            {

                e.printStackTrace();

            }

        }

    }

}

activity_main.xml文件：

<?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="要下载的资源的URL："

    />

<EditText

    android:id="@+id/url"

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:text="http://www.crazyit.org/attachment.php?aid=1093&amp;k=4ec76aeaa41ee84acf667b420e926783&amp;t=1297311085"

    />

<TextView

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:text="目标文件："

    />

<EditText

    android:id="@+id/target"

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:text="/mnt/sdcard/a.rar"

    />

<Button

    android:id="@+id/down"

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:text="@string/down"

    />

<!-- 定义一个水平进度条,用于显示下载进度 -->

<ProgressBar

    android:id="@+id/bar"

     android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:max="100"

    style="@android:style/Widget.ProgressBar.Horizontal"

    />

</LinearLayout>

strings.xml:

<?xml version="1.0" encoding="utf-8"?>

<resources>

<string name="down">下载</string>

<string name="app_name">多线程下载</string>

<string name="action_settings">Settings</string>

</resources>

AndroidManifest.xml配置文件添加以下权限：

<!-- 在SD卡中创建与删除文件权限 -->

    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

    <!-- 向SD卡写入数据权限 -->

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

    <!-- 授权访问网络 -->

    <uses-permission android:name="android.permission.INTERNET"/>

运行结果：

码农公寓

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