Android版多线程下载器核心代码分享

首先给大家分享多线程下载核心类：

按 Ctrl+C 复制代码

按 Ctrl+C 复制代码

下面是界面的逻辑代码：

package com.example.urltest;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
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 java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

public class MultiThreadDown extends Activity {
    EditText url, target;
    Button downButton;
    ProgressBar bar;
    ProgressDialog progressDialog;
    View downView;
    DownUtil downUtil;
    private int mDownStatus;
    private int threadNum = 6; // 默认的线程数
    android.os.Handler handler = new android.os.Handler() {

        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 0x123) {
                bar.setProgress(mDownStatus);
                if (mDownStatus >= 100) {
                    Toast.makeText(MultiThreadDown.this, "下载完成", Toast.LENGTH_SHORT).show();
                }
                // Log.i("csx", "" + mDownStatus);

            }
        }

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_down);
        url = (EditText) findViewById(R.id.url);

        downButton = (Button) findViewById(R.id.down);
        bar = (ProgressBar) findViewById(R.id.bar);
        progressDialog = new ProgressDialog(this);
        progressDialog.setTitle("尝试连接");
        progressDialog.setMessage("正在连接...");
        downButton.setOnClickListener(new DownButtonOnClickListener());

    }

    private class DownButtonOnClickListener implements OnClickListener {

        EditText targetFilePath, fileName;
        TextView fileSize;
        Thread connectionThread;

        public Thread instanceOfConnectionThread() {
            return new Thread() {

                @Override
                public void run() {
                    try {
                        downUtil.getFileInformation();

                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }

                }

            };
        }

        @Override
        public void onClick(View v) {

            String urlPath = url.getText().toString();
            if (urlPath == null || urlPath.equals("")) {
                return;
            }
            progressDialog.show();
            downUtil = new DownUtil(urlPath, threadNum);
            connectionThread = instanceOfConnectionThread();
            connectionThread.start();

            int connectionNum = 3;
            while (!downUtil.isGetFileInformation() && connectionNum > 0) {// 循环请求连接,如果3次之后还没有连接成功，就退出
                if (!connectionThread.isAlive()) {
                    connectionThread = null;
                    connectionThread = instanceOfConnectionThread();
                    connectionThread.start();
                    connectionNum--;
                }

            }

            progressDialog.cancel();
            if (!downUtil.isGetFileInformation()) {
                Toast.makeText(MultiThreadDown.this, "请求失败！", Toast.LENGTH_SHORT).show();
                return;
            }
            downView = getLayoutInflater().inflate(R.layout.layout_download_view, null);
            targetFilePath = (EditText) downView.findViewById(R.id.editText_target_path);
            fileName = (EditText) downView.findViewById(R.id.editText_file_name);
            fileSize = (TextView) downView.findViewById(R.id.textView_file_size);
            targetFilePath.setText(downUtil.getDefaultTargetPath());
            fileName.setText(downUtil.getFileName());
            fileSize.append("" + ((double) downUtil.getFileSize()) / 1024 + "k");

            new AlertDialog.Builder(MultiThreadDown.this).setView(downView)
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            if (!downUtil.isGetFileInformation()) {
                                dialog.dismiss();
                                return;
                            }
                            final String path = targetFilePath.getText().toString();
                            final String name = fileName.getText().toString();

                            new Thread() {

                                @Override
                                public void run() {
                                    try {
                                        downUtil.download(path, name);
                                    } catch (IOException e) {
                                        // TODO Auto-generated catch block
                                        e.printStackTrace();
                                    }

                                    final Timer timer = new Timer();
                                    TimerTask task = new TimerTask() {

                                        @Override
                                        public void run() {

                                            mDownStatus = (int) (downUtil.getCompleteRate() * 100);
                                            handler.sendEmptyMessage(0x123);
                                            if (mDownStatus >= 100) {
                                                timer.cancel();
                                            }

                                        }
                                    };
                                    timer.schedule(task, 0, 100);

                                }

                            }.start();

                        }
                    }).setNegativeButton("取消", null)
                    .setTitle(downUtil.isGetFileInformation() ? "链接可用" : "链接不可用").show();

        }
    }

}

下面是主页面布局：layout_down.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ScrollView
        android:id="@+id/scrollView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical" >

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="要下载的资源的URL：" />

            <EditText
                android:id="@+id/url"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="在在这里输入URL" />

            <Button
                android:id="@+id/down"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="下载" />
            <!-- 定义一个水平进度条,用于显示下载进度 -->

            <ProgressBar
                android:id="@+id/bar"
                style="?android:attr/progressBarStyleHorizontal"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:max="100" />
        </LinearLayout>
    </ScrollView>

</LinearLayout>

下面是下载选项dialog布局：layout_download_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="下载路径：" />

    <EditText
        android:id="@+id/editText_target_path"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="文件名：" />

    <EditText
        android:id="@+id/editText_file_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:maxLines="1"
        android:ems="10" />

    <TextView
        android:id="@+id/textView_file_size"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="文件大小：" />

</LinearLayout>

效果图如下：输入URL，点击下载弹出对话框，输入路径和文件名 点击确定开始下载