自定义下载的封装实现

DownloadHelper.java

package com.studio.asynctaskproject;import android.os.AsyncTask;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;/** * 1. download方法 url localPath listener * 2.listener:start success fail progress * 3.用asynctask封装的 * Created by Administrator on 2017/8/29. */class DownloadHelper {    static void download(String url, String localPath, OnDownloadListener listener) {        DownloadAsyncTask task = new DownloadAsyncTask(url, localPath, listener);        task.execute();    }    private static class DownloadAsyncTask extends AsyncTask<String, Integer, Boolean> {        String mUrl;        String mFilePath;        OnDownloadListener onDownloadListener;        DownloadAsyncTask(String mUrl, String mFilePath, OnDownloadListener onDownloadListener) {            this.mUrl = mUrl;            this.mFilePath = mFilePath;            this.onDownloadListener = onDownloadListener;        }        /**         * 在异步任务之前，在主线程中         */        @Override        protected void onPreExecute() {            super.onPreExecute();            //可操作UI  之前的准备工作            if (onDownloadListener != null) {                onDownloadListener.onStart();            }        }        /**         * 在另外一个线程中处理事件         *         * @param strings 入参         * @return 结果         */        @Override        protected Boolean doInBackground(String... strings) {            String apkUrl = mUrl;            try {                //构造URL                URL url = new URL(apkUrl);                //构造链接，并打开                URLConnection urlConnection = url.openConnection();                InputStream inputStream = urlConnection.getInputStream();                //获取了下载内容的总长度                int contentLength = urlConnection.getContentLength();                //对下载地址进行处理                File apkFile = new File(mFilePath);                if (apkFile.exists()) {                    boolean result = apkFile.delete();                    if (!result) {                        if (onDownloadListener != null) {                            onDownloadListener.onFail(-1, apkFile, "文件删除失败");                        }                        return false;                    }                }                //已下载的大小                int downloadSize = 0;                //byte数组                byte[] bytes = new byte[1024];                int length;                //创建一个输入管道                OutputStream outputStream = new FileOutputStream(mFilePath);                //不断的从网络读取字节到byte数组再写入文件中                while ((length = inputStream.read(bytes)) != -1) {                    //读取的字节放到文件管道里                    outputStream.write(bytes, 0, length);                    //累加下载进度                    downloadSize += length;                    //发送进度                    publishProgress(downloadSize * 100 / contentLength);                }                inputStream.close();                outputStream.close();            } catch (MalformedURLException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();                if (onDownloadListener != null) {                    onDownloadListener.onFail(-2, new File(mFilePath), e.getMessage());                }                return false;            }            if (onDownloadListener != null) {                onDownloadListener.onSuccess(0, new File(mFilePath));            }            return true;        }        @Override        protected void onPostExecute(Boolean aBoolean) {            super.onPostExecute(aBoolean);            //在UI线程中，执行结果 处理        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            //收到进度，然后处理：  在UI线程中            if (values != null && values.length > 0) {                if (onDownloadListener != null) {                    onDownloadListener.onProgress(values[0]);                }            }        }    }    public interface OnDownloadListener {        void onStart();        void onSuccess(int code, File file);        void onFail(int code, File file, String message);        void onProgress(int progress);        abstract class SimpleDownloadListener implements OnDownloadListener {            @Override            public void onStart() {            }            @Override            public void onProgress(int progress) {            }        }    }}

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MainActivity.java

package com.studio.asynctaskproject;import android.os.AsyncTask;import android.os.Bundle;import android.os.Environment;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.ProgressBar;import android.widget.TextView;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;/** * 1. 网络上请求数据：申请网络权限 读写存储权限 * 2. 布局我们的layout * 3. 下载前我们要做什么？  UI * 4. 下载中我们要做什么？  数据 * 5. 下载后我们要做什么？  UI */public class MainActivity extends AppCompatActivity {    public static final int INIT_PROGRESS = 0;    public static final String APK_URL = "http://download.sj.qq.com/upload/connAssitantDownload/upload/MobileAssistant_1.apk";    private ProgressBar mProgressBar;    private Button mDownloadButton;    private TextView mResultTextView;    private String FILE_NAME;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //初始化视图        initView();        //初始化UI数据        setData();        //设置点击监听        setListener();        DownloadHelper.download(APK_URL, "", new DownloadHelper.OnDownloadListener.SimpleDownloadListener() {            @Override            public void onSuccess(int code, File file) {            }            @Override            public void onFail(int code, File file, String message) {            }        });    }    /**     * 初始化视图     */    private void initView() {        mProgressBar = (ProgressBar) findViewById(R.id.progressBar);        mDownloadButton = (Button) findViewById(R.id.button);        mResultTextView = (TextView) findViewById(R.id.textView);    }    private void setListener() {        mDownloadButton.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                // TODO: 2017/8/20 下载任务                DownloadAsyncTask asyncTask = new DownloadAsyncTask();                asyncTask.execute(APK_URL);            }        });    }    private void setData() {        mProgressBar.setProgress(INIT_PROGRESS);        mDownloadButton.setText(R.string.click_download);        mResultTextView.setText(R.string.download_text);    }    /**     * String 入参     * Integer 进度     * Boolean 返回值     */    private class DownloadAsyncTask extends AsyncTask<String, Integer, Boolean> {        private String mFilePath;        /**         * 在异步任务之前，在主线程中         */        @Override        protected void onPreExecute() {            super.onPreExecute();            //可操作UI  之前的准备工作            mDownloadButton.setText(R.string.downloading);            mResultTextView.setText(R.string.downloading);            mProgressBar.setProgress(INIT_PROGRESS);        }        /**         * 在另外一个线程中处理事件         *         * @param strings 入参         * @return 结果         */        @Override        protected Boolean doInBackground(String... strings) {            if (strings != null && strings.length > 0) {                String apkUrl = strings[0];                try {                    //构造URL                    URL url = new URL(apkUrl);                    //构造链接，并打开                    URLConnection urlConnection = url.openConnection();                    InputStream inputStream = urlConnection.getInputStream();                    //获取了下载内容的总长度                    int contentLength = urlConnection.getContentLength();                    //下载地址准备，File.separator是斜线                    FILE_NAME = "imooc.apk";                    mFilePath = Environment.getExternalStorageDirectory()                            + File.separator + FILE_NAME;                    //对下载地址进行处理                    File apkFile = new File(mFilePath);                    if (apkFile.exists()) {                        boolean result = apkFile.delete();                        if (!result) {                            return false;                        }                    }                    //已下载的大小                    int downloadSize = 0;                    //byte数组                    byte[] bytes = new byte[1024];                    int length;                    //创建一个输入管道                    OutputStream outputStream = new FileOutputStream(mFilePath);                    //不断的从网络读取字节到byte数组再写入文件中                    while ((length = inputStream.read(bytes)) != -1) {                        //读取的字节放到文件管道里                        outputStream.write(bytes, 0, length);                        //累加下载进度                        downloadSize += length;                        //发送进度                        publishProgress(downloadSize * 100 / contentLength);                    }                    inputStream.close();                    outputStream.close();                } catch (MalformedURLException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                    return false;                }            } else {                return false;            }            return true;        }        @Override        protected void onPostExecute(Boolean aBoolean) {            super.onPostExecute(aBoolean);            //在UI线程中，执行结果 处理            mDownloadButton.setText(aBoolean ? getString(R.string.download_finish) : getString(R.string.download_fail));            mResultTextView.setText(aBoolean ? getString(R.string.download_finish) + mFilePath : getString(R.string.download_fail));        }        @Override        protected void onProgressUpdate(Integer... values) {            super.onProgressUpdate(values);            //收到进度，然后处理：  在UI线程中            if (values != null && values.length > 0) {                mProgressBar.setProgress(values[0]);            }        }    }}