DownLoad--OKHttp3

使用OKHttp3进行下载和断点续传；（详细内容，请下载源码）

文件的存储和写入；

 // 写文件到本地
         try {
             is = response.body().byteStream();
             fileOutputStream = new FileOutputStream(file, true);
             byte[] buffer = new byte[2048];//缓冲数组2kB

             int len;
             while ((len = is.read(buffer)) != -1) {
                 fileOutputStream.write(buffer, 0, len);
                 downloadLength += len;

                 downloadInfo.setProgress(downloadLength);
                 e.onNext(downloadInfo);
             }

             fileOutputStream.flush();
             downCalls.remove(url);

         } finally {
             //关闭IO流
             IOUtil.closeAll(is, fileOutputStream);

         }

         e.onComplete();//完成

集成RXJava和RxAndroid进行线程切换；

  //RxJava和RxAndroid 用来做线程切换的
   compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
   compile 'io.reactivex.rxjava2:rxjava:2.0.1'

 // 下载
case R.id.main_btn_down3:
                DownloadManager.getInstance().download(url3, new DownLoadObserver() {
                    @Override
                    public void onNext(DownloadInfo value) {
                        super.onNext(value);

                        info3 = value;

                        // 设置进度
                        float v1 = value.getProgress() * 100 / value.getTotal();
                        progress3.setProgress((int) ++v1);
                    }

                    @Override
                    public void onComplete() {

                        if (downloadInfo != null) {
                            ToastUtils.showShort(mContext, downloadInfo.getFileName() + "下载完成");

                            // 调出安装界面
                            installAPK(downloadInfo);
                        }
                    }

                });
                break;

 // 取消3
            case R.id.main_btn_cancel3:
                DownloadManager.getInstance().cancel(url3);
                progress3.setProgress(0);
                // 删除本地文件
                DownloadManager.getInstance().deleteFile(info3);
                break;

 // 暂停3
            case R.id.main_btn_pause3:
                DownloadManager.getInstance().cancel(url3);
                break;

 ****************************************
 /**
  * 下载管理类
  */
 public class DownloadManager {

     private static final AtomicReference<DownloadManager> INSTANCE = new AtomicReference<>();
     private HashMap<String, Call> downCalls;//用来存放各个下载的请求
     private OkHttpClient mClient;//OKHttpClient;

     // 文件下载的保存路径
     public static final String apkPath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString();

     /**
      * 获得一个单例类
      *
      * @return
      */
     public static DownloadManager getInstance() {
         for (; ; ) {
             DownloadManager current = INSTANCE.get();

             if (current != null) {
                 return current;
             }
             current = new DownloadManager();

             if (INSTANCE.compareAndSet(null, current)) {
                 return current;
             }
         }
     }

     private DownloadManager() {
         downCalls = new HashMap<>();
         mClient = new OkHttpClient.Builder().build();
     }

     /**
      * 开始下载
      *
      * @param url              下载请求的网址
      * @param downLoadObserver 用来回调的接口
      */
     public void download(String url, DownLoadObserver downLoadObserver) {
         Observable.just(url)
                 .filter(s -> !downCalls.containsKey(s))//call的map已经有了,就证明正在下载,则这次不下载
                 .flatMap(s -> Observable.just(createDownInfo(s)))
                 .map(this::getRealFileName)//检测本地文件夹,生成新的文件名
                 .flatMap(downloadInfo -> Observable.create(new DownloadSubscribe(downloadInfo, downCalls, mClient)))//下载
                 .observeOn(AndroidSchedulers.mainThread())//在主线程回调
                 .subscribeOn(Schedulers.io())//在子线程执行
                 .subscribe(downLoadObserver);//添加观察者
     }

     /**
      * 取消
      *
      * @param url
      */
     public void cancel(String url) {
         Call call = downCalls.get(url);

         if (call != null) {
             call.cancel();
         }

         downCalls.remove(url);
     }

     /**
      * 取消后  删除本地下载文件
      *
      * @param info
      */
     public void deleteFile(DownloadInfo info) {
         String fileName = info.getFileName();
         File file = new File(apkPath, fileName);

         if (file.exists()) {
             file.delete();
         }
     }

     /**
      * 创建DownInfo
      *
      * @param url 请求网址
      * @return DownInfo
      */
     private DownloadInfo createDownInfo(String url) {
         DownloadInfo downloadInfo = new DownloadInfo(url);
         long contentLength = getContentLength(url);//获得文件大小
         downloadInfo.setTotal(contentLength);

         String fileName = url.substring(url.lastIndexOf("/"));
         downloadInfo.setFileName(fileName);
         return downloadInfo;
     }

     /**
      * 获取真实文件名
      *
      * @param downloadInfo
      * @return
      */
     private DownloadInfo getRealFileName(DownloadInfo downloadInfo) {

         String fileName = downloadInfo.getFileName();
         long downloadLength = 0, contentLength = downloadInfo.getTotal();

         File file = new File(apkPath, fileName);

         if (file.exists()) {
             //找到了文件,代表已经下载过,则获取其长度
             downloadLength = file.length();
         }

         //之前下载过,需要重新来一个文件
         int i = 1;
         while (downloadLength >= contentLength) {
             int dotIndex = fileName.lastIndexOf(".");
             String fileNameOther;

             if (dotIndex == -1) {
                 fileNameOther = fileName + "(" + i + ")";
             } else {
                 fileNameOther = fileName.substring(0, dotIndex)
                         + "(" + i + ")" + fileName.substring(dotIndex);
             }

             File newFile = new File(apkPath, fileNameOther);
             file = newFile;

             downloadLength = newFile.length();
             i++;
         }

         //设置改变过的文件名/大小
         downloadInfo.setProgress(downloadLength);
         downloadInfo.setFileName(file.getName());
         return downloadInfo;
     }

     /**
      * 获取下载长度
      *
      * @param downloadUrl
      * @return
      */
     private long getContentLength(String downloadUrl) {
         Request request = new Request.Builder()
                 .url(downloadUrl)
                 .build();

         try {
             Response response = mClient.newCall(request).execute();

             if (response != null && response.isSuccessful()) {
                 long contentLength = response.body().contentLength();
                 response.close();
                 return contentLength == 0 ? DownloadInfo.TOTAL_ERROR : contentLength;
             }
         } catch (IOException e) {
             e.printStackTrace();
         }

         return DownloadInfo.TOTAL_ERROR;
     }

 }

开启java8,使用Lambada表达式简化代码；

apply plugin: 'com.android.application'

android {
    compileSdkVersion 24
    buildToolsVersion "24.0.3"

    defaultConfig {
        applicationId "com.bill.download"
        minSdkVersion 15
        targetSdkVersion 24
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

        //为了开启Java8
        jackOptions {
            enabled true;
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    //开启Java1.8 能够使用lambda表达式
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])

    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })

    compile 'com.android.support:appcompat-v7:24.1.1'
    testCompile 'junit:junit:4.12'

    //OKHttp
    compile 'com.squareup.okhttp3:okhttp:3.6.0'

    //RxJava和RxAndroid 用来做线程切换的
    compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
    compile 'io.reactivex.rxjava2:rxjava:2.0.1'
}

下载完成的安装，增加7.0文件权限的判定；

 // 判断是否是7.0
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            Uri uriForFile = FileProvider.getUriForFile(mContext, "com.lanou3g.com.bill.downdemo.fileProvider", file); //在AndroidManifest中的android:authorities值

            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);//添加这一句表示对目标应用临时授权该Uri所代表的文件

            intent.setDataAndType(uriForFile, "application/vnd.android.package-archive");
            intent.setAction("android.intent.action.VIEW");
        } else {
            intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
            intent.setAction("android.intent.action.VIEW");
            intent.addCategory("android.intent.category.DEFAULT");
        }

自定义横向进度条；

/**
 * 自定义横向进度条 （仿鸿洋的）
 * Created by Bill on 2017/3/14.
 */

public class HorizontalProgressBarWithNumber extends ProgressBar {

    private static final int DEFAULT_TEXT_SIZE = 10;
    private static final int DEFAULT_TEXT_COLOR = 0XFFFC00D1;
    private static final int DEFAULT_COLOR_UNREACHED_COLOR = 0xFFd3d6da;
    private static final int DEFAULT_HEIGHT_REACHED_PROGRESS_BAR = 2;
    private static final int DEFAULT_HEIGHT_UNREACHED_PROGRESS_BAR = 2;
    private static final int DEFAULT_SIZE_TEXT_OFFSET = 10;

    /**
     * painter of all drawing things
     */
    protected Paint mPaint = new Paint();
    /**
     * color of progress number
     */
    protected int mTextColor = DEFAULT_TEXT_COLOR;
    /**
     * size of text (sp)
     */
    protected int mTextSize = sp2px(DEFAULT_TEXT_SIZE);

    /**
     * offset of draw progress
     */
    protected int mTextOffset = dp2px(DEFAULT_SIZE_TEXT_OFFSET);

    /**
     * height of reached progress bar
     */
    protected int mReachedProgressBarHeight = dp2px(DEFAULT_HEIGHT_REACHED_PROGRESS_BAR);

    /**
     * color of reached bar
     */
    protected int mReachedBarColor = DEFAULT_TEXT_COLOR;
    /**
     * color of unreached bar
     */
    protected int mUnReachedBarColor = DEFAULT_COLOR_UNREACHED_COLOR;
    /**
     * height of unreached progress bar
     */
    protected int mUnReachedProgressBarHeight = dp2px(DEFAULT_HEIGHT_UNREACHED_PROGRESS_BAR);
    /**
     * view width except padding
     */
    protected int mRealWidth;

    protected boolean mIfDrawText = true;

    protected static final int VISIBLE = 0;

    public HorizontalProgressBarWithNumber(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public HorizontalProgressBarWithNumber(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        obtainStyledAttributes(attrs);

        mPaint.setTextSize(mTextSize);
        mPaint.setColor(mTextColor);
    }

    @Override
    protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        int width = MeasureSpec.getSize(widthMeasureSpec);
        int height = measureHeight(heightMeasureSpec);
        setMeasuredDimension(width, height);

        mRealWidth = getMeasuredWidth() - getPaddingRight() - getPaddingLeft();
    }

    /**
     * 测量高度
     *
     * @param measureSpec
     * @return
     */
    private int measureHeight(int measureSpec) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        } else {
            float textHeight = (mPaint.descent() - mPaint.ascent());
            result = (int) (getPaddingTop() + getPaddingBottom() + Math.max(
                    Math.max(mReachedProgressBarHeight,
                            mUnReachedProgressBarHeight), Math.abs(textHeight)));
            if (specMode == MeasureSpec.AT_MOST) {
                result = Math.min(result, specSize);
            }
        }
        return result;
    }

    /**
     * 获取自定义属性
     *
     * @param attrs
     */
    private void obtainStyledAttributes(AttributeSet attrs) {
        // init values from custom attributes
        final TypedArray attributes = getContext().obtainStyledAttributes(
                attrs, R.styleable.HorizontalProgressBarWithNumber);

        mTextColor = attributes
                .getColor(
                        R.styleable.HorizontalProgressBarWithNumber_progress_text_color,
                        DEFAULT_TEXT_COLOR);
        mTextSize = (int) attributes.getDimension(
                R.styleable.HorizontalProgressBarWithNumber_progress_text_size,
                mTextSize);

        mReachedBarColor = attributes
                .getColor(
                        R.styleable.HorizontalProgressBarWithNumber_progress_reached_color,
                        mTextColor);
        mUnReachedBarColor = attributes
                .getColor(
                        R.styleable.HorizontalProgressBarWithNumber_progress_unreached_color,
                        DEFAULT_COLOR_UNREACHED_COLOR);
        mReachedProgressBarHeight = (int) attributes
                .getDimension(
                        R.styleable.HorizontalProgressBarWithNumber_progress_reached_bar_height,
                        mReachedProgressBarHeight);
        mUnReachedProgressBarHeight = (int) attributes
                .getDimension(
                        R.styleable.HorizontalProgressBarWithNumber_progress_unreached_bar_height,
                        mUnReachedProgressBarHeight);
        mTextOffset = (int) attributes
                .getDimension(
                        R.styleable.HorizontalProgressBarWithNumber_progress_text_offset,
                        mTextOffset);

        int textVisible = attributes
                .getInt(R.styleable.HorizontalProgressBarWithNumber_progress_text_visibility,
                        VISIBLE);
        if (textVisible != VISIBLE) {
            mIfDrawText = false;
        }
        attributes.recycle();
    }

    @Override
    protected synchronized void onDraw(Canvas canvas) {

        canvas.save();
        canvas.translate(getPaddingLeft(), getHeight() / 2);

        boolean noNeedBg = false;
        float radio = getProgress() * 1.0f / getMax();
        float progressPosX = (int) (mRealWidth * radio);
        String text = getProgress() + "%";
        // mPaint.getTextBounds(text, 0, text.length(), mTextBound);

        float textWidth = mPaint.measureText(text);
        float textHeight = (mPaint.descent() + mPaint.ascent()) / 2;

        if (progressPosX + textWidth > mRealWidth) {
            progressPosX = mRealWidth - textWidth;
            noNeedBg = true;
        }

        // draw reached bar
        float endX = progressPosX - mTextOffset / 2;
        if (endX > 0) {
            mPaint.setColor(mReachedBarColor);
            mPaint.setStrokeWidth(mReachedProgressBarHeight);
            canvas.drawLine(0, 0, endX, 0, mPaint);
        }
        // draw progress bar
        // measure text bound
        if (mIfDrawText) {
            mPaint.setColor(mTextColor);
            canvas.drawText(text, progressPosX, -textHeight, mPaint);
        }

        // draw unreached bar
        if (!noNeedBg) {
            float start = progressPosX + mTextOffset / 2 + textWidth;
            mPaint.setColor(mUnReachedBarColor);
            mPaint.setStrokeWidth(mUnReachedProgressBarHeight);
            canvas.drawLine(start, 0, mRealWidth, 0, mPaint);
        }

        canvas.restore();

    }

    /**
     * dp 2 px
     *
     * @param dpVal
     */
    protected int dp2px(int dpVal) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                dpVal, getResources().getDisplayMetrics());
    }

    /**
     * sp 2 px
     *
     * @param spVal
     * @return
     */
    protected int sp2px(int spVal) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
                spVal, getResources().getDisplayMetrics());
    }
}