示例：

零、准备工作

0.1第三方库

implementation ‘io.reactivex.rxjava2:rxjava:2.2.2’
implementation ‘io.reactivex.rxjava2:rxandroid:2.1.0’
implementation ‘io.reactivex.rxjava2:rxkotlin:2.3.0’
implementation ‘com.squareup.okhttp3:okhttp:3.11.0’
implementation ‘com.squareup.okio:okio:2.0.0’

0.2权限

<uses-permission android:name="android.permission.INTERNET" />
<!-- 写入权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

0.3格式

“Code”: 0,
“Msg”: “”,
“UpdateStatus”: 1,
“VersionCode”: 3,
“VersionName”: “1.0.2”,
“ModifyContent”: “1、优化api接口。\r\n2、添加使用demo演示。\r\n3、新增自定义更新服务API接口。\r\n4、优化更新提示界面。”,
“DownloadUrl”: “https://raw.githubusercontent.com/xuexiangjys/XUpdate/master/apk/xupdate_demo_1.0.2.apk”,
“ApkSize”: 2048
“ApkMd5”: “…” //md5值没有的话，就无法保证apk是否完整，每次都会重新下载。

一、检测是否是最新版本，不是则更新

private Disposable downDisposable;
private ProgressBar progressBar;
private TextView textView4;
private Button upgrade;
private long downloadLength=0;
private long contentLength=0;
private String[] PERMISSIONS_STORAGE = {
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE};

//判断版本是否最新，如果不是最新版本则更新

private void test(){
        Observable.create(new ObservableOnSubscribe<String>() {
            @Override
            public void subscribe(ObservableEmitter<String> emitter) throws Exception {
                OkHttpClient client = new OkHttpClient();
                Request request = new Request.Builder()
                        .url("url")
                        .build();

                client.newCall(request).enqueue(new okhttp3.Callback() {
                    @Override
                    public void onFailure(Call call, IOException e) {
                        emitter.onError(e);
                    }

                    @Override
                    public void onResponse(Call call, Response response) throws IOException {
                        String result="";
                        if (response.body()!=null) {
                            result=response.body().string();
                        }else {
                            //返回数据错误
                            return;
                        }
                        emitter.onNext(result);
                    }
                });
//                emitter.onNext("123");
            }
        }).subscribeOn(Schedulers.io())// 将被观察者切换到子线程
                .observeOn(AndroidSchedulers.mainThread())// 将观察者切换到主线程
                .subscribe(new Observer<String>() {
                    private Disposable mDisposable;
                    @Override
                    public void onSubscribe(Disposable d) {
                        mDisposable = d;
                    }
                    @Override
                    public void onNext(String result) {
                        if (result.isEmpty()){
                            return;
                        }
                        //2.判断版本是否最新，如果不是最新版本则更新
                        String downloadUrl="https://raw.githubusercontent.com/xuexiangjys/XUpdate/master/apk/xupdate_demo_1.0.2.apk";
                        String title="是否升级到4.1.1版本？";
                        String size="新版本大小：未知";
                        String msg="1、优化api接口。\r\n2、添加使用demo演示。\r\n3、新增自定义更新服务API接口。\r\n4、优化更新提示界面。";
                        int versionCode=20000;
                        try {
                            int version = getPackageManager().
                                    getPackageInfo(getPackageName(), 0).versionCode;
                            if (versionCode>version){
                                LayoutInflater inflater = LayoutInflater.from(TestActivity.this);
                                View view = inflater.inflate(R.layout.layout_dialog, null);
                                AlertDialog.Builder mDialog = new AlertDialog.Builder(TestActivity.this,R.style.Translucent_NoTitle);
                                mDialog.setView(view);
                                mDialog.setCancelable(true);
                                mDialog.setOnKeyListener(new DialogInterface.OnKeyListener() {
                                    @Override
                                    public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                                        return keyCode == KeyEvent.KEYCODE_BACK;
                                    }
                                });
                                upgrade= view.findViewById(R.id.button);
                                TextView textView1= view.findViewById(R.id.textView1);
                                TextView textView2= view.findViewById(R.id.textView2);
                                TextView textView3= view.findViewById(R.id.textView3);
                                textView4= view.findViewById(R.id.textView4);
                                ImageView iv_close= view.findViewById(R.id.iv_close);
                                progressBar= view.findViewById(R.id.progressBar);
                                progressBar.setMax(100);
                                textView1.setText(title);
                                textView2.setText(size);
                                textView3.setText(msg);
                                upgrade.setOnClickListener(new View.OnClickListener() {
                                    @Override
                                    public void onClick(View v) {
                                        //动态询问是否授权
                                        int permission = ActivityCompat.checkSelfPermission(getApplication(),
                                            Manifest.permission.WRITE_EXTERNAL_STORAGE);
                                        if (permission != PackageManager.PERMISSION_GRANTED) {
                                            ActivityCompat.requestPermissions(TestActivity.this, PERMISSIONS_STORAGE,
                                                1);
                                        }else {
                                            upgrade.setVisibility(View.INVISIBLE);
                                            down(downloadUrl);
                                        }
                                    }
                                });
                                iv_close.setOnClickListener(new View.OnClickListener() {
                                    @Override
                                    public void onClick(View v) {
                                        finish();
                                    }
                                });
                                mDialog.show();
                            }else {

                            }
                        } catch (PackageManager.NameNotFoundException e) {
                            e.printStackTrace();
                        }
                        mDisposable.dispose();
                    }
                    @Override
                    public void onError(Throwable e) {
                        test();
                    }
                    @Override
                    public void onComplete() {

                    }
                });
    }

//下载apk并更新进度条

private void down(String downloadUrl){
        Observable.create(new ObservableOnSubscribe<Integer>() {
            @Override
            public void subscribe(ObservableEmitter<Integer> emitter) throws Exception {
                downApk(downloadUrl,emitter);
            }
        }).subscribeOn(Schedulers.io())// 将被观察者切换到子线程
                .observeOn(AndroidSchedulers.mainThread())// 将观察者切换到主线程
                .subscribe(new Observer<Integer>() {

                    @Override
                    public void onSubscribe(Disposable d) {
                        downDisposable = d;
                    }
                    @Override
                    public void onNext(Integer result) {
                        //设置ProgressDialog 进度条进度
                        progressBar.setProgress(result);
                        textView4.setText(result+"%");
                    }
                    @Override
                    public void onError(Throwable e) {
                        Toast.makeText(getApplication(),"网络异常！请重新下载！",Toast.LENGTH_SHORT).show();
                        upgrade.setEnabled(true);
                    }
                    @Override
                    public void onComplete() {
                        Toast.makeText(getApplication(),"服务器异常！请重新下载！",Toast.LENGTH_SHORT).show();
                        upgrade.setEnabled(true);
                    }
                });
    }

二、下载apk

//下载apk

private void downApk(String downloadUrl,ObservableEmitter<Integer> emitter){
    OkHttpClient client = new OkHttpClient();
    Request request = new Request.Builder()
            .url(downloadUrl)
            .build();
    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
            //下载失败
            breakpoint(downloadUrl,emitter);
        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            if (response.body() == null) {
                //下载失败
                breakpoint(downloadUrl,emitter);
                return;
            }
            InputStream is = null;
            FileOutputStream fos = null;
            byte[] buff = new byte[2048];
            int len;
            try {
                is = response.body().byteStream();
                File file = createFile();
                fos = new FileOutputStream(file);
                long total = response.body().contentLength();
                contentLength=total;
                long sum = 0;
                while ((len = is.read(buff)) != -1) {
                    fos.write(buff,0,len);
                    sum+=len;
                    int progress = (int) (sum * 1.0f / total * 100);
                    //下载中，更新下载进度
                    emitter.onNext(progress);
                    downloadLength=sum;
                }
                fos.flush();
                //4.下载完成，安装apk
                installApk(TestActivity.this,file);
            } catch (Exception e) {
                e.printStackTrace();
                breakpoint(downloadUrl,emitter);
            } finally {
                try {
                    if (is != null)
                        is.close();
                    if (fos != null)
                        fos.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    });

}

//断点续传

private void breakpoint(String downloadUrl,ObservableEmitter<Integer> emitter){
    OkHttpClient client = new OkHttpClient();
    Request request = new Request.Builder()
            .url(downloadUrl)
            .addHeader("RANGE", "bytes=" + downloadLength + "-" + contentLength)
            .build();
    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
            //下载失败
            breakpoint(downloadUrl,emitter);
        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            if (response.body() == null) {
                //下载失败
                breakpoint(downloadUrl,emitter);
                return;
            }
            InputStream is = null;
            RandomAccessFile randomFile = null;
            byte[] buff = new byte[2048];
            int len;
            try {
                is = response.body().byteStream();
                String root = Environment.getExternalStorageDirectory().getPath();
                File file = new File(root,"updateDemo.apk");
                randomFile = new RandomAccessFile(file, "rwd");
                randomFile.seek(downloadLength);
                long total = contentLength;
                long sum = downloadLength;
                while ((len = is.read(buff)) != -1) {
                    randomFile.write(buff,0,len);
                    sum+=len;
                    int progress = (int) (sum * 1.0f / total * 100);
                    //下载中，更新下载进度
                    emitter.onNext(progress);
                    downloadLength=sum;
                }
                //4.下载完成，安装apk
                installApk(TestActivity.this,file);
            } catch (Exception e) {
                e.printStackTrace();
                breakpoint(downloadUrl,emitter);
            } finally {
                try {
                    if (is != null)
                        is.close();
                    if (randomFile != null)
                        randomFile.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    });
}

/**

• 路径为根目录
• 创建文件名称为 updateDemo.apk
  */

private File createFile() {
    String root = Environment.getExternalStorageDirectory().getPath();
    File file = new File(root,"updateDemo.apk");
    if (file.exists())
        file.delete();
    try {
        file.createNewFile();
        return file;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null ;
}

三、安装apk

3.1项目的src/res新建个xml文件夹再自定义一个file_paths文件

<?xml version="1.0" encoding="utf-8"?>
<paths  xmlns:android="http://schemas.android.com/apk/res/android">
    <files-path name="name1" path="test1" />
</paths>

3.2在清单文件中配置

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="com.mydomain.fileprovider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/file_paths" />
</provider>

3.3安装apk

//安装apk，包含7.0

public void installApk(Context context, File file) {
    if (context == null) {
        return;
    }
    String authority = getApplicationContext().getPackageName() + ".fileProvider";
    Uri apkUri = FileProvider.getUriForFile(context, authority, file);
    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    //判读版本是否在7.0以上
    if (Build.VERSION.SDK_INT >= 24) {
        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        intent.setDataAndType(apkUri, "application/vnd.android.package-archive");
    } else {
        intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
    }

    context.startActivity(intent);
    //弹出安装窗口把原程序关闭。
    //避免安装完毕点击打开时没反应
    Process.killProcess(android.os.Process.myPid());
}

四、取消订阅

@Override
protected void onDestroy() {
    super.onDestroy();
    downDisposable.dispose();//取消订阅
}

五、自定义Dialog

5.1UI

见一、检测是否是最新版本，不是则更新

5.2布局

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

<android.support.constraint.ConstraintLayout xmlns:android=“http://schemas.android.com/apk/res/android”
xmlns:app=“http://schemas.android.com/apk/res-auto”
xmlns:tools=“http://schemas.android.com/tools”
android:layout_width=“match_parent”
android:layout_height=“match_parent”>

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/lib_update_app_top_bg"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<View
    android:id="@+id/view"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:background="@drawable/lib_update_app_info_bg"
    app:layout_constraintBottom_toTopOf="@+id/line"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/imageView1" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="16dp"
    android:layout_marginTop="16dp"
    android:text="是否升级到1.0版本？"
    android:textColor="@android:color/black"
    android:textSize="15sp"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/imageView1" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="16dp"
    android:layout_marginTop="16dp"
    android:text="新版本大小："
    android:textColor="#666"
    android:textSize="14sp"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView1" />


<ScrollView
    android:id="@+id/scrollView2"
    android:layout_width="0dp"
    android:layout_height="60dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="16dp"
    android:layout_marginEnd="16dp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/textView2">

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

        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1，xxxxxxxx\n2，ooooooooo"
            android:textColor="#666"
            android:textSize="14sp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView2" />
    </LinearLayout>
</ScrollView>

<Button
    android:id="@+id/button"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginTop="16dp"
    android:layout_marginEnd="16dp"
    android:background="@drawable/textview_round_red"
    android:gravity="center"
    android:minHeight="40dp"
    android:text="升级"
    android:textColor="@android:color/white"
    android:textSize="15sp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/scrollView2" />

<ProgressBar
    android:id="@+id/progressBar"
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginStart="16dp"
    android:layout_marginEnd="16dp"
    app:layout_constraintBottom_toBottomOf="@+id/button"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="0%"
    android:textColor="#E94339"
    app:layout_constraintBottom_toTopOf="@+id/progressBar"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent" />

<android.support.constraint.Guideline
    android:id="@+id/guideline1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    app:layout_constraintGuide_percent="0.5" />

<View
    android:id="@+id/line"
    android:layout_width="1dp"
    android:layout_height="50dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="16dp"
    android:layout_marginEnd="8dp"
    android:background="#d8d8d8"
    android:visibility="visible"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.501"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/button" />

<ImageView
    android:id="@+id/iv_close"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp"
    android:src="@mipmap/lib_update_app_close"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/line" />

<android.support.constraint.Guideline
    android:id="@+id/guideline2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    app:layout_constraintGuide_percent="0.2" />

</android.support.constraint.ConstraintLayout>

5.3其他文件

5.3.1textview_round_red.xml

<?xml version="1.0" encoding="utf-8"?>
<shape  xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- view背景色 -->
    <solid android:color="#E94339" />
    <!-- 边框颜色 宽度 -->
    <stroke
        android:width="1dip"
        android:color="#E94339" />
    <!-- 边框圆角 -->
    <corners
        android:bottomRightRadius="5dp"
        android:topRightRadius="5dp"
        android:bottomLeftRadius="5dp"
        android:topLeftRadius="5dp"/>
</shape >

5.3.2lib_update_app_info_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
       android:shape="rectangle">
    <corners
        android:bottomLeftRadius="5dp"
        android:bottomRightRadius="5dp"/>
    <solid android:color="@android:color/white"/>
</shape>

5.3.3styles文件

<style name="Translucent_NoTitle" parent="android:style/Theme.Dialog">

    <item name="android:background">#00000000</item> <!-- 设置自定义布局的背景透明 -->
    <item name="android:windowBackground">@android:color/transparent</item>  <!-- 设置window背景透明，也就是去边框 -->
</style>

5.4图片