Android中检查更新APK，以及下载APK安装。

                APK检查更新，代码如下：

 /**
     * 版本更新
     */
    // 下载进度条
    private ProgressBar progressBar;
    // 是否终止下载
    private boolean isInterceptDownload = false;
    //进度条显示数值
    private int progress = 0;
    //获取的下载链接
    private String apkDwonloadUrl = "";
    private String netVercode;
    private String disableCode;
    private int localVercode;
    private String updateFunction;
    /**
     * 声明一个handler来跟进进度条
     */
    private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            switch (msg.what) {
                case 0x111:
                    // 更新进度情况
                    progressBar.setProgress(progress);
                    break;
                case 0x222:
                    progressBar.setVisibility(View.INVISIBLE);
                    // 安装apk文件
                    installApk();
                    break;
                default:
                    break;
            }
        }
    };

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        inHandler();
    }

    /**
     * 进入当前页面后5分钟开始检测版本(时间可自定义)
     */
    private void inHandler() {
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                doCheckVersion();//自动检测版本更新
            }
        }, 100000 * 3);
    }

    /**
     * 版本更新请求
     */
    private void doCheckVersion() {
        //如果当前的版本号小于服务器的版本号就弹出版本更新dialog
        if (netVercode > localVercode) {
            LogUtils.d("版本需要更新");
            showUpdateDialog();
        } else {
            LogUtils.d("此版本为最新版本，无需更新");
        }
    }

    /**
     * 提示更新对话框
     * 

     * 版本信息对象
     */
    private void showUpdateDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setTitle(R.string.versionUpdate);
        builder.setMessage(updateFunction);
        builder.setCancelable(false);
        builder.setPositiveButton(R.string.download, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                // 弹出下载框
                showDownloadDialog();
            }
        });
        builder.setNegativeButton(R.string.talkLater, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        builder.create().show();
    }

    /**
     * 弹出下载框
     */
    private void showDownloadDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setTitle(R.string.versionUpdateing);
        builder.setCancelable(false);
        final LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
        View v = inflater.inflate(R.layout.activity_update_prgress, null);
        progressBar = (ProgressBar) v.findViewById(R.id.pb_update_progress);
        builder.setView(v);
        builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                //终止下载
                isInterceptDownload = true;
            }
        });
        builder.create().show();
        //下载apk
        downloadApk();
    }


    /**
     * 下载apk
     */
    private void downloadApk() {
        //开启另一线程下载
        Thread downLoadThread = new Thread(downApkRunnable);
        downLoadThread.start();
    }

    /**
     * 从服务器下载新版apk的线程
     */
    private Runnable downApkRunnable = new Runnable() {
        @Override
        public void run() {
            if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                //如果没有SD卡
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setTitle(R.string.houseKeeperHint);
                builder.setMessage(R.string.loadHintInfo);
                builder.setPositiveButton(R.string.sure, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
                builder.show();
            } else {
                try {
                    //服务器上新版apk地址
                    java.net.URL url = new java.net.URL(apkDwonloadUrl);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.connect();
                    int length = conn.getContentLength();
                    InputStream is = conn.getInputStream();
                    File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/updateApkFile/");
                    if (!file.exists()) {
                        //如果文件夹不存在,则创建
                        file.mkdir();
                    }
                    //下载服务器中新版本软件（写文件）
                    String apkFile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/updateApkFile/" +
                            AppUtils.getVersionName(MainActivity.this);
                    File ApkFile = new File(apkFile);
                    FileOutputStream fos = new FileOutputStream(ApkFile);
                    int count = 0;
                    byte buf[] = new byte[1024];
                    do {
                        int numRead = is.read(buf);
                        count += numRead;
                        //更新进度条
                        progress = (int) (((float) count / length) * 100);
//                        handler.sendEmptyMessage(1);
                        android.os.Message message_ = new android.os.Message();
                        message_.what = 0x111;
                        handler.sendMessage(message_);
                        if (numRead <= 0) {
                            //下载完成通知安装
//                            handler.sendEmptyMessage(0);
                            android.os.Message message = new android.os.Message();
                            message.what = 0x222;
                            handler.sendMessage(message);
                            break;
                        }
                        fos.write(buf, 0, numRead);
                        //当点击取消时，则停止下载
                    } while (!isInterceptDownload);
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    };

    /**
     * 安装apk
     */
    private void installApk() {
        // 获取当前sdcard存储路径
        File apkFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/updateApkFile/" +
                AppUtils.getVersionName(MainActivity.this));
        if (!apkFile.exists()) {
            return;
        }
        Intent i = new Intent(Intent.ACTION_VIEW);
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        // 安装，如果签名不一致，可能出现程序未安装提示
        i.setDataAndType(Uri.fromFile(new File(apkFile.getAbsolutePath())), "application/vnd.android.package-archive");
        MainActivity.this.startActivity(i);
        android.os.Process.killProcess(android.os.Process.myPid());

    }

              权限管理：

//读写权限

private static String[] PERMISSIONS_STORAGE = {
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE};

//判断是否含有权限
boolean hasPermission = PermissionsManager.getInstance()
        .hasAllPermissions(SettingActivity.this, PERMISSIONS_STORAGE);
if (hasPermission) {
    //含有权限，访问
    showUpdateDialog();
} else {
    //不含权限，弹出开启权限窗
    PermissionsManager.getInstance().
            requestPermissionsIfNecessaryForResult(SettingActivity.this,
                    PERMISSIONS_STORAGE, new PermissionsResultAction() {
                        //同意开启权限
                        @Override
                        public void onGranted() {
                            LogUtils.i(TAG + "同意开启权限");
                            showUpdateDialog();
                        }

                        //拒绝开启权限
                        @Override
                        public void onDenied(String permission) {
                            String message = String.format(Locale.getDefault(), "该权限是必须权限,不开启将影响APP使用", permission);
                            Toast.makeText(SettingActivity.this, message, Toast.LENGTH_SHORT).show();
                        }
                    }
            );
}

    //权限管理工具类

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.Fragment;
import android.util.Log;

import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/**
 * Created by xiaoMan on 2016/9/18.
 * detail:A class to help you manage your permissions simply.
 * 权限管理工具类
 */
public class PermissionsManager {

    private static final String TAG = PermissionsManager.class.getSimpleName();

    private final Set mPendingRequests = new HashSet<>(1);
    private final Set mPermissions = new HashSet<>(1);
    private final List> mPendingActions = new ArrayList<>(1);

    private static PermissionsManager mInstance = null;

    public static PermissionsManager getInstance() {
        if (mInstance == null) {
            mInstance = new PermissionsManager();
        }
        return mInstance;
    }

    private PermissionsManager() {
        initializePermissionsMap();
    }

    /**
     * This method uses reflection to read all the permissions in the Manifest class.
     * This is necessary because some permissions do not exist on older versions of Android,
     * since they do not exist, they will be denied when you check whether you have permission
     * which is problematic since a new permission is often added where there was no previous
     * permission required. We initialize a Set of available permissions and check the set
     * when checking if we have permission since we want to know when we are denied a permission
     * because it doesn't exist yet.
     */
    private synchronized void initializePermissionsMap() {
        Field[] fields = Manifest.permission.class.getFields();
        for (Field field : fields) {
            String name = null;
            try {
                name = (String) field.get("");
            } catch (IllegalAccessException e) {
                Log.e(TAG, "Could not access field", e);
            }
            mPermissions.add(name);
        }
    }

    /**
     * This method retrieves all the permissions declared in the application's manifest.
     * It returns a non null array of permisions that can be declared.
     *
     * @param activity the Activity necessary to check what permissions we have.
     * @return a non null array of permissions that are declared in the application manifest.
     */
    @NonNull
    private synchronized String[] getManifestPermissions(@NonNull final Activity activity) {
        PackageInfo packageInfo = null;
        List list = new ArrayList<>(1);
        try {
            Log.d(TAG, activity.getPackageName());
            packageInfo = activity.getPackageManager().getPackageInfo(activity.getPackageName(), PackageManager.GET_PERMISSIONS);
        } catch (PackageManager.NameNotFoundException e) {
            Log.e(TAG, "A problem occurred when retrieving permissions", e);
        }
        if (packageInfo != null) {
            String[] permissions = packageInfo.requestedPermissions;
            if (permissions != null) {
                for (String perm : permissions) {
                    Log.d(TAG, "Manifest contained permission: " + perm);
                    list.add(perm);
                }
            }
        }
        return list.toArray(new String[list.size()]);
    }

    /**
     * This method adds the {@link PermissionsResultAction} to the current list
     * of pending actions that will be completed when the permissions are
     * received. The list of permissions passed to this method are registered
     * in the PermissionsResultAction object so that it will be notified of changes
     * made to these permissions.
     *
     * @param permissions the required permissions for the action to be executed.
     * @param action      the action to add to the current list of pending actions.
     */
    private synchronized void addPendingAction(@NonNull String[] permissions,
                                               @Nullable PermissionsResultAction action) {
        if (action == null) {
            return;
        }
        action.registerPermissions(permissions);
        mPendingActions.add(new WeakReference<>(action));
    }

    /**
     * This method removes a pending action from the list of pending actions.
     * It is used for cases where the permission has already been granted, so
     * you immediately wish to remove the pending action from the queue and
     * execute the action.
     *
     * @param action the action to remove
     */
    private synchronized void removePendingAction(@Nullable PermissionsResultAction action) {
        for (Iterator> iterator = mPendingActions.iterator();
             iterator.hasNext(); ) {
            WeakReference weakRef = iterator.next();
            if (weakRef.get() == action || weakRef.get() == null) {
                iterator.remove();
            }
        }
    }

    /**
     * This static method can be used to check whether or not you have a specific permission.
     * It is basically a less verbose method of using {@link ActivityCompat#checkSelfPermission(Context, String)}
     * and will simply return a boolean whether or not you have the permission. If you pass
     * in a null Context object, it will return false as otherwise it cannot check the permission.
     * However, the Activity parameter is nullable so that you can pass in a reference that you
     * are not always sure will be valid or not (e.g. getActivity() from Fragment).
     *
     * @param context    the Context necessary to check the permission
     * @param permission the permission to check
     * @return true if you have been granted the permission, false otherwise
     */
    @SuppressWarnings("unused")
    public synchronized boolean hasPermission(@Nullable Context context, @NonNull String permission) {
        return context != null && (ActivityCompat.checkSelfPermission(context, permission)
                == PackageManager.PERMISSION_GRANTED || !mPermissions.contains(permission));
    }

    /**
     * This static method can be used to check whether or not you have several specific permissions.
     * It is simpler than checking using {@link ActivityCompat#checkSelfPermission(Context, String)}
     * for each permission and will simply return a boolean whether or not you have all the permissions.
     * If you pass in a null Context object, it will return false as otherwise it cannot check the
     * permission. However, the Activity parameter is nullable so that you can pass in a reference
     * that you are not always sure will be valid or not (e.g. getActivity() from Fragment).
     *
     * @param context     the Context necessary to check the permission
     * @param permissions the permissions to check
     * @return true if you have been granted all the permissions, false otherwise
     */
    @SuppressWarnings("unused")
    public synchronized boolean hasAllPermissions(@Nullable Context context, @NonNull String[] permissions) {
        if (context == null) {
            return false;
        }
        boolean hasAllPermissions = true;
        for (String perm : permissions) {
            hasAllPermissions &= hasPermission(context, perm);
        }
        return hasAllPermissions;
    }

    /**
     * This method will request all the permissions declared in your application manifest
     * for the specified {@link PermissionsResultAction}. The purpose of this method is to enable
     * all permissions to be requested at one shot. The PermissionsResultAction is used to notify
     * you of the user allowing or denying each permission. The Activity and PermissionsResultAction
     * parameters are both annotated Nullable, but this method will not work if the Activity
     * is null. It is only annotated Nullable as a courtesy to prevent crashes in the case
     * that you call this from a Fragment where {@link Fragment#getActivity()} could yield
     * null. Additionally, you will not receive any notification of permissions being granted
     * if you provide a null PermissionsResultAction.
     *
     * @param activity the Activity necessary to request and check permissions.
     * @param action   the PermissionsResultAction used to notify you of permissions being accepted.
     */
    @SuppressWarnings("unused")
    public synchronized void requestAllManifestPermissionsIfNecessary(final @Nullable Activity activity,
                                                                      final @Nullable PermissionsResultAction action) {
        if (activity == null) {
            return;
        }
        String[] perms = getManifestPermissions(activity);
        requestPermissionsIfNecessaryForResult(activity, perms, action);
    }

    /**
     * This method should be used to execute a {@link PermissionsResultAction} for the array
     * of permissions passed to this method. This method will request the permissions if
     * they need to be requested (i.e. we don't have permission yet) and will add the
     * PermissionsResultAction to the queue to be notified of permissions being granted or
     * denied. In the case of pre-Android Marshmallow, permissions will be granted immediately.
     * The Activity variable is nullable, but if it is null, the method will fail to execute.
     * This is only nullable as a courtesy for Fragments where getActivity() may yeild null
     * if the Fragment is not currently added to its parent Activity.
     *
     * @param activity    the activity necessary to request the permissions.
     * @param permissions the list of permissions to request for the {@link PermissionsResultAction}.
     * @param action      the PermissionsResultAction to notify when the permissions are granted or denied.
     */
    @SuppressWarnings("unused")
    public synchronized void requestPermissionsIfNecessaryForResult(@Nullable Activity activity,
                                                                    @NonNull String[] permissions,
                                                                    @Nullable PermissionsResultAction action) {
        if (activity == null) {
            return;
        }
        addPendingAction(permissions, action);
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            doPermissionWorkBeforeAndroidM(activity, permissions, action);
        } else {
            List permList = getPermissionsListToRequest(activity, permissions, action);
            if (permList.isEmpty()) {
                //if there is no permission to request, there is no reason to keep the action int the list
                removePendingAction(action);
            } else {
                String[] permsToRequest = permList.toArray(new String[permList.size()]);
                mPendingRequests.addAll(permList);
                ActivityCompat.requestPermissions(activity, permsToRequest, 1);
            }
        }
    }

    /**
     * This method should be used to execute a {@link PermissionsResultAction} for the array
     * of permissions passed to this method. This method will request the permissions if
     * they need to be requested (i.e. we don't have permission yet) and will add the
     * PermissionsResultAction to the queue to be notified of permissions being granted or
     * denied. In the case of pre-Android Marshmallow, permissions will be granted immediately.
     * The Fragment variable is used, but if {@link Fragment#getActivity()} returns null, this method
     * will fail to work as the activity reference is necessary to check for permissions.
     *
     * @param fragment    the fragment necessary to request the permissions.
     * @param permissions the list of permissions to request for the {@link PermissionsResultAction}.
     * @param action      the PermissionsResultAction to notify when the permissions are granted or denied.
     */
    @SuppressWarnings("unused")
    public synchronized void requestPermissionsIfNecessaryForResult(@NonNull Fragment fragment,
                                                                    @NonNull String[] permissions,
                                                                    @Nullable PermissionsResultAction action) {
        Activity activity = fragment.getActivity();
        if (activity == null) {
            return;
        }
        addPendingAction(permissions, action);
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            doPermissionWorkBeforeAndroidM(activity, permissions, action);
        } else {
            List permList = getPermissionsListToRequest(activity, permissions, action);
            if (permList.isEmpty()) {
                //if there is no permission to request, there is no reason to keep the action int the list
                removePendingAction(action);
            } else {
                String[] permsToRequest = permList.toArray(new String[permList.size()]);
                mPendingRequests.addAll(permList);
                fragment.requestPermissions(permsToRequest, 1);
            }
        }
    }

    /**
     * This method notifies the PermissionsManager that the permissions have change. If you are making
     * the permissions requests using an Activity, then this method should be called from the
     * Activity callback onRequestPermissionsResult() with the variables passed to that method. If
     * you are passing a Fragment to make the permissions request, then you should call this in
     * the {@link Fragment#onRequestPermissionsResult(int, String[], int[])} method.
     * It will notify all the pending PermissionsResultAction objects currently
     * in the queue, and will remove the permissions request from the list of pending requests.
     *
     * @param permissions the permissions that have changed.
     * @param results     the values for each permission.
     */
    @SuppressWarnings("unused")
    public synchronized void notifyPermissionsChange(@NonNull String[] permissions, @NonNull int[] results) {
        int size = permissions.length;
        if (results.length < size) {
            size = results.length;
        }
        Iterator> iterator = mPendingActions.iterator();
        while (iterator.hasNext()) {
            PermissionsResultAction action = iterator.next().get();
            for (int n = 0; n < size; n++) {
                if (action == null || action.onResult(permissions[n], results[n])) {
                    iterator.remove();
                    break;
                }
            }
        }
        for (int n = 0; n < size; n++) {
            mPendingRequests.remove(permissions[n]);
        }
    }

    /**
     * When request permissions on devices before Android M (Android 6.0, API Level 23)
     * Do the granted or denied work directly according to the permission status
     *
     * @param activity    the activity to check permissions
     * @param permissions the permissions names
     * @param action      the callback work object, containing what we what to do after
     *                    permission check
     */
    private void doPermissionWorkBeforeAndroidM(@NonNull Activity activity,
                                                @NonNull String[] permissions,
                                                @Nullable PermissionsResultAction action) {
        for (String perm : permissions) {
            if (action != null) {
                if (!mPermissions.contains(perm)) {
                    action.onResult(perm, Permissions.NOT_FOUND);
                } else if (ActivityCompat.checkSelfPermission(activity, perm)
                        != PackageManager.PERMISSION_GRANTED) {
                    action.onResult(perm, Permissions.DENIED);
                } else {
                    action.onResult(perm, Permissions.GRANTED);
                }
            }
        }
    }

    /**
     * Filter the permissions list:
     * If a permission is not granted, add it to the result list
     * if a permission is granted, do the granted work, do not add it to the result list
     *
     * @param activity    the activity to check permissions
     * @param permissions all the permissions names
     * @param action      the callback work object, containing what we what to do after
     *                    permission check
     * @return a list of permissions names that are not granted yet
     */
    @NonNull
    private List getPermissionsListToRequest(@NonNull Activity activity,
                                                     @NonNull String[] permissions,
                                                     @Nullable PermissionsResultAction action) {
        List permList = new ArrayList<>(permissions.length);
        for (String perm : permissions) {
            if (!mPermissions.contains(perm)) {
                if (action != null) {
                    action.onResult(perm, Permissions.NOT_FOUND);
                }
            } else if (ActivityCompat.checkSelfPermission(activity, perm) != PackageManager.PERMISSION_GRANTED) {
                if (!mPendingRequests.contains(perm)) {
                    permList.add(perm);
                }
            } else {
                if (action != null) {
                    action.onResult(perm, Permissions.GRANTED);
                }
            }
        }
        return permList;
    }

}

       布局：activity_update_prgress.xml

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


            android:id="@+id/pb_update_progress"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="@dimen/x60"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:layout_marginTop="30dp"
        android:indeterminate="false"
        android:max="100"
        android:progressDrawable="@drawable/progressbar_color" />

            progressbar_color.xml-------->

xml version="1.0" encoding="utf-8"?>
xmlns:android="http://schemas.android.com/apk/res/android">
    android:id="@android:id/background">
        
            android:radius="5dp" />

            android:color="@color/colorLine" />
        
    
    
            android:id="@android:id/progress"
        android:drawable="@drawable/update_progress">
        
            android:radius="5dp" />