【Android】应用程序后台转前台_android 将后台应用切到前台

需求：当应用在后台运行时，当有电话来的时候，需要切换到前台显示。

1.启动模式设置

android:launchMode="singleTask"
1

2.判断本应用是否已经位于最前端

 public static boolean isForeground(Context context) {
        ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<ActivityManager.RunningAppProcessInfo> appProcessInfoList = activityManager.getRunningAppProcesses();
        if (appProcessInfoList != null && appProcessInfoList.size() > 0) {
            //枚举进程
            for (ActivityManager.RunningAppProcessInfo appProcessInfo : appProcessInfoList) {
                if (appProcessInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    if (appProcessInfo.processName.equals(context.getApplicationInfo().processName)) {
                        return true;
                    }
                }
            }
        }
        return false;
    }
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

3.将本应用置顶到最前端

public static void setTopApp(Context context) {
        if (!isForeground(context)) {
            ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
            //获得当前运行的task(任务)
            List<ActivityManager.RunningTaskInfo> taskInfoList = activityManager.getRunningTasks(100);
            for (ActivityManager.RunningTaskInfo taskInfo : taskInfoList) {
                Log.e("MainActivity", "进程Task：" + taskInfo.topActivity.getPackageName());
                //找到本应用的 task，并将它切换到前台
                if (taskInfo.topActivity.getPackageName().equals(context.getPackageName())) {
                    activityManager.moveTaskToFront(taskInfo.id, 0);
                    break;
                }
            }
        }
    }
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

此时基本上实现了功能需求，网上教程基本上到这里也截止了，但是在尝试过后，很大可能是无法将应用从后台调转到前台的。因为现在手机版本高了，需要进行其他操作，申请悬浮窗权限.

4.悬浮窗权限

悬浮窗权限和其他权限不同，需要进行单独申请，申请时也要转到系统界面开启。

<!-- 悬浮窗 -->
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.SYSTEM_OVERLAY_WINDOW" />
1
2
3

5.自定义Dialog（用于权限申请）

/**
 * 确定对话框 单个按钮
 */
public class SingleDialog extends Dialog {

    private TextView dialog_message;
    private TextView dialog_ok;
    private Context mContext;
    private String tvMessage;
    private String tvOk;
    private OnClickListener onClickListener;

    public SingleDialog(Context context) {
        super(context);
    }

    public SingleDialog(Context context, String tvMessage, String tvBtn, OnClickListener onClickListenerPositive) {
        super(context);
        this.mContext = context;
        this.tvMessage = tvMessage;
        this.tvOk = tvBtn;
        this.onClickListener = onClickListenerPositive;
    }

    protected SingleDialog(Context context, boolean cancelable, @Nullable OnCancelListener cancelListener) {
        super(context, cancelable, cancelListener);
    }

    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.dialog_draw_over);
        dialog_message = findViewById(R.id.dialog_draw_message);
        dialog_ok = findViewById(R.id.dialog_draw_ok);

        Window dialogWindow = getWindow();
        WindowManager.LayoutParams lp = dialogWindow.getAttributes();
        DisplayMetrics d = mContext.getResources().getDisplayMetrics();
        lp.width = (int) (d.widthPixels * 0.7);
        lp.height = (int) (d.heightPixels * 0.7);
        dialogWindow.setAttributes(lp);
        dialogWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        SingleDialog.this.setCanceledOnTouchOutside(false);
        SingleDialog.this.setOnKeyListener(new OnKeyListener() {
            @Override
            public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_BACK) {
                    return true;
                } else {
                    return false;
                }
            }//屏蔽back键
        });
        dialog_message.setText(tvMessage);
        dialog_ok.setText(tvOk);
        dialog_ok.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onClickListener.onClick(SingleDialog.this, DialogInterface.BUTTON_POSITIVE);
            }
        });
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65

6.Dialog布局界面

<?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="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/dialog_draw_message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="30dp"
        android:layout_marginRight="20dp"
        android:layout_marginBottom="15dp"
        android:gravity="center"
        android:textColor="#090808"
        android:textSize="17sp" />

    <View
        android:layout_width="match_parent"
        android:layout_height="0.5dp"
        android:layout_marginTop="15dp"
        android:background="#090808" />

    <TextView
        android:id="@+id/dialog_draw_ok"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center"
        android:textColor="#090808"
        android:textSize="16sp" />

</LinearLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34

7.权限申请

public class OverPermissionUtil {

    //权限检测和申请
    public static void requestDrawOverlays(Activity activity) {
        if (!Settings.canDrawOverlays(activity)) {
            new SingleDialog(activity, "当前未获取悬浮窗权限", "去开启", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                    startActivityForResult(activity,
                            new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:" + activity.getPackageName())),
                            0, null);
                }
            }).show();
        }
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

8.应用后台转前台进程使用方式1

//因为调用一次可能调不过去，后台应用无法转前台应用，多调用几次就好了。
if (!ProcessUtil.isForeground(context)) {
    for (int i = 0; i < 10; i++) {
        if (ProcessUtil.isForeground(context)) {
             break;
        } else {
             ProcessUtil.setTopApp(context);
                }
        }
}
1
2
3
4
5
6
7
8
9
10

9.应用后台转前台进程使用方式2

//这一种方式代码少
Intent intent = context.getPackageManager().
                getLaunchIntentForPackage(context.getPackageName());
context.startActivity(intent);
1
2
3
4

注意：只有高版本手机上才会需要申请悬浮窗权限。