// in onCreate method
String appName = "Gmail";
String packageName = "com.google.android.gm";
openApp(context, appName, packageName);

public static void openApp(Context context, String appName, String packageName) {
    if (isAppInstalled(context, packageName))
        if (isAppEnabled(context, packageName))
            context.startActivity(context.getPackageManager().getLaunchIntentForPackage(packageName));
        else Toast.makeText(context, appName + " app is not enabled.", Toast.LENGTH_SHORT).show();
    else Toast.makeText(context, appName + " app is not installed.", Toast.LENGTH_SHORT).show();
}

private static boolean isAppInstalled(Context context, String packageName) {
    PackageManager pm = context.getPackageManager();
    try {
        pm.getPackageInfo(packageName, PackageManager.GET_ACTIVITIES);
        return true;
    } catch (PackageManager.NameNotFoundException ignored) {
    }
    return false;
}

private static boolean isAppEnabled(Context context, String packageName) {
    boolean appStatus = false;
    try {
        ApplicationInfo ai = context.getPackageManager().getApplicationInfo(packageName, 0);
        if (ai != null) {
            appStatus = ai.enabled;
        }
    } catch (PackageManager.NameNotFoundException e) {
        e.printStackTrace();
    }
    return appStatus;
}

我找到了解决办法。在应用程序的清单文件中，我找到了包的名称:com.package.address和我想启动的主活动的名称:MainActivity 下面的代码启动这个应用程序:

Intent intent = new Intent(Intent.ACTION_MAIN);
intent.setComponent(new ComponentName("com.package.address","com.package.address.MainActivity"));
startActivity(intent);

传递包名和你想要显示的消息，如果包没有安装;-)

void openApp(String appPackageName,String message){
    Intent launchIntent = getPackageManager().getLaunchIntentForPackage(appPackageName);
    if (launchIntent != null) {
        startActivity(launchIntent);
    } else {
        Toast.makeText(MainActivity.this, message, Toast.LENGTH_LONG).show();
        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://play.google.com/store/apps/details?id=" + appPackageName)));
    }
}

我知道这个问题已经得到了回答，但以下是我如何实现类似的东西:

Intent intent = getPackageManager().getLaunchIntentForPackage("com.package.name");
if (intent != null) {
    // We found the activity now start the activity
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    startActivity(intent);
} else {
    // Bring user to the market or let them choose an app?
    intent = new Intent(Intent.ACTION_VIEW);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setData(Uri.parse("market://details?id=" + "com.package.name"));
    startActivity(intent);
}

更好的方法是:

public void startNewActivity(Context context, String packageName) {
    Intent intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
    if (intent != null) {
        // We found the activity now start the activity
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    } else {
        // Bring user to the market or let them choose an app?
        intent = new Intent(Intent.ACTION_VIEW);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setData(Uri.parse("market://details?id=" + packageName));
        context.startActivity(intent);
    }
}

删除重复代码:

public void startNewActivity(Context context, String packageName) {
    Intent intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
    if (intent == null) {
        // Bring user to the market or let them choose an app?
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setData(Uri.parse("market://details?id=" + packageName));
    }
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(intent);
}

根据评论进行编辑

在某些版本中(如注释中建议的那样)，抛出的异常可能不同。

因此，下面的解决方案稍作修改

Intent launchIntent = null;
try{
   launchIntent = getPackageManager().getLaunchIntentForPackage("applicationId");
} catch (Exception ignored) {}

if(launchIntent == null){
    startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri.parse("https://play.google.com/store/apps/details?id=" + "applicationId")));
} else {
    startActivity(launchIntent);
}

原来的答案

虽然回答得很好，有一个相当简单的实现来处理如果应用程序没有安装。我这样做

try{
    startActivity(getPackageManager().getLaunchIntentForPackage("applicationId"));
} catch (PackageManager.NameNotFoundException e) {
    startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri.parse("https://play.google.com/store/apps/details?id=" + "applicationId")));
}

将“applicationId”替换为要打开的包，如com.google。地图等。

检查应用程序，避免任何崩溃。如果应用程序在手机中存在，那么它将被启动，否则它将在谷歌Play中搜索。如果手机没有安装谷歌Play app，手机会通过浏览器在谷歌Play Store中搜索:

public void onLunchAnotherApp() {
    final String appPackageName = getApplicationContext().getPackageName();

    Intent intent = getPackageManager().getLaunchIntentForPackage(appPackageName);
    if (intent != null) {
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);
    } else {
        onGoToAnotherInAppStore(intent, appPackageName);
    }
}

public void onGoToAnotherInAppStore(Intent intent, String appPackageName) {
    try {
        intent = new Intent(Intent.ACTION_VIEW);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setData(Uri.parse("market://details?id=" + appPackageName));
        startActivity(intent);
    } catch (android.content.ActivityNotFoundException anfe) {
        intent = new Intent(Intent.ACTION_VIEW);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setData(Uri.parse("http://play.google.com/store/apps/details?id=" + appPackageName));
        startActivity(intent);
    }
}