开发过程中，遇见 android.util.AndroidRuntimeException Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want？ 这个崩溃信息! 在此记录一下解决方法：

原因：Context中有一个startActivity方法，Activity继承自Context，重载了startActivity方法。如果使用 Activity的startActivity方法，不会有任何限制，而如果使用Context的startActivity方法的话，就需要开启一个新的task，遇到上面那个异常的，都是因为使用了Context的startActivity方法。解决办法是，加一个flag。

intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

未加之前的代码：

public static void installApk(Context context, File file){
        Intent intent = new Intent(Intent.ACTION_VIEW);
        //判断是否是AndroidN以及更高的版本
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
            Uri contentUri = FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID + ".fileProvider", file);
            intent.setDataAndType(contentUri, "application/vnd.android.package-archive");
        } else {
            intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        }
        context.startActivity(intent);
    }

加过之后的代码：

public static void installApk(Context context, File file){
        Intent intent = new Intent(Intent.ACTION_VIEW);
        //判断是否是AndroidN以及更高的版本
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_GRANT_READ_URI_PERMISSION);
            Uri contentUri = FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID + ".fileProvider", file);
            intent.setDataAndType(contentUri, "application/vnd.android.package-archive");
        } else {
            intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        }
        context.startActivity(intent);
    }

附加一个MIME类型对照表：

      final String[][] MIME_MapTable={ 
        //{后缀名，MIME类型} 
        {".3gp",    "video/3gpp"}, 
        {".apk",    "application/vnd.android.package-archive"}, 
        {".asf",    "video/x-ms-asf"}, 
        {".avi",    "video/x-msvideo"}, 
        {".bin",    "application/octet-stream"}, 
        {".bmp",    "image/bmp"}, 
        {".c",  "text/plain"}, 
        {".class",  "application/octet-stream"}, 
        {".conf",   "text/plain"}, 
        {".cpp",    "text/plain"}, 
        {".doc",    "application/msword"}, 
        {".docx",   "application/vnd.openxmlformats-officedocument.wordprocessingml.document"}, 
        {".xls",    "application/vnd.ms-excel"},  
        {".xlsx",   "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"}, 
        {".exe",    "application/octet-stream"}, 
        {".gif",    "image/gif"}, 
        {".gtar",   "application/x-gtar"}, 
        {".gz", "application/x-gzip"}, 
        {".h",  "text/plain"}, 
        {".htm",    "text/html"}, 
        {".html",   "text/html"}, 
        {".jar",    "application/java-archive"}, 
        {".java",   "text/plain"}, 
        {".jpeg",   "image/jpeg"}, 
        {".jpg",    "image/jpeg"}, 
        {".js", "application/x-javascript"}, 
        {".log",    "text/plain"}, 
        {".m3u",    "audio/x-mpegurl"}, 
        {".m4a",    "audio/mp4a-latm"}, 
        {".m4b",    "audio/mp4a-latm"}, 
        {".m4p",    "audio/mp4a-latm"}, 
        {".m4u",    "video/vnd.mpegurl"}, 
        {".m4v",    "video/x-m4v"},  
        {".mov",    "video/quicktime"}, 
        {".mp2",    "audio/x-mpeg"}, 
        {".mp3",    "audio/x-mpeg"}, 
        {".mp4",    "video/mp4"}, 
        {".mpc",    "application/vnd.mpohun.certificate"},        
        {".mpe",    "video/mpeg"},   
        {".mpeg",   "video/mpeg"},   
        {".mpg",    "video/mpeg"},   
        {".mpg4",   "video/mp4"},    
        {".mpga",   "audio/mpeg"}, 
        {".msg",    "application/vnd.ms-outlook"}, 
        {".ogg",    "audio/ogg"}, 
        {".pdf",    "application/pdf"}, 
        {".png",    "image/png"}, 
        {".pps",    "application/vnd.ms-powerpoint"}, 
        {".ppt",    "application/vnd.ms-powerpoint"}, 
        {".pptx",   "application/vnd.openxmlformats-officedocument.presentationml.presentation"}, 
        {".prop",   "text/plain"}, 
        {".rc", "text/plain"}, 
        {".rmvb",   "audio/x-pn-realaudio"}, 
        {".rtf",    "application/rtf"}, 
        {".sh", "text/plain"}, 
        {".tar",    "application/x-tar"},    
        {".tgz",    "application/x-compressed"},  
        {".txt",    "text/plain"}, 
        {".wav",    "audio/x-wav"}, 
        {".wma",    "audio/x-ms-wma"}, 
        {".wmv",    "audio/x-ms-wmv"}, 
        {".wps",    "application/vnd.ms-works"}, 
        {".xml",    "text/plain"}, 
        {".z",  "application/x-compress"}, 
        {".zip",    "application/x-zip-compressed"}, 
        {"",        "*/*"}