一般使用setType()方法来实现文件过滤，如：只显示PDF文件：

     int requestCode = 100;
     Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
     intent.setType("application/pdf");
     intent.addCategory(Intent.CATEGORY_OPENABLE);
     startActivityForResult(intent, requestCode); 

但如果要指定多种类型呢，同时要指定pdf,excel,word,ppt这些类型的文件，那要怎样设置呢？

指定多种类型文件

在网上查了，有些答案是

错误方式1——setType中进行拼接：

intent.setType(“video/*;image/*”);//同时选择视频和图片

错误方式2——调用多次setType：

intent.setType("video/*");
intent.setType("image/*");

这两种方式都是错误的
我们看下源码

/**
     * Set an explicit MIME data type.
     *
     * <p>This is used to create intents that only specify a type and not data,
     * for example to indicate the type of data to return.
     *
     * <p>This method automatically clears any data that was
     * previously set (for example by {@link #setData}).
     *
     * <p><em>Note: MIME type matching in the Android framework is
     * case-sensitive, unlike formal RFC MIME types.  As a result,
     * you should always write your MIME types with lower case letters,
     * or use {@link #normalizeMimeType} or {@link #setTypeAndNormalize}
     * to ensure that it is converted to lower case.</em>
     *
     * @param type The MIME type of the data being handled by this intent.
     *
     * @return Returns the same Intent object, for chaining multiple calls
     * into a single statement.
     *
     * @see #getType
     * @see #setTypeAndNormalize
     * @see #setDataAndType
     * @see #normalizeMimeType
     */
    public Intent setType(String type) {
        mData = null;
        mType = type;
        return this;
    }

我们可以看到，setType每次都是重新赋值，没有添加到list和数组中，因此这两种方式是实现不了指定多种类型文件的。
既然这种方式实现不了，那么Intent会不会提供字段以便我们传递过滤数据，我们通过官方文档及源码，发现Intent提供了EXTRA_MIME_TYPES这个字段来传递，而且是数组类型：

/**
     * Extra used to communicate a set of acceptable MIME types. The type of the
     * extra is {@code String[]}. Values may be a combination of concrete MIME
     * types (such as "image/png") and/or partial MIME types (such as
     * "audio/*").
     *
     * @see #ACTION_GET_CONTENT
     * @see #ACTION_OPEN_DOCUMENT
     */
    public static final String EXTRA_MIME_TYPES = "android.intent.extra.MIME_TYPES";

因此结果就简单了,我们要指定ppt,word,excel,pdf类型的文件，代码如下

public static void openDirChooseFile(Activity activity, int requestCode, String[] mimeTypes) {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        if (mimeTypes != null) {
            intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
        }
        intent.setType("*/*");
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        // intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);//多选
        activity.startActivityForResult(intent, requestCode);
    }
 public static void chooseFile(Activity activity, int requestCode) {
        String[] mimeTypes = {MimeType.DOC, MimeType.DOCX, MimeType.PDF, MimeType.PPT, MimeType.PPTX, MimeType.XLS, MimeType.XLSX};
        FileUtil.openDirChooseFile(activity, requestCode, mimeTypes);
    }

MimeType文件

public class MimeType {
    public static final String DOC = "application/msword";
    public static final String DOCX = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
    public static final String XLS = "application/vnd.ms-excel application/x-excel";
    public static final String XLSX = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
    public static final String PPT = "application/vnd.ms-powerpoint";
    public static final String PPTX = "application/vnd.openxmlformats-officedocument.presentationml.presentation";
    public static final String PDF = "application/pdf";
}

Intent指定多种类型的文件，正确的做法，是通过Intent.EXTRA_MIME_TYPES传递Mime类型数组实现

 intent.setType("*/*");
 intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);

MimeType 文件列表参考

 1. Mozilla MDN Web Docs: https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types

2. AOSP MediaFle:  

frameworks/base/media/java/android/media/MediaFile.java

    public static String getMimeTypeForFile(String path) {
        MediaFileType mediaFileType = getFileType(path);
        return (mediaFileType == null ? null : mediaFileType.mimeType);
    }

    static {
        /// M: Add more audio file types to maps. {@
        addFileType("3GP", FILE_TYPE_3GPP3, "audio/3gpp");
        addFileType("3GA", FILE_TYPE_3GA, "audio/3gpp");
        addFileType("MOV", FILE_TYPE_QUICKTIME_AUDIO, "audio/quicktime");
        addFileType("QT", FILE_TYPE_QUICKTIME_AUDIO, "audio/quicktime");
        /// Add to support Apple Lossless Codec(audio/alac)
        addFileType("CAF", FILE_TYPE_CAF, "audio/alac");
        /// Add to support PCM(audio/wav)
        addFileType("WAV", FILE_TYPE_WAV, "audio/wav", MtpConstants.FORMAT_WAV);
        addFileType("OGG", FILE_TYPE_OGG, "audio/vorbis", MtpConstants.FORMAT_OGG);
        addFileType("OGG", FILE_TYPE_OGG, "audio/webm", MtpConstants.FORMAT_OGG);
        /// Add to support MP2, first add video/mp2p, so that use MP2 can return as audio type
        addFileType("MP2", FILE_TYPE_MP2PS, "video/mp2p");
        addFileType("MP2", FILE_TYPE_MP2, "audio/mpeg");
        /// Add to support Monkey's Audio APE(audio/ape)
        if (SystemProperties.getBoolean("ro.mtk_audio_ape_support", false)) {
            addFileType("APE", FILE_TYPE_APE, "audio/ape");
        }
        /// Add to support OMA DRM audio type DCF
        if (SystemProperties.getBoolean("ro.mtk_oma_drm_support", false)) {
            addFileType("DCF", FILE_TYPE_MP3, "audio/mpeg");
        }
        /// @}

        addFileType("MP3", FILE_TYPE_MP3, "audio/mpeg", MtpConstants.FORMAT_MP3);
        addFileType("MPGA", FILE_TYPE_MP3, "audio/mpeg", MtpConstants.FORMAT_MP3);
        addFileType("M4A", FILE_TYPE_M4A, "audio/mp4", MtpConstants.FORMAT_MPEG);
        addFileType("WAV", FILE_TYPE_WAV, "audio/x-wav", MtpConstants.FORMAT_WAV);
        addFileType("AMR", FILE_TYPE_AMR, "audio/amr");
        addFileType("AWB", FILE_TYPE_AWB, "audio/amr-wb");
        if (isWMAEnabled()) {
            addFileType("WMA", FILE_TYPE_WMA, "audio/x-ms-wma", MtpConstants.FORMAT_WMA);
        }
        addFileType("OGG", FILE_TYPE_OGG, "audio/ogg", MtpConstants.FORMAT_OGG);
        addFileType("OGG", FILE_TYPE_OGG, "application/ogg", MtpConstants.FORMAT_OGG);
        addFileType("OGA", FILE_TYPE_OGG, "application/ogg", MtpConstants.FORMAT_OGG);
        addFileType("AAC", FILE_TYPE_AAC, "audio/aac", MtpConstants.FORMAT_AAC);
        addFileType("AAC", FILE_TYPE_AAC, "audio/aac-adts", MtpConstants.FORMAT_AAC);
        addFileType("MKA", FILE_TYPE_MKA, "audio/x-matroska");

        addFileType("MID", FILE_TYPE_MID, "audio/midi");
        addFileType("MIDI", FILE_TYPE_MID, "audio/midi");
        addFileType("XMF", FILE_TYPE_MID, "audio/midi");
        addFileType("RTTTL", FILE_TYPE_MID, "audio/midi");
        addFileType("SMF", FILE_TYPE_SMF, "audio/sp-midi");
        addFileType("IMY", FILE_TYPE_IMY, "audio/imelody");
        addFileType("RTX", FILE_TYPE_MID, "audio/midi");
        addFileType("OTA", FILE_TYPE_MID, "audio/midi");
        addFileType("MXMF", FILE_TYPE_MID, "audio/midi");

        /// M: Add more video file types to maps. {@
        addFileType("MTS", FILE_TYPE_MP2TS, "video/mp2ts");
        addFileType("M2TS", FILE_TYPE_MP2TS, "video/mp2ts");
        addFileType("MOV", FILE_TYPE_QUICKTIME_VIDEO, "video/quicktime");
        addFileType("QT", FILE_TYPE_QUICKTIME_VIDEO, "video/quicktime");
        addFileType("OGV", FILE_TYPE_OGM, "video/ogm");
        addFileType("OGM", FILE_TYPE_OGM, "video/ogm");
        if (SystemProperties.getBoolean("ro.mtk_flv_playback_support", false)) {
            addFileType("FLV", FILE_TYPE_FLV, "video/x-flv");
            addFileType("F4V", FILE_TYPE_FLV, "video/x-flv");
            addFileType("PFV", FILE_TYPE_FLV, "video/x-flv");
            addFileType("FLA", FILE_TYPE_FLA, "audio/x-flv");
        }
        if (SystemProperties.getBoolean("ro.mtk_mtkps_playback_support", false)) {
            addFileType("PS", FILE_TYPE_MP2PS, "video/mp2p");
            /// Only support VOB when mtkps feature option is enabled
            addFileType("VOB", FILE_TYPE_MP2PS, "video/mp2p");
            /// DAT files should not be scanned as mpeg2 PS if PS is not supported.
            addFileType("DAT", FILE_TYPE_MP2PS, "video/mp2p");
        }
        /// @}

        addFileType("MPEG", FILE_TYPE_MP4, "video/mpeg", MtpConstants.FORMAT_MPEG);
        addFileType("MPG", FILE_TYPE_MP4, "video/mpeg", MtpConstants.FORMAT_MPEG);
        addFileType("MP4", FILE_TYPE_MP4, "video/mp4", MtpConstants.FORMAT_MPEG);
        addFileType("M4V", FILE_TYPE_M4V, "video/mp4", MtpConstants.FORMAT_MPEG);
        addFileType("3GP", FILE_TYPE_3GPP, "video/3gpp",  MtpConstants.FORMAT_3GP_CONTAINER);
        addFileType("3GPP", FILE_TYPE_3GPP, "video/3gpp", MtpConstants.FORMAT_3GP_CONTAINER);
        addFileType("3G2", FILE_TYPE_3GPP2, "video/3gpp2", MtpConstants.FORMAT_3GP_CONTAINER);
        addFileType("3GPP2", FILE_TYPE_3GPP2, "video/3gpp2", MtpConstants.FORMAT_3GP_CONTAINER);
        addFileType("MKV", FILE_TYPE_MKV, "video/x-matroska");
        addFileType("WEBM", FILE_TYPE_WEBM, "video/webm");
        addFileType("TS", FILE_TYPE_MP2TS, "video/mp2ts");
        addFileType("AVI", FILE_TYPE_AVI, "video/avi");

        if (isWMVEnabled()) {
            addFileType("WMV", FILE_TYPE_WMV, "video/x-ms-wmv", MtpConstants.FORMAT_WMV);
            addFileType("ASF", FILE_TYPE_ASF, "video/x-ms-asf");
        }

        /// M: Add more image file types to maps. {@
        if (!SystemProperties.getBoolean("ro.mtk_bsp_package", false)) {
            /// Mpo files should not be scanned as images in BSP
            addFileType("MPO", FILE_TYPE_MPO, "image/mpo");
        }
        /// @}

        addFileType("JPG", FILE_TYPE_JPEG, "image/jpeg", MtpConstants.FORMAT_EXIF_JPEG);
        addFileType("JPEG", FILE_TYPE_JPEG, "image/jpeg", MtpConstants.FORMAT_EXIF_JPEG);
        addFileType("GIF", FILE_TYPE_GIF, "image/gif", MtpConstants.FORMAT_GIF);
        addFileType("PNG", FILE_TYPE_PNG, "image/png", MtpConstants.FORMAT_PNG);
        addFileType("BMP", FILE_TYPE_BMP, "image/x-ms-bmp", MtpConstants.FORMAT_BMP);
        addFileType("WBMP", FILE_TYPE_WBMP, "image/vnd.wap.wbmp");
        addFileType("WEBP", FILE_TYPE_WEBP, "image/webp");

        addFileType("M3U", FILE_TYPE_M3U, "audio/x-mpegurl", MtpConstants.FORMAT_M3U_PLAYLIST);
        addFileType("M3U", FILE_TYPE_M3U, "application/x-mpegurl", MtpConstants.FORMAT_M3U_PLAYLIST);
        addFileType("PLS", FILE_TYPE_PLS, "audio/x-scpls", MtpConstants.FORMAT_PLS_PLAYLIST);
        addFileType("WPL", FILE_TYPE_WPL, "application/vnd.ms-wpl", MtpConstants.FORMAT_WPL_PLAYLIST);
        addFileType("M3U8", FILE_TYPE_HTTPLIVE, "application/vnd.apple.mpegurl");
        addFileType("M3U8", FILE_TYPE_HTTPLIVE, "audio/mpegurl");
        addFileType("M3U8", FILE_TYPE_HTTPLIVE, "audio/x-mpegurl");

        addFileType("FL", FILE_TYPE_FL, "application/x-android-drm-fl");

        addFileType("TXT", FILE_TYPE_TEXT, "text/plain", MtpConstants.FORMAT_TEXT);
        addFileType("HTM", FILE_TYPE_HTML, "text/html", MtpConstants.FORMAT_HTML);
        addFileType("HTML", FILE_TYPE_HTML, "text/html", MtpConstants.FORMAT_HTML);
        addFileType("PDF", FILE_TYPE_PDF, "application/pdf");
        addFileType("DOC", FILE_TYPE_MS_WORD, "application/msword", MtpConstants.FORMAT_MS_WORD_DOCUMENT);
        addFileType("XLS", FILE_TYPE_MS_EXCEL, "application/vnd.ms-excel", MtpConstants.FORMAT_MS_EXCEL_SPREADSHEET);
        addFileType("PPT", FILE_TYPE_MS_POWERPOINT, "application/vnd.ms-powerpoint", MtpConstants.FORMAT_MS_POWERPOINT_PRESENTATION);
        addFileType("FLAC", FILE_TYPE_FLAC, "audio/flac", MtpConstants.FORMAT_FLAC);
        addFileType("ZIP", FILE_TYPE_ZIP, "application/zip");
        addFileType("MPG", FILE_TYPE_MP2PS, "video/mp2p");
        addFileType("MPEG", FILE_TYPE_MP2PS, "video/mp2p");

        /// M: Add more Other popular file types to maps. {@
        addFileType("ICS", FILE_TYPE_ICS, "text/calendar");
        addFileType("ICZ", FILE_TYPE_ICZ, "text/calendar");
        addFileType("VCF", FILE_TYPE_VCF, "text/x-vcard");
        addFileType("VCS", FILE_TYPE_VCS, "text/x-vcalendar");
        addFileType("APK", FILE_TYPE_APK, "application/vnd.android.package-archive");
        addFileType("DOCX", FILE_TYPE_MS_WORD, "application/vnd.openxmlformats-officedocument.wordprocessingml.document");
        addFileType("DOTX", FILE_TYPE_MS_WORD, "application/vnd.openxmlformats-officedocument.wordprocessingml.template");
        addFileType("XLSX", FILE_TYPE_MS_EXCEL, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        addFileType("XLTX", FILE_TYPE_MS_EXCEL, "application/vnd.openxmlformats-officedocument.spreadsheetml.template");
        addFileType("PPTX", FILE_TYPE_MS_POWERPOINT, "application/vnd.openxmlformats-officedocument.presentationml.presentation");
        addFileType("POTX", FILE_TYPE_MS_POWERPOINT, "application/vnd.openxmlformats-officedocument.presentationml.template");
        addFileType("PPSX", FILE_TYPE_MS_POWERPOINT, "application/vnd.openxmlformats-officedocument.presentationml.slideshow");
        /// @}
    }

根据不同的MIME类型，显示不同的图标：

    /**
     * This method gets the drawable id based on the mimetype
     *
     * @param mimeType the mimeType of a file/folder
     * @return the drawable icon id based on the mimetype
     */
    public static int getDrawableId(Context context, String mimeType) {
        if (TextUtils.isEmpty(mimeType)) {
            return R.drawable.fm_unknown;
        } else if (mimeType.startsWith("application/vnd.android.package-archive")) {
            return R.drawable.fm_apk;
        } else if (mimeType.startsWith("application/zip")) {
            return R.drawable.fm_zip;
        } else if (mimeType.startsWith("application/ogg")) {
            return R.drawable.fm_audio;
        } else if (mimeType.startsWith("audio/")) {
            return R.drawable.fm_audio;
        } else if (mimeType.startsWith("image/")) {
            return R.drawable.fm_picture;
        } else if (mimeType.startsWith("text/")) {
            return R.drawable.fm_txt;
        } else if (mimeType.startsWith("video/")) {
            return R.drawable.fm_video;
        }
        return getCustomDrawableId(context, mimeType);
    }

参考链接

1. Android之Intent筛选多种类型文件

2. Android MediaFile对常见MIME的定义

 android: 通过Intent筛选多种类型文件 - 夜行过客 - 博客园 (cnblogs.com)