获取文件类型并调用系统应用打开相应文件

import android.content.Context;
import android.content.Intent;
import android.net.Uri;

import androidx.core.content.FileProvider;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;

public class FileUtil {

    /**
     * 获取文件类型
     * （获取图片jpg、png等格式、文件word、xml等格式等）
     * @param filePath
     * @return
     */
    public static String getFileType(String filePath) {
        HashMap<String, String> mFileTypes = new HashMap<String, String>();
        mFileTypes.put("FFD8FF", "jpg");
        mFileTypes.put("89504E47", "png");
        mFileTypes.put("89504E", "png");
        mFileTypes.put("47494638", "gif");
        mFileTypes.put("49492A00", "tif");
        mFileTypes.put("424D", "bmp");
        mFileTypes.put("41433130", "dwg"); //CAD
        mFileTypes.put("38425053", "psd");
        mFileTypes.put("7B5C727466", "rtf"); //日记本
        mFileTypes.put("3C3F786D6C", "xml");
        mFileTypes.put("68746D6C3E", "html");
        mFileTypes.put("44656C69766572792D646174653A", "eml"); //邮件
        mFileTypes.put("D0CF11E0", "doc");
        mFileTypes.put("5374616E64617264204A", "mdb");
        mFileTypes.put("252150532D41646F6265", "ps");
        mFileTypes.put("255044462D312E", "pdf");
        mFileTypes.put("504B0304", "zip");
        mFileTypes.put("504B03", "apk");
        mFileTypes.put("52617221", "rar");
        mFileTypes.put("57415645", "wav");
        mFileTypes.put("41564920", "avi");
        mFileTypes.put("2E524D46", "rm");
        mFileTypes.put("000001BA", "mpg");
        mFileTypes.put("000001B3", "mpg");
        mFileTypes.put("6D6F6F76", "mov");
        mFileTypes.put("3026B2758E66CF11", "asf");
        mFileTypes.put("4D546864", "mid");
        mFileTypes.put("1F8B08", "gz");
        mFileTypes.put("000000", "mp4");
        if (getFileHeader(filePath) != null) {
            if(mFileTypes.get(getFileHeader(filePath))!=null){
               return mFileTypes.get(getFileHeader(filePath));
            }else{
               return "unknown";
           }
            return mFileTypes.get(getFileHeader(filePath));
        } else {
            return "";
        }
    }

    /**
     * 获取文件头信息
     *
     * @param filePath
     * @return
     */
    public static String getFileHeader(String filePath) {
        FileInputStream is = null;
        String value = null;
        try {
            is = new FileInputStream(filePath);
            byte[] b = new byte[3];
            is.read(b, 0, b.length);
            value = bytesToHexString(b);
        } catch (Exception e) {
        } finally {
            if (null != is) {
                try {
                    is.close();
                } catch (IOException e) {
                }
            }
        }
        return value;
    }

    /**
     * 将byte字节转换为十六进制字符串
     *
     * @param src
     * @return
     */
    private static String bytesToHexString(byte[] src) {
        StringBuilder builder = new StringBuilder();
        if (src == null || src.length <= 0) {
            return null;
        }
        String hv;
        for (int i = 0; i < src.length; i++) {
            hv = Integer.toHexString(src[i] & 0xFF).toUpperCase();
            if (hv.length() < 2) {
                builder.append(0);
            }
            builder.append(hv);
        }
        return builder.toString();
    }

    public static void openFile(Context context, String filePath) {
        Intent intent = new Intent(Intent.ACTION_VIEW);
        File file = new File(filePath);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        //android 7.0及以上记得添加
        Uri contentUri = FileProvider.getUriForFile(context, context.getPackageName() + ".fileProvider", file);
        switch (getFileType(filePath)) {
            case "mp4":
                //已测试，可行
                intent.setDataAndType(contentUri, "video/*");
                break;
            case "jpg":
            case "png":
            case "gif":
                intent.setDataAndType(contentUri, "image/*");
                break;
            case "pdf":
                intent.setDataAndType(contentUri, "application/pdf");
                break;
            case "apk":
                //已测试，可行
                intent.setDataAndType(contentUri, "application/vnd.android.package-archive");
                break;
            case "unknown":
            default:
                intent.setDataAndType(contentUri, "*/*");
                break;
        }
        //如果判断包含文件类型会调用系统默认应用，不包含，弹出选择弹窗自己选择
        //注意：不要使用startActivity(intent)，测试过很多情况下跳转失败;
        context.startActivity(Intent.createChooser(intent, "Select browse tool"));
    }
}

附，相应文件类型跳转type

        //默认跳转
        Intent intent = new Intent(Intent.ACTION_VIEW);
        Uri uri = Uri.fromFile(file);
        intent.addCategory(Intent.CATEGORY_DEFAULT);
        //打开图片文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"image/*");
        //打开PDF文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/pdf");
        //打开文本文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"text/plain");
        //打开音频文件
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        intent.putExtra("oneshot",0);
        intent.putExtra("configchange",0);
        intent.setDataAndType(uri,"audio/*");
        //打开视频文件
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        intent.putExtra("oneshot",0);
        intent.putExtra("configchange",0);
        intent.setDataAndType(uri,"video/*");
        //打开CHM文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/x-chm");
        //打开apk文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/vnd.android.package-archive");
        //打开PPT文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/vnd.ms-powerpoint");
        //打开Excel文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/vnd.ms-excel");
        //打开Word文件
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setDataAndType(uri,"application/msword");