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android实现将位置信息写入JPEG图片文件

  • 时间:2020-08-12 03:49 编辑: 来源: 阅读:
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摘要:android实现将位置信息写入JPEG图片文件
通过ExifInterface可以将拍照时的一些属性信息写入图片文件里,其中包括经纬度信息。本文介绍一种将经纬度坐标写入JPEG图片文件的方法! [b]核心代码[/b]
/**
* 浮点型经纬度值转成度分秒格式
* 
* @param coord
* @return
*/
 public String decimalToDMS(double coord) {
 String output, degrees, minutes, seconds;

// gets the modulus the coordinate divided by one (MOD1).
// in other words gets all the numbers after the decimal point.
// e.g. mod := -79.982195 % 1 == 0.982195
//
// next get the integer part of the coord. On other words the whole
// number part.
// e.g. intPart := -79

 double mod = coord % 1;
 int intPart = (int) coord;

// set degrees to the value of intPart
// e.g. degrees := "-79"

 degrees = String.valueOf(intPart);

// next times the MOD1 of degrees by 60 so we can find the integer part
// for minutes.
// get the MOD1 of the new coord to find the numbers after the decimal
// point.
// e.g. coord := 0.982195 * 60 == 58.9317
// mod := 58.9317 % 1 == 0.9317
//
// next get the value of the integer part of the coord.
// e.g. intPart := 58

 coord = mod * 60;
 mod = coord % 1;
 intPart = (int) coord;
 if (intPart < 0) {
  // Convert number to positive if it's negative.
  intPart *= -1;
}

// set minutes to the value of intPart.
// e.g. minutes = "58"
 minutes = String.valueOf(intPart);

// do the same again for minutes
// e.g. coord := 0.9317 * 60 == 55.902
// e.g. intPart := 55
 coord = mod * 60;
 intPart = (int) coord;
 if (intPart < 0) {
  // Convert number to positive if it's negative.
  intPart *= -1;
 }

// set seconds to the value of intPart.
// e.g. seconds = "55"
 seconds = String.valueOf(intPart);

// I used this format for android but you can change it
// to return in whatever format you like
// e.g. output = "-79/1,58/1,56/1"
 output = degrees + "/1," + minutes + "/1," + seconds + "/1";

// Standard output of D°M′S″
// output = degrees + "°" + minutes + "'" + seconds + "\"";

 return output;
 }

/**
* 将经纬度信息写入JPEG图片文件里
* 
* @param picPath
*      JPEG图片文件路径
* @param dLat
*      纬度
* @param dLon
*      经度
*/
 public void writeLatLonIntoJpeg(String picPath, double dLat, double dLon) {
 File file = new File(picPath);
 if (file.exists()) {
 try {
 ExifInterface exif = new ExifInterface(picPath);
 String tagLat = exif
 .getAttribute(ExifInterface.TAG_GPS_LATITUDE);
 String tagLon = exif
 .getAttribute(ExifInterface.TAG_GPS_LONGITUDE);
 if (tagLat == null && tagLon == null) // 无经纬度信息
{
 exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE,
 decimalToDMS(dLat));
 exif.setAttribute(ExifInterface.TAG_GPS_LATITUDE_REF,
 dLat > 0 ? "N" : "S"); // 区分南北半球
 exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE,
 decimalToDMS(dLon));
 exif.setAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF,
 dLon > 0 ? "E" : "W"); // 区分东经西经

 exif.saveAttributes();
}
 } catch (Exception e) {

 }
}
 }
[b]测试代码[/b]
String strImgPath = getImageCachePath() + File.separator + "1.jpg";

ExifInterface eif = new ExifInterface(strImgPath);
String lat = eif.getAttribute(ExifInterface.TAG_GPS_LATITUDE);
String latRef = eif.getAttribute(ExifInterface.TAG_GPS_LATITUDE_REF);
String lon = eif.getAttribute(ExifInterface.TAG_GPS_LONGITUDE);
String lonRef = eif.getAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF);

System.out.println("Latitude Ref - " + latRef);
System.out.println("Latitude - " + lat);
System.out.println("Longitude Ref - " + lonRef);
System.out.println("Longitude - " + lon);

if (lat == null && lon == null) // 没有位置信息才写入
{
 writeLatLonIntoJpeg(strImgPath, 39.23456, 116.123456);
}

[b]第一次运行结果[/b]
05-22 17:36:24.566: I/System.out(17966): Latitude Ref - null
05-22 17:36:24.566: I/System.out(17966): Latitude - null
05-22 17:36:24.566: I/System.out(17966): Longitude Ref - null
05-22 17:36:24.566: I/System.out(17966): Longitude - null

原始图片没有位置信息,通过调用writeLatLonIntoJpeg(strImgPath, 39.23456, 116.123456)来模拟写入一个位置。 [b]第二次运行结果[/b]
05-22 17:37:11.446: I/System.out(17966): Latitude Ref - N
05-22 17:37:11.446: I/System.out(17966): Latitude - 39/1,14/1,4/1
05-22 17:37:11.446: I/System.out(17966): Longitude Ref - E
05-22 17:37:11.446: I/System.out(17966): Longitude - 116/1,7/1,24/1

以上这篇android实现将位置信息写入JPEG图片文件就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持编程素材网。
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