通过百度地图API将百度坐标转换成GPS经纬度

百度地图API链接：http://developer.baidu.com/map/index.php?title=webapi/guide/changeposition

百度地图API中，有GPS坐标转百度坐标的功能
http://dev.baidu.com/wiki/static/map/API/examples/?v=1.2&0_6#0&6

http接口是：http://api.map.baidu.com/ag/coord/convert?from=0&to=4&x=116.397428&y=39.90923&callback=BMap.Convertor.cbk_7594
返回结果坐标是通过base64加密的。
这个转换算法百度是不会公开的，而且百度也没有提供百度坐标转成GPS坐标功能，这里我用了取巧的办法。

百度坐标和GPS坐标转换在很近的距离时偏差非常接近。
假设你有百度坐标：x1=116.397428，y1=39.90923
把这个坐标当成GPS坐标，通过接口获得他的百度坐标：x2=116.41004950566，y2=39.916979519873

通过计算就可以得到GPS的坐标：
x = 2*x1-x2，y = 2*y1-y2
x=116.38480649434001
y=39.901480480127

在http://dev.baidu.com/wiki/static/map/API/examples/?v=1.2&0_6#0&6 将此坐标输入GPS数据项中得到的结果是：116.39743826208,39.909194650838

实现的java代码如下：

package com.dataprocess;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CopyOfTest {
public static void main(String args[]){
String params =
"coords=114.21892734521,29.575429778924&from=1&to=5&ak=ZQU8ZGeBf95nN8wY1cNL13NP&output=json";

String s=CopyOfTest.sendGet("http://api.map.baidu.com/geoconv/v1/?", params);
String[] s1 = s.split("\\[");
String[] s2 = s1[1].split(",");
String regEx ="[^0-9.\\+\\-\\s]";
Pattern p = Pattern.compile(regEx);
Matcher m1 = p.matcher(s2[0]);
Matcher m2 = p.matcher(s2[1]);
String[] arrs1=m1.replaceAll("").trim().split("\\s");
String[] arrs2=m2.replaceAll("").trim().split("\\s");
System.out.println(s1[1]);
System.out.println(arrs1[0]+" "+arrs2[0]);

}
public static String sendGet(String url, String param) {
String result = "";
BufferedReader in = null;
try {
String urlNameString = url  + param;
URL realUrl = new URL(urlNameString);
// 打开和URL之间的连接
URLConnection connection = realUrl.openConnection();
// 设置通用的请求属性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 建立实际的连接
connection.connect();
// 获取所有响应头字段
Map<String, List<String>> map = connection.getHeaderFields();
// 遍历所有的响应头字段
//            for (String key : map.keySet()) {
//                System.out.println(key + "--->" + map.get(key));
//            }
// 定义 BufferedReader输入流来读取URL的响应
in = new BufferedReader(new InputStreamReader(
connection.getInputStream(),"utf-8"));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送GET请求出现异常！" + e);
e.printStackTrace();
}
// 使用finally块来关闭输入流
finally {
try {
if (in != null) {
in.close();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
return result;
}

/**
* 向指定 URL 发送POST方法的请求
*
* @param url
*            发送请求的 URL
* @param param
*            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return 所代表远程资源的响应结果
*/
public static String sendPost(String url, String param) {
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// 打开和URL之间的连接
URLConnection conn = realUrl.openConnection();
// 设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
// 获取URLConnection对象对应的输出流
out = new PrintWriter(conn.getOutputStream());
// 发送请求参数
out.print(param);
// flush输出流的缓冲
out.flush();
// 定义BufferedReader输入流来读取URL的响应
in = new BufferedReader(
new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送 POST 请求出现异常！"+e);
e.printStackTrace();
}
//使用finally块来关闭输出流、输入流
finally{
try{
if(out!=null){
out.close();
}
if(in!=null){
in.close();
}
}
catch(IOException ex){
ex.printStackTrace();
}
}
return result;
}

}

同时实现读取文本中的百度经纬度坐标实现批量处理并生成gpx格式文档（可上传到openstreetmap形成轨迹）代码如下：

package com.dataprocess;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CopyOfGenerateGpx {
public void generate(){
String fileNames[]={"LocationData_2015-09-15",
"LocationData_2015-09-16"
};
int n = fileNames.length;
for(String fileName: fileNames){
//输入文件
File filein = new File("H:\\项目数据\\测试\\"+fileName+".txt");
//输出文件
File fileout = new File("H:\\项目数据\\测试\\gpx\\"+fileName+".gpx");
//输出json文件
File jsonfile = new File("H:\\项目数据\\测试\\json\\JSON_"+fileName+".json");
try {
//输入流
FileInputStream fis = new FileInputStream(filein);
InputStreamReader isr = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(isr);
//输出流
FileOutputStream fos = new FileOutputStream(fileout);
OutputStreamWriter osw = new OutputStreamWriter(fos);
BufferedWriter bw = new BufferedWriter(osw);
//json输出流
FileOutputStream fos1 = new FileOutputStream(jsonfile);
OutputStreamWriter osw1 = new OutputStreamWriter(fos1);
BufferedWriter bw1 = new BufferedWriter(osw1);
bw1.write("[\r\n");
bw.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n");
bw.write("<gpx version=\"1.1\" creator=\"OSMTrack\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns=\"http://www.topografix.com/GPX/1/1\""
+ " xsi:schemaLocation=\"http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd\">\r\n"); bw.write("<trk>\r\n<trkseg>\r\n");
String line = null;
String regEx ="[^0-9.\\+\\-\\s]";
Pattern p = Pattern.compile(regEx);
while((line=br.readLine())!=null){
Matcher m = p.matcher(line);
String[] arrs=m.replaceAll("").trim().split("\\s");
String lonbd = arrs[2];
String latbd = arrs[3];
String params =
"coords="
+ lonbd+","+latbd
+ "&from=1&to=5&ak=ZQU8ZGeBf95nN8wY1cNL13NP&output=json";
String s=sendGet("http://api.map.baidu.com/geoconv/v1/?", params);
String[] s1 = s.split("\\[");
String[] s2 = s1[1].split(",");
Matcher m1 = p.matcher(s2[0]);
Matcher m2 = p.matcher(s2[1]);
String[] arrs1=m1.replaceAll("").trim().split("\\s");
String[] arrs2=m2.replaceAll("").trim().split("\\s");
System.out.println(s1[1]);
System.out.println(arrs1[0]+" "+arrs2[0]);
double lon = 2*Double.parseDouble(lonbd)-Double.parseDouble(arrs1[0]);
double lat = 2*Double.parseDouble(latbd)-Double.parseDouble(arrs2[0]);
String str = "<trkpt lat=\""+lat+"\" lon=\""+lon+"\"><ele>61.3</ele><time>2015-09-05T14:12:20Z</time></trkpt>";
bw.write(str+"\r\n");
String str1 = "{"
+"\"longitude\": "+lon
+",\"latitude\": "+lat
+"},\r\n";
bw1.write(str1);
System.out.println(str);
}
bw.write("</trkseg>\r\n</trk>\r\n</gpx>\r\n");
bw.flush();
bw1.write("]\r\n");
bw1.flush();
br.close();
fis.close();
bw.close();
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public static String sendGet(String url, String param) {
String result = "";
BufferedReader in = null;
try {
String urlNameString = url  + param;
URL realUrl = new URL(urlNameString);
// 打开和URL之间的连接
URLConnection connection = realUrl.openConnection();
// 设置通用的请求属性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 建立实际的连接
connection.connect();
// 获取所有响应头字段
Map<String, List<String>> map = connection.getHeaderFields();
// 遍历所有的响应头字段
//            for (String key : map.keySet()) {
//                System.out.println(key + "--->" + map.get(key));
//            }
// 定义 BufferedReader输入流来读取URL的响应
in = new BufferedReader(new InputStreamReader(
connection.getInputStream(),"utf-8"));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送GET请求出现异常！" + e);
e.printStackTrace();
}
// 使用finally块来关闭输入流
finally {
try {
if (in != null) {
in.close();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
return result;
}

public static void main(String[] args){
CopyOfGenerateGpx g = new CopyOfGenerateGpx();
g.generate();
}
}