百度显示坐标经过了两次加密所以需要转换。

<pre name="code" class="java">package test;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;
import java.text.ParseException;import sun.misc.BASE64Decoder;/*** GPS坐标转百度坐标测试* @author Administrator**/
public class LoctionTest {public static void main(String args[]) throws ParseException {changgeXY("120.11508", "30.279146");}public static String changgeXY(String xx, String yy) {try {Socket s = new Socket("api.map.baidu.com", 80);BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream(), "UTF-8"));OutputStream out = s.getOutputStream();StringBuffer sb = new StringBuffer("GET /ag/coord/convert?from=0&to=4");sb.append("&x=" + xx + "&y=" + yy);sb.append("&callback=BMap.Convertor.cbk_3976 HTTP/1.1\r\n");sb.append("User-Agent: Java/1.6.0_20\r\n");sb.append("Host: api.map.baidu.com:80\r\n");sb.append("Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2\r\n");sb.append("Connection: Close\r\n");sb.append("\r\n");out.write(sb.toString().getBytes());String json = "";String tmp = "";while ((tmp = br.readLine()) != null) {// System.out.println(tmp);json += tmp;}int start = json.indexOf("cbk_3976");int end = json.lastIndexOf("}");if (start != -1 && end != -1&& json.contains("\"x\":\"")) {json = json.substring(start, end);String[] point = json.split(",");String x = point[1].split(":")[1].replace("\"", "");String y = point[2].split(":")[1].replace("\"", "");//System.out.println(new String(decode(x)) + "," + new String(decode(y)));//String result = new String(decode(x)) + "," + new String(decode(y));//System.out.println(result.substring(0, result.indexOf(",")));//System.out.println(result.substring(result.indexOf(",")+1));return (new String(decode(x)) + "," + new String(decode(y)));} else {System.out.println("gps坐标无效！！");}out.close();br.close();} catch (Exception e) {e.printStackTrace();}return null;}/*** 解码* @param str* @return string*/public static byte[] decode(String str) {byte[] bt = null;try {BASE64Decoder decoder = new BASE64Decoder();bt = decoder.decodeBuffer(str);// System.out.println(new String (bt));} catch (IOException e) {e.printStackTrace();}return bt;}}
//===========================================================================================================================================import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.text.ParseException;import net.sf.json.JSONObject;import com.alibaba.fastjson.util.Base64;
/*** goolg坐标转百度坐标* @author Administrator**/
public class GoolgToBaiduTest {
public static void main(String args[]) throws ParseException {String result = GoolgToBaidu("120.11508", "30.279146");JSONObject  dataJson=JSONObject.fromObject(result);String x = String.valueOf(dataJson.get("x"));String y = String.valueOf(dataJson.get("y"));byte[] x1=Base64.decodeFast(x);byte[] y1=Base64.decodeFast(y);double lon = Double.parseDouble(new String(x1));double lat = Double.parseDouble(new String(y1));System.out.println(lon+","+lat);
}
public static  String GoolgToBaidu(String lon, String lat) {
String result = "";String url="http://api.map.baidu.com/ag/coord/convert?from=2&to=4&x="+lon+"&y="+lat;try{//String urlName = url + "?"+param;URL U = new URL(url);URLConnection connection = U.openConnection();connection.connect(); BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));String line;while ((line = in.readLine())!= null){result += line;}in.close();   }catch(Exception e){System.out.println("没有结果！"+e);}return result;
}

百度转GPS简单粗暴的方法：

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