最近公司業務需要外匯轉換，這裡記錄下匯率實時更新的處理方式

1. 申請匯率API介面（這裡用的是聚合資料的API，免費每天呼叫100次）
2. 程式設計用到的語言（網站上有對應的基本測試程式碼）
3. 新建測試專案，匯入所需jar包（Myeclipse）
4. 根據需求更改程式碼
5. 呼叫成功（大功告成）
   程式碼貼出來：

 package com.goldatg.util;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
/**
 * 
 * @專案名稱:@{project_name}
 * @類名稱:@{type_name}
 * @類描述:
 * @建立人:{user}
 * @建立時間:2017-5-24下午4:02:35
 * 
 * @修改人:
 * @修改時間:2017-5-24下午4:02:35
 * @修改備註:
 * @version:
 */
 

public class ExchangeUtil {
    public static final String DEF_CHATSET = "UTF-8";
    public static final int DEF_CONN_TIMEOUT = 30000;
    public static final int DEF_READ_TIMEOUT = 30000;
    public static String userAgent =  "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.66 Safari/537.36"
 
;

    //配置您申請的KEY
    public static final String APPKEY ="*****************";

    //1.常用匯率查詢
    public static void getRequestExchange(){
        String result =null;
        String url ="http://op.juhe.cn/onebox/exchange/query";//請求介面地址
        Map params = new HashMap();//請求引數
            params.put("key",APPKEY);//應用APPKEY(應用詳細頁查詢)
 


        try {
            result =net(url, params, "GET");
            JSONObject object = JSONObject.fromObject(result);
            if(object.getInt("error_code")==0){
                System.out.println(object.get("result"));
            }else{
                System.out.println(object.get("error_code")+":"+object.get("reason"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //2.貨幣列表
    public static String getRequestCurrencyList(){
        String result =null;
        String url ="http://op.juhe.cn/onebox/exchange/list";//請求介面地址
        String currencyList = null;//貨幣列表
        Map params = new HashMap();//請求引數
            params.put("key",APPKEY);//應用APPKEY(應用詳細頁查詢)

        try {
            result =net(url, params, "GET");
            JSONObject object = JSONObject.fromObject(result);
            if(object.getInt("error_code")==0){
                System.out.println(object.get("result"));
                currencyList = object.get("result").toString();
            }else{
                System.out.println(object.get("error_code")+":"+object.get("reason"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return currencyList;
    }

    //3.實時匯率查詢換算
    public static String getRequestConversion(String currency){
        String result =null;
        String url ="http://op.juhe.cn/onebox/exchange/currency";//請求介面地址
        String multiple = null;//轉換後得到的倍數
        Map params = new HashMap();//請求引數
            params.put("from","USD");//轉換匯率前的貨幣程式碼
            params.put("to",currency);//轉換匯率成的貨幣程式碼
            params.put("key",APPKEY);//應用APPKEY(應用詳細頁查詢)

        try {
            result =net(url, params, "GET");
            JSONObject object = JSONObject.fromObject(result);//得到當前返回的結果
            String str = object.get("result").toString();//根據鍵“result”得到值
            JSONArray objArray = JSONArray.fromObject(str);//轉換成JSON陣列物件
            multiple = (String) objArray.getJSONObject(0).get("result");//得到精確值
            if(object.getInt("error_code")==0){
                System.out.println(object.get("result"));
                System.out.println(multiple);
            }else{
                System.out.println(object.get("error_code")+":"+object.get("reason"));

            }
        } catch (Exception e) {
            e.printStackTrace(); 
        }
        return multiple;
    }



    public static void main(String[] args) {

    }

    /**
     *
     * @param strUrl 請求地址
     * @param params 請求引數
     * @param method 請求方法
     * @return  網路請求字串
     * @throws Exception
     */
    public static String net(String strUrl, Map params,String method) throws Exception {
        HttpURLConnection conn = null;
        BufferedReader reader = null;
        String rs = null;
        try {
            StringBuffer sb = new StringBuffer();
            if(method==null || method.equals("GET")){
                strUrl = strUrl+"?"+urlencode(params);
            }
            URL url = new URL(strUrl);
            conn = (HttpURLConnection) url.openConnection();
            if(method==null || method.equals("GET")){
                conn.setRequestMethod("GET");
            }else{
                conn.setRequestMethod("POST");
                conn.setDoOutput(true);
            }
            conn.setRequestProperty("User-agent", userAgent);
            conn.setUseCaches(false);
            conn.setConnectTimeout(DEF_CONN_TIMEOUT);
            conn.setReadTimeout(DEF_READ_TIMEOUT);
            conn.setInstanceFollowRedirects(false);
            conn.connect();
            if (params!= null && method.equals("POST")) {
                try {
                    DataOutputStream out = new DataOutputStream(conn.getOutputStream());
                        out.writeBytes(urlencode(params));
                } catch (Exception e) {
                    // TODO: handle exception
                }
            }
            InputStream is = conn.getInputStream();
            reader = new BufferedReader(new InputStreamReader(is, DEF_CHATSET));
            String strRead = null;
            while ((strRead = reader.readLine()) != null) {
                sb.append(strRead);
            }
            rs = sb.toString();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                reader.close();
            }
            if (conn != null) {
                conn.disconnect();
            }
        }
        return rs;
    }

    //將map型轉為請求引數型
    public static String urlencode(Map<String,Object>data) {
        StringBuilder sb = new StringBuilder();
        for (Map.Entry i : data.entrySet()) {
            try {
                sb.append(i.getKey()).append("=").append(URLEncoder.encode(i.getValue()+"","UTF-8")).append("&");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
}

這裡要注意的是：這裡針對的是web專案，如要測試請新建一個Servlet在瀏覽器進行訪問，控制檯輸出，得到的結果是JSONObject物件，根據不同的需求，進行分解轉化java物件；
JSONObject所需6個jar包，如有需要點選這裡可以免費下載http://download.csdn.net/detail/qq_33624284/9851046