Java进阶 - Java请求第三方接口代码示例

package commond;

import java.awt.*;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

public class HttpClient {

    /**
     * 向指定的URL发送GET请求
     * @param url 请求的url
     * @param param 请求的参数 拼接在url后面，应该是&key=value的格式
     * @param content_type 数据的格式
     * @return 所代表远程资源的响应结果
    */
    public static String sendGet(String url, String param, String content_type) {
        BufferedReader _in = null;
        String result = "";

        try {
            String _url = url + param;
            URL _realUrl = new URL(_url);
            //打开url连接
            URLConnection _urlConnection = _realUrl.openConnection();
            // 设置通用的请求属性
            _urlConnection.setRequestProperty("accept", "*/*");
            _urlConnection.setRequestProperty("connection", "Keep-Alive");
            _urlConnection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            _urlConnection.setRequestProperty("Content-Type", content_type);
            //建立实际的连接
            _urlConnection.connect();
            //获取所有的响应头字段
            Map<String, List<String>> _headerFields = _urlConnection.getHeaderFields();
            //遍历所有的响应头字段
            for(String key : _headerFields.keySet()){
                System.out.println(key + "------>" + _headerFields.get(key));
            }
            //获取响应结果
            _in = new BufferedReader(new                 
            InputStreamReader(_urlConnection.getInputStream()));
            //遍历并保存响应结果
            String line;
            while((line = _in.readLine()) != null){
                result += line;
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            try{
                if (_in != null){
                    _in.close();
                }
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定URL发送Post请求
     *
     * @param url          请求的url
     * @param param        请求的参数
     * @param content_type 数据格式
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param, String content_type) {
        PrintWriter _out = null;
        BufferedReader _in = null;
        String result = "";

        try {
            URL _url = new URL(url);
            //打开url连接
            URLConnection _urlConnection = _url.openConnection();
            // 设置通用的请求属性
            _urlConnection.setRequestProperty("accept", "*/*");
            _urlConnection.setRequestProperty("connection", "Keep-Alive");
            _urlConnection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            _urlConnection.setRequestProperty("Content-Type", content_type);
            //设置连接可用于输入/输出
            _urlConnection.setDoInput(true);
            _urlConnection.setDoInput(true);
            //获取URLConnection对象的输出流
            _out = new PrintWriter(_urlConnection.getOutputStream());
            //发送请求参数
            _out.print(param);
            //输出缓冲
            _out.flush();
            //获取响应结果
            _in = new BufferedReader(new 
            InputStreamReader(_urlConnection.getInputStream()));
            //遍历并保存响应结果
            String line;
            while ((line = _in.readLine()) != null) {
                result += line;
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
        //关闭输入输出流
        finally {
            try {
                if (_in != null) {
                    _in.close();
                }
                if (_out != null) {
                    _out.close();
                }
            }
            catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }
}