Java模仿http请求工具类

package ln;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 用于模拟HTTP请求中GET/POST方式
 * @author landa
 *
 */
public class HttpUtils {
    /**
     * 发送GET请求
     *
     * @param url
     *            目的地址
     * @param parameters
     *            请求参数，Map类型。
     * @return 远程响应结果
     */
    public static String sendGet(String url, Map<String, String> parameters) {
        String result="";
        BufferedReader in = null;// 读取响应输入流
        StringBuffer sb = new StringBuffer();// 存储参数
        String params = "";// 编码之后的参数
        try {
            // 编码请求参数
            if(parameters.size()==1){
                for(String name:parameters.keySet()){
                    sb.append(name).append("=").append(
                            java.net.URLEncoder.encode(parameters.get(name),
                            "UTF-8"));
                }
                params=sb.toString();
            }else{
                for (String name : parameters.keySet()) {
                    sb.append(name).append("=").append(
                            java.net.URLEncoder.encode(parameters.get(name),
                                    "UTF-8")).append("&");
                }
                String temp_params = sb.toString();
                params = temp_params.substring(0, temp_params.length() - 1);
            }
            String full_url = url + "?" + params;
            System.out.println(full_url);
            // 创建URL对象
            java.net.URL connURL = new java.net.URL(full_url);
            // 打开URL连接
            java.net.HttpURLConnection httpConn = (java.net.HttpURLConnection) connURL
                    .openConnection();
            // 设置通用属性
            httpConn.setRequestProperty("Accept", "*/*");
            httpConn.setRequestProperty("Connection", "Keep-Alive");
            httpConn.setRequestProperty("User-Agent",
                    "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1)");
            // 建立实际的连接
            httpConn.connect();
            // 响应头部获取
            Map<String, List<String>> headers = httpConn.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : headers.keySet()) {
                System.out.println(key + "\t：\t" + headers.get(key));
            }
            // 定义BufferedReader输入流来读取URL的响应,并设置编码方式
            in = new BufferedReader(new InputStreamReader(httpConn
                    .getInputStream(), "UTF-8"));
            String line;
            // 读取返回的内容
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result ;
    }  

    /**
     * 发送POST请求
     *
     * @param url
     *            目的地址
     * @param parameters
     *            请求参数，Map类型。
     * @return 远程响应结果
     */
    public static String sendPost(String url, Map<String, String> parameters) {
        String result = "";// 返回的结果
        BufferedReader in = null;// 读取响应输入流
        PrintWriter out = null;
        StringBuffer sb = new StringBuffer();// 处理请求参数
        String params = "";// 编码之后的参数
        try {
            // 编码请求参数
            if (parameters.size() == 1) {
                for (String name : parameters.keySet()) {
                    sb.append(name).append("=").append(
                            java.net.URLEncoder.encode(parameters.get(name),
                                    "UTF-8"));
                }
                params = sb.toString();
            } else {
                for (String name : parameters.keySet()) {
                    sb.append(name).append("=").append(
                            java.net.URLEncoder.encode(parameters.get(name),
                                    "UTF-8")).append("&");
                }
                String temp_params = sb.toString();
                params = temp_params.substring(0, temp_params.length() - 1);
            }
            // 创建URL对象
            java.net.URL connURL = new java.net.URL(url);
            // 打开URL连接
            java.net.HttpURLConnection httpConn = (java.net.HttpURLConnection) connURL
                    .openConnection();
            // 设置通用属性
            httpConn.setRequestProperty("Accept", "*/*");
            httpConn.setRequestProperty("Connection", "Keep-Alive");
            httpConn.setRequestProperty("User-Agent",
                    "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1)");
            // 设置POST方式
            httpConn.setDoInput(true);
            httpConn.setDoOutput(true);
            // 获取HttpURLConnection对象对应的输出流
            out = new PrintWriter(httpConn.getOutputStream());
            // 发送请求参数
            out.write(params);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应，设置编码方式
            in = new BufferedReader(new InputStreamReader(httpConn
                    .getInputStream(), "UTF-8"));
            String line;
            // 读取返回的内容
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }  

    /**
     * 主函数，测试请求
     *
     * @param args
     */
    public static void main(String[] args) {
        Map<String, String> parameters = new HashMap<String, String>();
        parameters.put("name", "sarin");
        String result =sendGet("http://www.baidu.com", parameters);
        System.out.println(result);
    }
}

转载：https://www.cnblogs.com/vitre/p/5474166.html