java 发送http请求【get、post、post(json数据)）】

深碍√TFBOYSˉ_ 2021-10-15 13:04 472阅读 0赞

#### 一、发送Get请求 ####

ublic static String sendGet(String url, String param) {
            PrintWriter out = null;
            BufferedReader in = null;
            String result = "";
            String reaUrl = url + "?" + param;
            try {
                URL realUrl = new URL(reaUrl);
                // 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)");
                //建立真正的连接
                connection.connect();
                Map<String, List<String>> map = connection.getHeaderFields();
                for(String key : map.keySet()) {
                    System.out.println("key -->" + map.get(key));
                }
    
                in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line = "";
                while ((line = in.readLine()) != null) {
                    result += line + "\n";
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if (in != null) {
                        in.close();
                    }
                    if (out != null) {
                        out.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
    
            return result;
        }

#### 二、发送post请求 ####

public static String sendPost(String url, String string) {
            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", "KeepAlive");
                conn.setRequestProperty("user-agent", "Mozilla/4.0(compatible; MSIE 6.0; Windows NT 5.1;SV1)");
                conn.setDoOutput(true);  //由于URLConnection在默认情况下不允许输出，所以在请求输出流之前必须将其设置为true，此时请求方式由get变为post
                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(string);
                // 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 (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if(out != null) {
                        out.close();
                    }
                    if(in != null) {
                        in.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return result;
        }

#### 三、通过post请求发送json数据 ####

/**
         * 参数json为json格式的字符串
         * @param urlStr
         * @param json
         * @return
         */
        public static String sendPostByJSON(String urlStr, String json) {
            OutputStreamWriter outputStreamWriter = null;
            BufferedReader bufferedReader = null;
            String response = "";
    
            try {
                URL url = new URL(urlStr);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setDoInput(true);
                connection.setDoOutput(true);
                connection.setUseCaches(false);
                connection.setRequestMethod("POST");      //POST需大写
                connection.setRequestProperty("content-Type", "application/json");        //设置数据格式为json
                connection.setRequestProperty("charset", "utf-8");                        //设置编码格式为utf-8
                connection.connect();
    
                outputStreamWriter = new OutputStreamWriter(connection.getOutputStream());
                outputStreamWriter.append(json);
                outputStreamWriter.flush();
    
                bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));
                String line = "";
                while((line = bufferedReader.readLine()) != null) {
                    response += line;
                }
    
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    outputStreamWriter.close();
                    bufferedReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return response;
        }

四、通过代理发送post请求

public static String sendPost(String url, String param,boolean isproxy) {
        OutputStreamWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            HttpURLConnection conn = null;
            if(isproxy){//使用代理模式
                @SuppressWarnings("static-access")
                Proxy proxy = new Proxy(Proxy.Type.DIRECT.HTTP, new InetSocketAddress(proxyHost, proxyPort));//proxyHost和proxyPort是代理服务器的地址和端口号
                conn = (HttpURLConnection) realUrl.openConnection(proxy);
            }else{
                conn = (HttpURLConnection) realUrl.openConnection();
            }
            // 打开和URL之间的连接
    
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setRequestMethod("POST");    // POST方法
    
            // 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)");
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    
            conn.connect();
    
            // 获取URLConnection对象对应的输出流
            out = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
            // 发送请求参数
            out.write(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;
    }