Java实现向指定URL用POST方法发送Json格式字符串参数请求的工具类

àì夳堔傛蜴生んèń 2023-10-18 15:58 21阅读 0赞

## 场景 ##

SpringBoot项目中通过后台Controller向某服务接口发送POST请求。

## 实现 ##

在项目pom.xml中添加依赖

<dependency>
                <groupId>commons-net</groupId>
                <artifactId>commons-net</artifactId>
                <version>2.2</version>
                <scope>compile</scope>
            </dependency>
            <dependency>
                <groupId>com.squareup.okhttp3</groupId>
                <artifactId>okhttp</artifactId>
                <version>3.6.0</version>
      </dependency>

在util包下新建HttpRequestUtil.java

public class HttpRequestUtil {
        /**
         * 定义全局OkHttpClient对象
         */
        private static final OkHttpClient httpClient = new OkHttpClient();
    
    /**
         * 向指定 URL 发送POST方法的请求
         *
         * @param url
         *            发送请求的 URL
         * @param param
         *            请求参数，请求参数应该是Json格式字符串的形式。
         * @return 所代表远程资源的响应结果
         */
        public static String sendPost(String url, String jsonData) {
            PrintWriter out = null;
            BufferedReader in = null;
            String result = "";
            try {
                URL realUrl = new URL(url);
                // 打开和URL之间的连接
                URLConnection con = realUrl.openConnection();
                HttpURLConnection conn = (HttpURLConnection) con;
                // 设置通用的请求属性
                conn.setRequestMethod("POST"); // 设置Post请求
                conn.setConnectTimeout(5 * 1000);
                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"); // 设置内容类型
                conn.setRequestProperty("Content-Type",
                        "application/json"); // 设置内容类型
                // conn.setRequestProperty("Content-Length",
                // String.valueOf(param.length())); //设置长度
                // 发送POST请求必须设置如下两行
                conn.setDoOutput(true);
                conn.setDoInput(true);
                conn.setUseCaches(false);
                // 获取URLConnection对象对应的输出流
                out = new PrintWriter(new OutputStreamWriter(
                        conn.getOutputStream(), "utf-8"));
                // 发送请求参数
                // out.print(param);
                out.write(jsonData);
                // 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;
                }
                byte[] bresult = result.getBytes();
                result = new String(bresult, "utf-8");
            } 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;
        }
    
    }

注意根据请求的enctype进行相应的设置

conn.setRequestProperty("Content-Type",
                        "application/x-www-form-urlencoded"); // 设置内容类型

或者

conn.setRequestProperty("Content-Type",
                        "application/json"); // 设置内容类型

在后台Controller调用时只需要：

String URL="http://IP:7788/PostPrintService/Info";
                Map map=new HashMap();
                map.put("TableName","wms_receive_order_details");
                map.put("PrintID",PrintId);
                String  param= JSON.toJSONString(map);
                String message = HttpRequestUtil.sendPost(URL, param);