Example tutorial of calling interface in java

1. First URL restURL = new URL(url); The url is the target interface address that needs to be adjusted, and the URL class is java.net.* category under.

2, setRequestMethod("POST"); The request method has two values ​​to choose from, one is GET and the other is POST, select the corresponding request method

3. setDoOutput(true);setDoInput(true);

setDoInput():  // 设置是否向httpUrlConnection输出，因为这个是post请求，参数要放在http正文内，
因此需要设为true, 默认是false;   
setDoOutput():   // 设置是否从httpUrlConnection读入，默认情况下是true;

4. setAllowUserInteraction();allowUserInteraction If true, user interaction is allowed (such as pop-up This URL is checked within the context of a validation dialog box.

5. The query in the following code is transmitted in the form of "attribute=value". If there are multiple queries, it is passed in the form of "attribute=value&attribute=value". It is passed to the server and let the server handle it by itself.

6, close();Create a stream to write or read the return value. Remember to close the stream after creation.

Example tutorial:

package com.c;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

public class RestUtil {

    public String load(String url,String query) throws Exception
    {
        URL restURL = new URL(url);
        /*
         * 此处的urlConnection对象实际上是根据URL的请求协议(此处是http)生成的URLConnection类 的子类
         HttpURLConnection
         */
        HttpURLConnection conn = (HttpURLConnection) restURL.openConnection();
        //请求方式
        conn.setRequestMethod("POST");
        //设置是否从httpUrlConnection读入，默认情况下是true; httpUrlConnection.setDoInput(true);
        conn.setDoOutput(true);
        //allowUserInteraction 如果为 true，则在允许用户交互（例如弹出一个验证对话框）的上下文中对此 URL 进行检查。
        conn.setAllowUserInteraction(false);

        PrintStream ps = new PrintStream(conn.getOutputStream());
        ps.print(query);

        ps.close();

        BufferedReader bReader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

        String line,resultStr="";

        while(null != (line=bReader.readLine()))
        {
        resultStr +=line;
        }
        System.out.println("3412412---"+resultStr);
        bReader.close();

        return resultStr;

    }
     
    public static void main(String []args) {try {

            RestUtil restUtil = new RestUtil();

            String resultString = restUtil.load(
                    "http://192.168.10.89:8080/eoffice-restful/resources/sys/oaholiday",
                    "floor=first&year=2017&month=9&isLeader=N");

            } catch (Exception e) {

            // TODO: handle exception

            System.out.print(e.getMessage());

            }

        }
}

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