【Java】【20】后台发送GET/POST方法

前言：

1，get请求

2，post请求

3，post，get通用方法

4，其他的get，post写法

经过一段时间的检验，用方法3吧，比较好用。

【Java】【29】post，get通用方法加强 - 花生喂龙 - 博客园
https://www.cnblogs.com/huashengweilong/p/11028200.html

正文：

1，get请求

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;

// HTTP GET request
public static String SendGet(String url) {
    HttpClient client = new HttpClient();
    GetMethod method = new GetMethod(url);
    
    try {
        int statusCode = client.executeMethod(method);

        if (statusCode != HttpStatus.SC_OK) {
            logger.error("获取SendGet失败:" + method.getStatusLine());
        }
        
        return method.getResponseBodyAsString();
    } catch (HttpException e) {
        logger.error("获取SendGet失败: Fatal protocol violation", e);
    } catch (IOException e) {
        logger.error("获取SendGet失败: transport error", e);
    } finally {
          method.releaseConnection();
    }
    
    return "";
}

2，post请求

// HTTP POST
public static String SendPOST(String url) {
    HttpClient client = new HttpClient();
    PostMethod method = new PostMethod(url);
    
    try {
        int statusCode = client.executeMethod(method);

        if (statusCode != HttpStatus.SC_OK) {
            logger.error("获取SendPOST失败:" + method.getStatusLine());
        }
        
        return method.getResponseBodyAsString();
    } catch (HttpException e) {
        logger.error("获取SendPOST失败: Fatal protocol violation", e);
    } catch (IOException e) {
        logger.error("获取SendPOST失败: transport error", e);
    } finally {
          method.releaseConnection();
    }
    
    return "";
}

3，post，get通用方法

（1）返回的是json格式数据。根据我的使用情况来看，如果返回的是list数据，是要用JSONArray格式接收的，如果是多参数，用JSONObject。现在接口一般都会返回请求状态和错误原因及数据，所以用JSONObject接收就可以了

（2）HttpURLConnection代表请求的是http的URL，如果是https，需要用HttpsURLConnection

import net.sf.json.JSONObject;
import java.io.*;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.URL;

//post,get通用方法
public static JSONObject httpRequest(String requestUrl, String requestMethod, String outputStr)
{
    JSONObject jsonObject = null;
    StringBuffer buffer = new StringBuffer();
    try {
        URL url= new URL(requestUrl);
        HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();

        httpUrlConn.setDoOutput(true);
        httpUrlConn.setDoInput(true);
        httpUrlConn.setUseCaches(false);
        //设置请求方式（GET/POST）
        httpUrlConn.setRequestMethod(requestMethod);

        if ("GET".equalsIgnoreCase(requestMethod))
            httpUrlConn.connect();

        //当有数据需要提交时
        if (null != outputStr) {
            OutputStream outputStream = httpUrlConn.getOutputStream();
            //注意编码格式，防止中文乱码
            outputStream.write(outputStr.getBytes("UTF-8"));
            outputStream.close();
        }

        //将返回的输入流转换成字符串
        InputStream inputStream = httpUrlConn.getInputStream();
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

        String str = null;
        while ((str = bufferedReader.readLine()) != null) {
            buffer.append(str);
        }
        bufferedReader.close();
        inputStreamReader.close();
        //释放资源
        inputStream.close();
        httpUrlConn.disconnect();

        jsonObject = JSONObject.fromObject(buffer.toString());
    } catch (ConnectException ce) {
        logger.info("httpRequest: Weixin server connection timed out.");
    } catch (Exception e) {
        logger.info("httpRequest: error:{}" + e);
    }
    return jsonObject;
}

https的请求方法，大同小异

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;

//post,get通用方法
public static JSONObject httpRequest(String requestUrl, String requestMethod, String outputStr) 
{  
    JSONObject jsonObject = null;  
    StringBuffer buffer = new StringBuffer();  
    try {  
        //创建SSLContext对象，并使用我们指定的信任管理器初始化  
        TrustManager[] tm = { new MyX509TrustManager() };  
        SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");  
        sslContext.init(null, tm, new java.security.SecureRandom());  
        //从上述SSLContext对象中得到SSLSocketFactory对象  
        SSLSocketFactory ssf = sslContext.getSocketFactory();  

        URL url = new URL(requestUrl);  
        HttpsURLConnection httpUrlConn = (HttpsURLConnection) url.openConnection();  
        httpUrlConn.setSSLSocketFactory(ssf);  

        httpUrlConn.setDoOutput(true);  
        httpUrlConn.setDoInput(true);  
        httpUrlConn.setUseCaches(false);  
        //设置请求方式（GET/POST）  
        httpUrlConn.setRequestMethod(requestMethod);  

        if ("GET".equalsIgnoreCase(requestMethod))  
            httpUrlConn.connect();  

        //当有数据需要提交时  
        if (null != outputStr) {  
            OutputStream outputStream = httpUrlConn.getOutputStream();  
            //注意编码格式，防止中文乱码  
            outputStream.write(outputStr.getBytes("UTF-8"));  
            outputStream.close();  
        }  

        //将返回的输入流转换成字符串  
        InputStream inputStream = httpUrlConn.getInputStream();  
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");  
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);  

        String str = null;  
        while ((str = bufferedReader.readLine()) != null) {  
            buffer.append(str);  
        }  
        bufferedReader.close();  
        inputStreamReader.close();  
        //释放资源  
        inputStream.close();  
        inputStream = null;  
        httpUrlConn.disconnect();  
        
        jsonObject = JSONObject.fromObject(buffer.toString());  
    } catch (ConnectException ce) {  
        logger.info("httpRequest: Weixin server connection timed out.");  
    } catch (Exception e) {  
        logger.info("httpRequest: error:{}" + e);  
    }  
    return jsonObject;  
}  

MyX509TrustManager.class

import java.security.cert.CertificateException;  
import java.security.cert.X509Certificate;  
  
import javax.net.ssl.X509TrustManager;  
  
/** 
 * 证书信任管理器（用于https请求） 
 *  
 */  
public class MyX509TrustManager implements X509TrustManager {  
  
    public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {  
    }  
  
    public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {  
    }  
  
    public X509Certificate[] getAcceptedIssuers() {  
        return null;  
    }  
}  

4，其他的get，post写法

/**
     * 向指定URL发送GET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 name1=value1&name2=value2 的形式。
     * @return URL 所代表远程资源的响应结果
     */
    public static String sendGet(String url, String param) 
    {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            URL realUrl = new URL(urlNameString);
            // 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");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                map.get(key);
            }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }

        } catch (Exception e) {
            logger.info("发送GET请求出现异常:" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 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 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param) 
    {
        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", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 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);
            // 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) {
            logger.info("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;
    }

参考博客：

1，JAVA利用HttpClient进行HTTPS接口调用 - 路常有 - 博客园
https://www.cnblogs.com/luchangyou/p/6375166.html

2，使用httpclient实现后台java发送post和get请求 - myrui422的博客 - CSDN博客
https://blog.csdn.net/mhqyr422/article/details/79787518

3，Java发送http get/post请求，调用接口/方法 - 向前爬的蜗牛 - 博客园

https://www.cnblogs.com/wdpnodecodes/p/7807027.html