JAVA發送GET、POST請求

注意：本文使用 httpcomponents-client-4.4 版，和之前的 3.X 版本有較大區別。

1、建立一個servlet來接收get或post請求

package guwen;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.SAXReader;

public class TestServlet extends HttpServlet{

    /**
     * 接收get請求
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setCharacterEncoding("UTF-8");
        System.out.println(req.getQueryString());  //打印參數
        PrintWriter out = resp.getWriter();
        out.print("響應");  //響應
    }

    /**
     * 接收post請求
     */
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setCharacterEncoding("UTF-8");
        req.setCharacterEncoding("UTF-8");
        System.out.println(req.getQueryString());  //打印參數
        InputStream inputStream = req.getInputStream();
        SAXReader reader = new SAXReader();
        try {
            Document document = reader.read(inputStream);  //報文體
            System.out.println(document.asXML());
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        PrintWriter out = resp.getWriter();
        out.print("響應");  //響應
    }

    
}

2、發送請求

package guwen;

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;


public class ConnectionUtil {
    
    public static void main(String[] args) throws ClientProtocolException, IOException {
        //sent get
        sendGet("http://localhost:8088/sentTest/test?p=123");
        //sent post
        sendPost("http://localhost:8088/sentTest/test?p=321","<xml><a>aa</a><b>哈</b></xml>");
    }
    
    /**
     * 發送get請求
     * @throws IOException 
     */
    public static String sendGet(String url) throws ClientProtocolException, IOException {
        
        CloseableHttpClient httpClient = HttpClientBuilder.create().build();  
        
        HttpGet httpGet = new HttpGet(url);     
  
        //配置請求的超時設置  
        RequestConfig requestConfig = RequestConfig.custom()    
                .setConnectionRequestTimeout(50)  
                .setConnectTimeout(50)    
                .setSocketTimeout(50).build();    
        httpGet.setConfig(requestConfig);   
          
        CloseableHttpResponse response = null;
        String res = null;
        try {
            response = httpClient.execute(httpGet);   //發送請求
            System.out.println("StatusCode -> " + response.getStatusLine().getStatusCode());  
            HttpEntity entity = response.getEntity();          
            res = EntityUtils.toString(entity,"utf-8");   
            System.out.println(res);  
        } catch (ClientProtocolException e) {
            throw e;
        } catch (IOException e) {
            throw e;
        } finally{
            httpGet.releaseConnection(); 
        }
          
        return res;
    }
    
    
    
    /**
     * 發送post請求
     * @throws IOException 
     */
    public static String sendPost(String url,String body) throws IOException {
        
        CloseableHttpClient httpclient = HttpClientBuilder.create().build();  
        HttpPost httpPost = new HttpPost(url);
        //配置請求的超時設置  
        RequestConfig requestConfig = RequestConfig.custom()    
                .setConnectionRequestTimeout(50)  
                .setConnectTimeout(50)    
                .setSocketTimeout(50).build();    
        httpPost.setConfig(requestConfig); 
        
        CloseableHttpResponse response = null;
        String res = null;
        try {
            if (body != null) {  //設置報文體 設置編碼爲 UTF-8
                StringEntity entity = new StringEntity(body, "UTF-8");
                httpPost.setEntity(entity);
            }
            response = httpclient.execute(httpPost);  //發送請求
            System.out.println(response.toString());  
            
            HttpEntity entity = response.getEntity();  
            res = EntityUtils.toString(entity, "utf-8");  
            System.out.println(res);  
        } catch (ClientProtocolException e) {
            throw e;
        } catch (IOException e) {
            throw e;
        } finally{
            httpPost.releaseConnection();
        }
        
        return res;
        
        
    }
    
    
}