java如何發起http請求呼叫post與get接口

一、java呼叫post介面

1、使用URLConnection或HttpURLConnection

java自帶的，無須下載其他jar套件

URLConnection方式調用，如果介面回應碼被服務端修改則無法接收到返回封包，只能當回應碼正確時才能接收到返回

public static String sendPost(String url, String param) {
        OutputStreamWriter out = null;
        BufferedReader in = null;
        StringBuilder result = new StringBuilder("");
        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("Content-Type","application/json;charset=UTF-8");
            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 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(),"UTF-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result.append(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{
        	if(out!=null){ try { out.close(); }catch(Exception ex){} }
        	if(in!=null){ try { in.close(); }catch(Exception ex){} }
        }
        return result.toString();
    }

HttpURLConnection方式呼叫

#

//ms超时毫秒,url地址,json入参
public static String httpJson(int ms,String url,String json) throws Exception{
		String err = "00", line = null;
		StringBuilder sb = new StringBuilder();
		HttpURLConnection conn = null;
		BufferedWriter out = null;
		BufferedReader in = null;
		try{
			conn = (HttpURLConnection) (new URL(url.replaceAll("／","/"))).openConnection();
			conn.setRequestMethod("POST");
			conn.setDoOutput(true);
			conn.setDoInput(true);
			conn.setUseCaches(false);
			conn.setConnectTimeout(ms);
			conn.setReadTimeout(ms);
			conn.setRequestProperty("Content-Type","application/json;charset=utf-8");
			conn.connect();
			out = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(),"utf-8"));
			out.write(new String(json.getBytes(), "utf-8"));
			out.flush();//发送参数
			int code = conn.getResponseCode();
			if (conn.getResponseCode()==200){
				in = new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));
				while ((line=in.readLine())!=null)
					sb.append(line);
			}//接收返回值
			
		}catch(Exception ex){
			err=ex.getMessage();
		}
		try{ if (out!=null) out.close(); }catch(Exception ex){}; 
		try{ if (in!=null) in.close(); }catch(Exception ex){};
		try{ if (conn!=null) conn.disconnect();}catch(Exception ex){}
		if (!err.equals("00")) throw new Exception(err);
		return sb.toString();
	}

2、使用CloseableHttpClient

使用的jar包

<dependency>
    <groupId>com.alibaba.csb.sdk</groupId>
    <artifactId>http-client</artifactId>
    <version>1.1.5.1</version>
</dependency>

public static String httpPostJson(String url,String json) throws Exception{
		String data=""; 
		CloseableHttpClient httpClient = null;
		CloseableHttpResponse response = null;
		try {
			httpClient = HttpClients.createDefault();
			HttpPost httppost = new HttpPost(url);
			httppost.setHeader("Content-Type", "application/json;charset=UTF-8");
			StringEntity se = new StringEntity(json,Charset.forName("UTF-8"));
	        se.setContentType("text/json");
	        se.setContentEncoding("UTF-8");
	        httppost.setEntity(se);
	        response = httpClient.execute(httppost);
	        int code = response.getStatusLine().getStatusCode();
	        System.out.println("接口响应码:"+code);
	        data = EntityUtils.toString(response.getEntity(), "utf-8");
	        EntityUtils.consume(response.getEntity());
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if(response!=null){ try{response.close();}catch (IOException e){} }
			if(httpClient!=null){ try{httpClient.close();}catch(IOException e){} }
		}
		return data;
	}

3、使用HttpCaller

使用的jar包同第2個中的jar包。

public static String sendPost(){
		String result = "";
		HttpParameters.Builder builder = HttpParameters.newBuilder();
		builder.requestURL("URL") // 设置请求的URL
        		.api("api") // 设置服务名
        		.version("version") // 设置版本号
        		.method("post") // 设置调用方式, get/post
        		.accessKey("ak").secretKey("sk"); // 设置accessKey 和 设置secretKey
		// 设置请求参数（json格式)
        Map<String,String> param = new HashMap<String,String>();
        param.put("key1","value1");
        param.put("key2","value2");
        //加密，没有加密则不需要encryptParam，直接用param
        Map<String,String> encryptParam = new HashMap<String,String>();
        encryptParam.put("key3", getData(JSON.toJSONString(param)));
        ContentBody cb = new ContentBody(JSON.toJSONString(encryptParam));
        builder.contentBody(cb);
        
        try {
        	result = HttpCaller.invoke(builder.build());
		} catch (Exception e) {
			e.printStackTrace();
		}
		
        return result;
	}
	
	//自己的加密方式
	public static String getData(String data1){
		return "加密后的密文";
	}

二、java呼叫get介面

使用java自帶的URLConnection

//将map型转为请求参数型
public static String getUrlData(Map<Object, Object> data) throws Exception{
	StringBuffer sb = new StringBuffer();
	try {
		Set<Map.Entry<Object, Object>> entries = data.entrySet();
		Iterator<Map.Entry<Object, Object>> iterators = entries.iterator();
		while(iterators.hasNext()){
			Map.Entry<Object, Object> next = iterators.next();
			sb.append(next.getKey().toString().trim()).append("=").append(URLEncoder.encode(next.getValue() + "", "UTF-8").trim()).append("&");
		}
		sb.deleteCharAt(sb.length() - 1);
	} catch (Exception e) {
		sb.append(e.toString());
	}
	return sb.toString();
}

//strUrl截止到?，例：http://127.0.0.1:8080/api/method?
public static String httpGet(String strUrl){
	Map<Object, Object> params = new HashMap<Object, Object>();
	params.put("key1", "value1");
	params.put("key2", "value2");
	String url=strUrl + getUrlData(params);
	
  	StringBuilder result = new StringBuilder();
    BufferedReader in = null;
    try {
        URL realUrl = new URL(url);
        // 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)");
        // 建立实际的连接
        connection.connect();
        // 获取所有响应头字段
        // 定义 BufferedReader输入流来读取URL的响应
        in = new BufferedReader(new InputStreamReader(connection.getInputStream(),"UTF-8"));
        String line;
        while ((line = in.readLine()) != null) {
            result.append(line);
        }
    } catch (Exception e) {
        System.out.println("发送GET请求出现异常！" + e);
        e.printStackTrace();
    }
    finally {
    	if (in != null){ try { in.close(); }catch(Exception e2){} }
    }
    return result.toString();
}

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