使用httpClient发送getpost请求

maven依赖

<dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.2</version>
    </dependency>

GET请求：

1、参数直接拼接到URL后面，即http://test.com?a=1&b=2的形式

/**
     * get请求，参数拼接在地址上
     * @param url 请求地址加参数
     * @return 响应
     */
    public String get(String url)
    {
        String result = null;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet get = new HttpGet(url);
        CloseableHttpResponse response = null;
        try {
            response = httpClient.execute(get);
            if(response != null && response.getStatusLine().getStatusCode() == 200)
            {
                HttpEntity entity = response.getEntity();
                result = entityToString(entity);
            }
            return result;
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                httpClient.close();
                if(response != null)
                {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

2、参数放置到一个map中

/**
     * get请求，参数放在map里
     * @param url 请求地址
     * @param map 参数map
     * @return 响应
     */
    public String getMap(String url,Map<String,String> map)
    {
        String result = null;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        List<NameValuePair> pairs = new ArrayList<NameValuePair>();
        for(Map.Entry<String,String> entry : map.entrySet())
        {
            pairs.add(new BasicNameValuePair(entry.getKey(),entry.getValue()));
        }
        CloseableHttpResponse response = null;
        try {
            URIBuilder builder = new URIBuilder(url);
            builder.setParameters(pairs);
            HttpGet get = new HttpGet(builder.build());
            response = httpClient.execute(get);
            if(response != null && response.getStatusLine().getStatusCode() == 200)
            {
                HttpEntity entity = response.getEntity();
                result = entityToString(entity);
            }
            return result;
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                httpClient.close();
                if(response != null)
                {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return null;
    }

POST请求：

1、参数放到map中

/**
     * 发送post请求，参数用map接收
     * @param url 地址
     * @param map 参数
     * @return 返回值
     */
    public String postMap(String url,Map<String,String> map) {
        String result = null;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost post = new HttpPost(url);
        List<NameValuePair> pairs = new ArrayList<NameValuePair>();
        for(Map.Entry<String,String> entry : map.entrySet())
        {
            pairs.add(new BasicNameValuePair(entry.getKey(),entry.getValue()));
        }
        CloseableHttpResponse response = null;
        try {
            post.setEntity(new UrlEncodedFormEntity(pairs,"UTF-8"));
            response = httpClient.execute(post);
            if(response != null && response.getStatusLine().getStatusCode() == 200)
            {
                HttpEntity entity = response.getEntity();
                result = entityToString(entity);
            }
            return result;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                httpClient.close();
                if(response != null)
                {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        return null;
    }

2、参数是json字符串

/**
     * post请求，参数为json字符串
     * @param url 请求地址
     * @param jsonString json字符串
     * @return 响应
     */
    public String postJson(String url,String jsonString)
    {
        String result = null;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost post = new HttpPost(url);
        CloseableHttpResponse response = null;
        try {
            post.setEntity(new ByteArrayEntity(jsonString.getBytes("UTF-8")));
            response = httpClient.execute(post);
            if(response != null && response.getStatusLine().getStatusCode() == 200)
            {
                HttpEntity entity = response.getEntity();
                result = entityToString(entity);
            }
            return result;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                httpClient.close();
                if(response != null)
                {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

entityToString方法：

private String entityToString(HttpEntity entity) throws IOException {
        String result = null;
        if(entity != null)
        {
            long lenth = entity.getContentLength();
            if(lenth != -1 && lenth < 2048)
            {
                result = EntityUtils.toString(entity,"UTF-8");
            }else {
                InputStreamReader reader1 = new InputStreamReader(entity.getContent(), "UTF-8");
                CharArrayBuffer buffer = new CharArrayBuffer(2048);
                char[] tmp = new char[1024];
                int l;
                while((l = reader1.read(tmp)) != -1) {
                    buffer.append(tmp, 0, l);
                }
                result = buffer.toString();
            }
        }
        return result;
    }