Java发送post方法

总结一下java使用http发送post的方法：

1、post请求用于发送json 格式的参数：

/**
     * post请求（用于请求json格式的参数）
     *
     * @param url    地址
     * @param params json格式的参数
     * @return
     */
    public static String doPost(String url, String params) throws Exception {

        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost( url );// 创建httpPost
        httpPost.setHeader( "Accept", "application/json" );
        httpPost.setHeader( "Content-Type", "application/json" );
        String charSet = "UTF-8";
        StringEntity entity = new StringEntity( params, charSet );
        httpPost.setEntity( entity );
        CloseableHttpResponse response = null;

        try {

            response = httpclient.execute( httpPost );
            StatusLine status = response.getStatusLine();
            int state = status.getStatusCode();
            if (state == HttpStatus.SC_OK) {
                HttpEntity responseEntity = response.getEntity();
                String jsonString = EntityUtils.toString( responseEntity );
                return jsonString;
            } else {
                logger.error( "请求返回:" + state + "(" + url + ")" );
            }
        } finally {
            if (response != null) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

2、用于发送key-value格式的参数

/**
     * post请求(用于key-value格式的参数)
     *
     * @param url
     * @param params
     * @return
     */
    public static String doPost(String url, Map params) {

        BufferedReader in = null;
        try {
            // 定义HttpClient
            HttpClient client = new DefaultHttpClient();
            // 实例化HTTP方法
            HttpPost request = new HttpPost();
            request.setURI( new URI( url ) );

            //设置参数
            List<NameValuePair> nvps = new ArrayList<NameValuePair>();
            for (Iterator iter = params.keySet().iterator(); iter.hasNext(); ) {
                String name = (String) iter.next();
                String value = String.valueOf( params.get( name ) );
                nvps.add( new BasicNameValuePair( name, value ) );

                //System.out.println(name +"-"+value);
            }
            request.setEntity( new UrlEncodedFormEntity( nvps, HTTP.UTF_8 ) );

            HttpResponse response = client.execute( request );
            int code = response.getStatusLine().getStatusCode();
            if (code == 200) {    //请求成功
                in = new BufferedReader( new InputStreamReader( response.getEntity()
                        .getContent(), "utf-8" ) );
                StringBuffer sb = new StringBuffer( "" );
                String line = "";
                String NL = System.getProperty( "line.separator" );
                while ((line = in.readLine()) != null) {
                    sb.append( line + NL );
                }
                in.close();

                return sb.toString();
            } else {    //
                System.out.println( "状态码：" + code );
                return null;
            }
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

第三，发送get请求

   /**
     * get请求
     *
     * @return
     */
    public static String doGet(String url) {
        try {
            HttpClient client = new DefaultHttpClient();
            //发送get请求
            HttpGet request = new HttpGet( url );
            HttpResponse response = client.execute( request );
            /**请求发送成功，并得到响应**/
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                /**读取服务器返回过来的json字符串数据**/
                String strResult = EntityUtils.toString( response.getEntity() );
                return strResult;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }