Httpclient与RestTemplate的比较（比httpClient更优雅的Restful URL访问）

一、HttpClient

（一）HttpClient 客户端

1、HttpClient 是 apache 的开源，需要引入两个包：httpclient-4.2.4.jar 和 httpcore-4.2.2.jar。

 

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/**  * HttpClien 的客户端访问  */  private void httpClientVisit() {          String clientResponse = "";      try {              HttpClient client = new DefaultHttpClient();          HttpPost request = new HttpPost(mUrl);              //不是表单数据提交，这边使用 StringEntity 即可          //UrlEncodedFormEntity等都是 HttpEntity 接口的实现类          StringEntity entity = new StringEntity(mRequestXml, "UTF-8");//编码          entity.setContentType("text/xml");          request.setEntity(entity);          // 发送请求          HttpResponse response = client.execute(request);              org.apache.http.HttpEntity httpEntity = response.getEntity();              if (httpEntity != null) {              // EntityUtils.toString 如果不指定编码，EntityUtils默认会使用ISO_8859_1进行编码              clientResponse = EntityUtils.toString(httpEntity, "UTF-8");// 记得设置编码或者如下              // clientResponse = new String(EntityUtils.toString(httpEntity).getBytes("ISO_8859_1"), "UTF-8");          }              if (clientResponse == null || "".equals(clientResponse)) {              System.err.println("clientResponse is null or empty.");              }              System.out.println(clientResponse);          } catch (Exception e) {          e.printStackTrace();      }      }

（二）HttpClient 详解

1、Post方式访问

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/**    * post方式提交表单（模拟用户登录请求）    */     public void postForm() {                String url = "http://localhost:8080/Java_WS_Server/rest/surpolicy/sendXml";               // 创建默认的httpClient实例.          HttpClient client = new DefaultHttpClient();       // 创建httppost           HttpPost httppost = new HttpPost(url);         // 创建参数队列           List<NameValuePair> formparams = new ArrayList<NameValuePair>();         formparams.add(new BasicNameValuePair("username", "admin"));         formparams.add(new BasicNameValuePair("password", "123456"));         UrlEncodedFormEntity uefEntity;         try {             uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8"); //编码            httppost.setEntity(uefEntity);             System.out.println("executing request " + httppost.getURI());             HttpResponse response = client.execute(httppost);    Header[] headers = response.getAllHeaders();  for(int i=0; i<headers.length; i++){      System.out.println(headers[i].getName());  }               try {                 HttpEntity entity = response.getEntity();                 if (entity != null) {                     System.out.println("--------------------------------------");                     System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8"));  //编码                   System.out.println("--------------------------------------");                 }             } finally {                 }         } catch (ClientProtocolException e) {             e.printStackTrace();         } catch (UnsupportedEncodingException e1) {             e1.printStackTrace();         } catch (IOException e) {             e.printStackTrace();         } finally {             }     }

　　2、Get方式访问

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/**   * 发送 get请求   */    public void get() {        try {            HttpClient client = new DefaultHttpClient();          // 创建httpget.              HttpGet httpget = new HttpGet("http://www.baidu.com/");            System.out.println("executing request " + httpget.getURI());            // 执行get请求.              HttpResponse response = client.execute(httpget);            try {                // 获取响应实体                  HttpEntity entity = response.getEntity();                System.out.println("--------------------------------------");                // 打印响应状态                  System.out.println(response.getStatusLine());                if (entity != null) {                    // 打印响应内容长度                      System.out.println("Response content length: " + entity.getContentLength());                    // 打印响应内容                      System.out.println("Response content: " + EntityUtils.toString(entity));                }                System.out.println("------------------------------------");            } finally {            }        } catch (ClientProtocolException e) {            e.printStackTrace();        }  catch (IOException e) {            e.printStackTrace();        } finally {}    }

　　

3、乱码问题：

1）利用：UrlEncodedFormEntity等 entity 容器，实现发送内容的编码：

 UrlEncodedFormEntity uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8"); //编码  

StringEntity entity = new StringEntity(mRequestXml, "UTF-8");//编码  

2、EntityUtils.toString()方法的转码，实现返回内容的编码：

  EntityUtils.toString 如果不指定编码，EntityUtils默认会使用ISO_8859_1进行编码  

clientResponse = EntityUtils.toString(httpEntity, "UTF-8");// 记得设置编码或者如下 

 clientResponse = new String(EntityUtils.toString(httpEntity).getBytes("ISO_8859_1"), "UTF-8");  

二、RestTemplate

 

（一）RestTemplate 客户端

1、RestTemplate 是Spring的封装，需要spring的包 spring-web-3.0.7.RELEASE.jar

2、客户端代码：

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/**  * RestTemplate 客户端访问  */  private void RestTemplateVisit() {      String returnXml = ""; // 核心返回结果报文字符串          try {              //复杂构造函数的使用          SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();          requestFactory.setConnectTimeout(1000);// 设置超时          requestFactory.setReadTimeout(1000);              //利用复杂构造器可以实现超时设置，内部实际实现为 HttpClient          RestTemplate restTemplate = new RestTemplate(requestFactory);              //设置HTTP请求头信息，实现编码等          HttpHeaders requestHeaders = new HttpHeaders();          // requestHeaders.set("Accept", "text/");          requestHeaders.set("Accept-Charset", "utf-8");          requestHeaders.set("Content-type", "text/xml; charset=utf-8");// 设置编码              //利用容器实现数据封装，发送          HttpEntity<String> entity = new HttpEntity<String>(mRequestXml, requestHeaders);          returnXml = restTemplate.postForObject(mUrl, entity, String.class);              // 转码原因：RestTemplate默认是使用org.springframework.http.converter.StringHttpMessageConverter来解析          // StringHttpMessageConverter 默认用的 ISO-8859-1来编码的          returnXml = new String(returnXml.getBytes("ISO-8859-1"), "utf-8");          } catch (UnsupportedEncodingException e) {          e.printStackTrace();      }          System.out.println("restTemplate客户端访问返回： \n" + returnXml);  }

　　具体的参考这个博客：

http://blog.youkuaiyun.com/u012228718/article/details/42028951

https://www.cnblogs.com/fengli9998/p/8028250.html