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。
/** ?* 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
/** ???* 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
/** ??* 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：
/** ?* 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.csdn.net/u012228718/article/details/42028951
Httpclient与RestTemplate的比较（比httpClient更优雅的Restful URL访问）
原文地址：http://www.cnblogs.com/fengli9998/p/8028250.html