1 HttpClient簡(jiǎn)介
在JDK中java.net包下提供了用戶HTTP訪問的基本功能，但是它缺少靈活性或許多應(yīng)用所需要的功能。
? HttpClient起初是Apache Jakarta Common 的子項(xiàng)目。用來(lái)提供高效的、最新的、功能豐富的支持 HTTP 協(xié)議的客戶端編程工具包，并且它支持 HTTP 協(xié)議最新的版本。2007年成為頂級(jí)項(xiàng)目。
? 通俗解釋：HttpClient可以實(shí)現(xiàn)使用Java代碼完成標(biāo)準(zhǔn)HTTP請(qǐng)求及響應(yīng)。
2 代碼實(shí)現(xiàn)
2.1 服務(wù)端
新建項(xiàng)目HttpClientServer
2.1.1 新建控制器
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com.mrshun.controller.DemoController@Controllerpublic class DemoController { @RequestMapping("/demo") @ResponseBody public String demo(String param){ return "demo"+param; }} |
2.1.2 新建啟動(dòng)器
新建啟動(dòng)器
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com.mrshun.HttpClientServerApplication@SpringBootApplicationpublic class HttpClientServerApplication { public static void main(String[] args) { SpringApplication.run(HttpClientServerApplication.class,args); }} |
2.2 客戶端
新建HttpClientDemo項(xiàng)目
2.2.1 添加依賴
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<dependencies> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.10</version> </dependency></dependencies> |
2.2.2 新建類
新建com.mrshun.HttpClientDemo，編寫主方法。
2.2.2.1 使用GET方法訪問
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public static void main(String[] args) { try { //創(chuàng)建http工具（理解成:瀏覽器） 發(fā)起請(qǐng)求，解析響應(yīng) CloseableHttpClient httpClient = HttpClients.createDefault(); //請(qǐng)求路徑 URIBuilder uriBuilder = new URIBuilder("http://localhost:8080/demo"); uriBuilder.addParameter("param", "get123"); //創(chuàng)建HttpGet請(qǐng)求對(duì)象 HttpGet get = new HttpGet(uriBuilder.build()); //創(chuàng)建響應(yīng)對(duì)象 CloseableHttpResponse response = httpClient.execute(get); //由于響應(yīng)體是字符串，因此把HttpEntity類型轉(zhuǎn)換為字符串類型，并設(shè)置字符編碼 String result = EntityUtils.toString(response.getEntity(), "utf-8"); //輸出結(jié)果 System.out.println(result); //釋放資源 response.close(); httpClient.close(); } catch (URISyntaxException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }} |
2.2.2.2 使用POST方式訪問
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public class HttpClientDemo { public static void main(String[] args) { try { //創(chuàng)建http工具（理解成:瀏覽器） 發(fā)起請(qǐng)求，解析響應(yīng) CloseableHttpClient httpClient = HttpClients.createDefault(); //創(chuàng)建HttpPOST請(qǐng)求對(duì)象 HttpPost post = new HttpPost("http://localhost:8080/demo"); //所有請(qǐng)求參數(shù) List<NameValuePair> params = new ArrayList<>(); params.add(new BasicNameValuePair("param","123")); //創(chuàng)建HttpEntity接口的文本實(shí)現(xiàn)類的對(duì)象，放入?yún)?shù)并設(shè)置編碼 HttpEntity httpEntity = new UrlEncodedFormEntity(params,"utf-8"); //放入到HttpPost對(duì)象中 post.setEntity(httpEntity); //創(chuàng)建響應(yīng)對(duì)象 CloseableHttpResponse response = httpClient.execute(post); //由于響應(yīng)體是字符串，因此把HttpEntity類型轉(zhuǎn)換為字符串類型 String result = EntityUtils.toString(response.getEntity()); //輸出結(jié)果 System.out.println(result); //釋放資源 response.close(); httpClient.close(); } catch (IOException e) { e.printStackTrace(); } }} |
3. Jackson用法
3.1 把對(duì)象轉(zhuǎn)換為json字符串
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ObjectMapper objectMapper = new ObjectMapper();People peo = new People();objectMapper.writeValueAsString(peo); |
3.2 把json字符串轉(zhuǎn)換為對(duì)象
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ObjectMapper objectMapper = new ObjectMapper();People peo = objectMapper.readValue(content, People.class); |
3.3 把json字符串轉(zhuǎn)換為L(zhǎng)ist集合
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ObjectMapper objectMapper = new ObjectMapper();JavaType javaType = objectMapper.getTypeFactory().constructParametricType(List.class, People.class);List<People> list = objectMapper.readValue(content, javaType); |
4 HttpClient請(qǐng)求包含JSON
4.1 java代碼實(shí)現(xiàn)
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public class HttpClientDemo { public static void main(String[] args) { try { CloseableHttpClient httpClient = HttpClients.createDefault(); HttpPost post = new HttpPost("http://localhost:8080/demo"); HttpEntity httpEntity= null;String json = "{}"; StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON); post.setEntity(entity); CloseableHttpResponse response = httpClient.execute(post); String result = EntityUtils.toString(response.getEntity()); System.out.println(result); response.close(); httpClient.close(); } catch (IOException e) { e.printStackTrace(); } }} |
5 控制器接口參數(shù)
@RequestBody把請(qǐng)求體中流數(shù)據(jù)轉(zhuǎn)換為指定的對(duì)象。多用在請(qǐng)求參數(shù)是json數(shù)據(jù)且請(qǐng)求的Content-Type=”application/json”
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@RequestMapping("/demo4")@ResponseBodypublic String demo4(@RequestBody List<People> list) { System.out.println(list); return list.toString();} |
6 Ajax發(fā)送json參數(shù)寫法
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var json = '[{"id":123,"name":"mrshun"},{"id":123,"name":"zhangyongshun"}]'; $.ajax({ url:'/demo5', type:'post', success:function(data){ alert(data); for(var i = 0 ;i<data.length;i++){ alert(data[i].id +" "+data[i].name); } }, contentType:'application/json',//請(qǐng)求體中內(nèi)容類型 dataType:'json',//響應(yīng)內(nèi)容類型。 data:json }); |
7 跨域
- 跨域：協(xié)議、ip、端口中只要有一個(gè)不同就是跨域請(qǐng)求。
- 同源策略：瀏覽器默認(rèn)只允許ajax訪問同源(協(xié)議、ip、端口都相同)內(nèi)容。
解決同源策略：
? 在控制器接口上添加@CrossOrigin。表示允許跨域。本質(zhì)在響應(yīng)頭中添加Access-Control-Allow-Origin: *
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var json = '[{"id":123,"name":"mrshun"},{"id":456,"name":"zhangyongshun"}]'; $.ajax({ url:'/demo5', type:'post', success:function(data){ alert(data); for(var i = 0 ;i<data.length;i++){ alert(data[i].id +" "+data[i].name); } }, contentType:'application/json',//請(qǐng)求體中內(nèi)容類型 dataType:'json',//響應(yīng)內(nèi)容類型。 data:json }); |
到此這篇關(guān)于Java基于HttpClient實(shí)現(xiàn)RPC的示例的文章就介紹到這了,更多相關(guān)Java HttpClient實(shí)現(xiàn)RPC內(nèi)容請(qǐng)搜索服務(wù)器之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持服務(wù)器之家！
原文鏈接：https://blog.csdn.net/qq_46144237/article/details/120751147
