Atitit webclient httpclient技術總結 RestTemplate Atitit CateIT重要技術httpclient iduah2 impt 體系樹路徑：CS

在 Java 社群中，HTTP Client 主要有 JDK 的 HttpURLConnection、Apache Commons HttpClient（或被稱為 Apache HttpClient 3.x）、Apache HttpComponents Client（或被稱為 Apache HttpClient 4.x）、Square 公司開源的 OkHttp。

1. Rest工具 RestTemplate Feign

除了這幾個純粹的 HTTP Client 類庫以外，還有 Spring 的 RestTemplate、Square 公司的 Retrofit、Netflix 公司的 Feign，以及像 Apache CXF 中的 client 元件。這些框架和類庫主要是針對 Web Service 場景，尤其是 RESTful Web Service。它們往往是基於前面提到的 HTTP Client 實現，並在其基礎上提供了訊息轉換、引數對映等對於 Web Service 來說十分必要的功能。

1. Netty、Mina 這樣的網路 IO 框架過於底層

（當然，像 Netty、Mina 這樣的網路 IO 框架，實現 HTTP 自然也不再話下，但這些框架通常過於底層，不會被直接使用）

1. Curl postman

類似概念

1. WebClient（它會自動根據url來識別是FTP還是Http）

就是通過建立WebRequest（它會自動根據url來識別是FTP還是Http）來操作的。可以說，與其你費勁去建立HttpWebRequest，再建立WebResponse，最後才讀取資料，當然不如直接使用WebClient方便啦！但是這只是方便程度不同，對於你的這個問題沒有差別。

RestTemplate 的程式碼範例

1. url 攔截轉發器

* */

public class TransInterceptor extends HandlerInterceptorAdapter {

/**

* 。該方法的返回至是 Boolean 型別，當它返回 false 時，表示請求結束，後續的 Interceptor 和 Controller 都不會再執行；當它返回為 true 時會繼續呼叫下一個 Interceptor 的 preHandle 方法，如果已經是最後一個 Interceptor 的時候就會呼叫當前請求的 Controller 方法。

*/

@Override

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)

throws Exception {

String destUrl = "http://localhost:80"+request.getRequestURI();

long startTime = System.currentTimeMillis();

System.out.println("\n--------LogInterception.preHandle---");

if( request.getRequestURI().toLowerCase().startsWith("/actuator"))

return true;

System.out.println("RequestURL:" + request.getRequestURL());

System.out.println("StartTime:" + System.currentTimeMillis());

// response.getWriter().write( "攔截內容lejye neiron from svr proder.. ");

//

// if("1".equals("1"))

// return false;

// System.out.println(json);

// 構造URI。必須拼接出String url然後建立URI，否則會出現queryString %符號轉%25的問題

HttpMethod method = getHttpmethod(request);

URI destUri = new URI(destUrl+"?"+ getQueryString(request));

System.out.println(destUri);

HttpEntity<Object> requestEntity = getHttpHearderAndParams(request);

// 向服務請求

RestTemplate restTemplate = new RestTemplate();

ResponseEntity<String> responseEntity = restTemplate.exchange(destUri, method, requestEntity, String.class);

response.getWriter().write( responseEntity.getBody().toString());

// return responseEntity;

// request.setAttribute("startTime", startTime);

return false; //cancel next process

}

1. 提取標頭引數等

import javax.servlet.http.HttpServletRequest;

import org.springframework.http.HttpEntity;

import org.springframework.http.HttpHeaders;

import org.springframework.http.HttpMethod;

import org.springframework.util.LinkedMultiValueMap;

import org.springframework.util.MultiValueMap;

public class RestTemplateUtil {

public static HttpMethod getHttpmethod(HttpServletRequest request) {

HttpMethod method = null;

if (request.getMethod() == HttpMethod.POST.name())

method = HttpMethod.POST;

if (request.getMethod() .equals(HttpMethod.GET.name()) )

method = HttpMethod.GET;

return method;

}

public static String getQueryString(HttpServletRequest request) {

String destUrl = "";

if (request.getQueryString()!=null && !request.getQueryString().isEmpty())

destUrl += "?" + request.getQueryString();

return destUrl;

}

//請求實體

public static HttpEntity<Object> getHttpHearderAndParams(HttpServletRequest request) {

// 根據request，構造HttpHeaders

String body=null;

HttpHeaders headers = new HttpHeaders();

Enumeration<String> headerNames = request.getHeaderNames();

while(headerNames.hasMoreElements()){

String name = (String)headerNames.nextElement();

String value = request.getHeader(name);

headers.add(name, value);

}

// 複製 request 的引數

Map<String, String[]> parameterMap = request.getParameterMap();

MultiValueMap<String, Object> params = new LinkedMultiValueMap<String, Object>();

// 附加引數值

Set<String> keySet = parameterMap.keySet();

for (String key : keySet) {

String[] value = parameterMap.get(key);

params.add(key, value[0]);

}

// 根據body內容填充requestEntity。對於form-data，body為空但parameterMap有值；對於raw，body不為空。

HttpEntity<Object> requestEntity = (body!=null && !body.isEmpty())? new HttpEntity<>(body, headers): new HttpEntity<>(params, headers);

return requestEntity;

}

1. 並附帶帶cookie頭請求

import org.springframework.http.HttpEntity;

import org.springframework.http.HttpHeaders;

import org.springframework.http.HttpMethod;

import org.springframework.http.ResponseEntity;

import org.springframework.web.client.RestTemplate;

public class CookieTest {

/**

*

* array(1) {

["aaa"]=>

string(2) "11"

}

* @param args

* @throws URISyntaxException

*/

public static void main(String[] args) throws URISyntaxException {

HttpHeaders headers = new HttpHeaders();

headers.add("Cookie", "aaa=11" );

RestTemplate restTemplate = new RestTemplate();

// URI url= new URI("http://localhost:9088/cktest");

// System.out.println( restTemplate.getForObject(url, String.class));

String url = "http://localhost/showck.php";

url="http://localhost:9088/cktest";

ResponseEntity response = restTemplate.exchange(url,

HttpMethod.GET,

new HttpEntity (headers) ,String.class);

System.out.println(response.getBody());

//http://localhost/showck.php

}

Ref

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Atitit webclient httpclient技術總結 RestTemplate

Atitit CateIT重要技術httpclient iduah2 impt

體系樹路徑：CS IT> net . http ftp

密級和保密期限：：

Keywords和摘要：none

1. 內部概念 1

2. 常用工具技術 1

2.1. HttpClient OkHttp 2

2.2. Rest工具 RestTemplate Feign 2

2.3. Netty、Mina 這樣的網路 IO 框架過於底層 2

2.4. Curl postman 2

3. 類似概念 2

3.1. WebClient（它會自動根據url來識別是FTP還是Http） 3

4. RestTemplate 的程式碼範例 3

內部概念

1. 概念與組成 2

1.1. Httpentity 2

1.1.1. Fileentity 2

1.1.2. Stringentiry 2

1.1.3. Urlencodeformentity 2

1.2. Method 2

1.2.1. Get post put del 2

常用工具技術
1. HttpClient OkHttp

在 Java 社群中，HTTP Client 主要有 JDK 的 HttpURLConnection、Apache Commons HttpClient（或被稱為 Apache HttpClient 3.x）、Apache HttpComponents Client（或被稱為 Apache HttpClient 4.x）、Square 公司開源的 OkHttp。

1. Rest工具 RestTemplate Feign

除了這幾個純粹的 HTTP Client 類庫以外，還有 Spring 的 RestTemplate、Square 公司的 Retrofit、Netflix 公司的 Feign，以及像 Apache CXF 中的 client 元件。這些框架和類庫主要是針對 Web Service 場景，尤其是 RESTful Web Service。它們往往是基於前面提到的 HTTP Client 實現，並在其基礎上提供了訊息轉換、引數對映等對於 Web Service 來說十分必要的功能。

1. Netty、Mina 這樣的網路 IO 框架過於底層

（當然，像 Netty、Mina 這樣的網路 IO 框架，實現 HTTP 自然也不再話下，但這些框架通常過於底層，不會被直接使用）

1. Curl postman

類似概念

1. WebClient（它會自動根據url來識別是FTP還是Http）

就是通過建立WebRequest（它會自動根據url來識別是FTP還是Http）來操作的。可以說，與其你費勁去建立HttpWebRequest，再建立WebResponse，最後才讀取資料，當然不如直接使用WebClient方便啦！但是這只是方便程度不同，對於你的這個問題沒有差別。

RestTemplate 的程式碼範例

1. url 攔截轉發器

* */

public class TransInterceptor extends HandlerInterceptorAdapter {

/**

* 。該方法的返回至是 Boolean 型別，當它返回 false 時，表示請求結束，後續的 Interceptor 和 Controller 都不會再執行；當它返回為 true 時會繼續呼叫下一個 Interceptor 的 preHandle 方法，如果已經是最後一個 Interceptor 的時候就會呼叫當前請求的 Controller 方法。

*/

@Override

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)

throws Exception {

String destUrl = "http://localhost:80"+request.getRequestURI();

long startTime = System.currentTimeMillis();

System.out.println("\n--------LogInterception.preHandle---");

if( request.getRequestURI().toLowerCase().startsWith("/actuator"))

return true;

System.out.println("RequestURL:" + request.getRequestURL());

System.out.println("StartTime:" + System.currentTimeMillis());

// response.getWriter().write( "攔截內容lejye neiron from svr proder.. ");

//

// if("1".equals("1"))

// return false;

// System.out.println(json);

// 構造URI。必須拼接出String url然後建立URI，否則會出現queryString %符號轉%25的問題

HttpMethod method = getHttpmethod(request);

URI destUri = new URI(destUrl+"?"+ getQueryString(request));

System.out.println(destUri);

HttpEntity<Object> requestEntity = getHttpHearderAndParams(request);

// 向服務請求

RestTemplate restTemplate = new RestTemplate();

ResponseEntity<String> responseEntity = restTemplate.exchange(destUri, method, requestEntity, String.class);

response.getWriter().write( responseEntity.getBody().toString());

// return responseEntity;

// request.setAttribute("startTime", startTime);

return false; //cancel next process

}

1. 提取標頭引數等

import javax.servlet.http.HttpServletRequest;

import org.springframework.http.HttpEntity;

import org.springframework.http.HttpHeaders;

import org.springframework.http.HttpMethod;

import org.springframework.util.LinkedMultiValueMap;

import org.springframework.util.MultiValueMap;

public class RestTemplateUtil {

public static HttpMethod getHttpmethod(HttpServletRequest request) {

HttpMethod method = null;

if (request.getMethod() == HttpMethod.POST.name())

method = HttpMethod.POST;

if (request.getMethod() .equals(HttpMethod.GET.name()) )

method = HttpMethod.GET;

return method;

}

public static String getQueryString(HttpServletRequest request) {

String destUrl = "";

if (request.getQueryString()!=null && !request.getQueryString().isEmpty())

destUrl += "?" + request.getQueryString();

return destUrl;

}

//請求實體

public static HttpEntity<Object> getHttpHearderAndParams(HttpServletRequest request) {

// 根據request，構造HttpHeaders

String body=null;

HttpHeaders headers = new HttpHeaders();

Enumeration<String> headerNames = request.getHeaderNames();

while(headerNames.hasMoreElements()){

String name = (String)headerNames.nextElement();

String value = request.getHeader(name);

headers.add(name, value);

}

// 複製 request 的引數

Map<String, String[]> parameterMap = request.getParameterMap();

MultiValueMap<String, Object> params = new LinkedMultiValueMap<String, Object>();

// 附加引數值

Set<String> keySet = parameterMap.keySet();

for (String key : keySet) {

String[] value = parameterMap.get(key);

params.add(key, value[0]);

}

// 根據body內容填充requestEntity。對於form-data，body為空但parameterMap有值；對於raw，body不為空。

HttpEntity<Object> requestEntity = (body!=null && !body.isEmpty())? new HttpEntity<>(body, headers): new HttpEntity<>(params, headers);

return requestEntity;

}

1. 並附帶帶cookie頭請求

import org.springframework.http.HttpEntity;

import org.springframework.http.HttpHeaders;

import org.springframework.http.HttpMethod;

import org.springframework.http.ResponseEntity;

import org.springframework.web.client.RestTemplate;

public class CookieTest {

/**

*

* array(1) {

["aaa"]=>

string(2) "11"

}

* @param args

* @throws URISyntaxException

*/

public static void main(String[] args) throws URISyntaxException {

HttpHeaders headers = new HttpHeaders();

headers.add("Cookie", "aaa=11" );

RestTemplate restTemplate = new RestTemplate();

// URI url= new URI("http://localhost:9088/cktest");

// System.out.println( restTemplate.getForObject(url, String.class));

String url = "http://localhost/showck.php";

url="http://localhost:9088/cktest";

ResponseEntity response = restTemplate.exchange(url,

HttpMethod.GET,

new HttpEntity (headers) ,String.class);

System.out.println(response.getBody());

//http://localhost/showck.php

}

Ref