Atitit webclient httpclient技术总结 RestTemplate Atitit CateIT重要技术httpclient iduah2 impt 体系树路径：CS

在 Java 社区中，HTTP Client 主要有 JDK 的 HttpURLConnection、Apache Commons HttpClient（或被称为 Apache HttpClient 3.x）、Apache HttpComponents Client（或被称为 Apache HttpClient 4.x）、Square 公司开源的 OkHttp。

1. Rest工具 RestTemplate Feign

除了这几个纯粹的 HTTP Client 类库以外，还有 Spring 的 RestTemplate、Square 公司的 Retrofit、Netflix 公司的 Feign，以及像 Apache CXF 中的 client 组件。这些框架和类库主要是针对 Web Service 场景，尤其是 RESTful Web Service。它们往往是基于前面提到的 HTTP Client 实现，并在其基础上提供了消息转换、参数映射等对于 Web Service 来说十分必要的功能。

1. Netty、Mina 这样的网络 IO 框架过于底层

（当然，像 Netty、Mina 这样的网络 IO 框架，实现 HTTP 自然也不再话下，但这些框架通常过于底层，不会被直接使用）

1. Curl postman

类似概念

1. WebClient（它会自动根据url来识别是FTP还是Http）

就是通过创建WebRequest（它会自动根据url来识别是FTP还是Http）来操作的。可以说，与其你费劲去创建HttpWebRequest，再创建WebResponse，最后才读取数据，当然不如直接使用WebClient方便啦！但是这只是方便程度不同，对于你的这个问题没有差别。

RestTemplate 的代码范例

1. url 拦截转发器

* */

public class TransInterceptor extends HandlerInterceptorAdapter {

/**

* 。该方法的返回至是 Boolean 类型，当它返回 false 时，表示请求结束，后续的 Interceptor 和 Controller 都不会再执行；当它返回为 true 时会继续调用下一个 Interceptor 的 preHandle 方法，如果已经是最后一个 Interceptor 的时候就会调用当前请求的 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( "拦截内容lejye neiron from svr proder.. ");

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

// return false;

// System.out.println(json);

// 构造URI。必须拼接出String url然后创建URI，否则会出现queryString %符号转%25的问题

HttpMethod method = getHttpmethod(request);

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

System.out.println(destUri);

HttpEntity<Object> requestEntity = getHttpHearderAndParams(request);

// 向服务请求

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. 提取标头参数等

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;

}

//请求实体

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

// 根据request，构造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);

}

// 复制 request 的参数

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

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

// 附加参数值

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

for (String key : keySet) {

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

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

}

// 根据body内容填充requestEntity。对于form-data，body为空但parameterMap有值；对于raw，body不为空。

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

return requestEntity;

}

1. 并附带带cookie头请求

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技术总结 RestTemplate

Atitit CateIT重要技术httpclient iduah2 impt

体系树路径：CS IT> net . http ftp

密级和保密期限：：

Keywords和摘要：none

1. 内部概念 1

2. 常用工具技术 1

2.1. HttpClient OkHttp 2

2.2. Rest工具 RestTemplate Feign 2

2.3. Netty、Mina 这样的网络 IO 框架过于底层 2

2.4. Curl postman 2

3. 类似概念 2

3.1. WebClient（它会自动根据url来识别是FTP还是Http） 3

4. RestTemplate 的代码范例 3

内部概念

1. 概念与组成 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

常用工具技术
1. HttpClient OkHttp

1. Rest工具 RestTemplate Feign

1. Netty、Mina 这样的网络 IO 框架过于底层

（当然，像 Netty、Mina 这样的网络 IO 框架，实现 HTTP 自然也不再话下，但这些框架通常过于底层，不会被直接使用）

1. Curl postman

类似概念

1. WebClient（它会自动根据url来识别是FTP还是Http）

RestTemplate 的代码范例

1. url 拦截转发器

* */

public class TransInterceptor extends HandlerInterceptorAdapter {

/**

@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( "拦截内容lejye neiron from svr proder.. ");

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

// return false;

// System.out.println(json);

// 构造URI。必须拼接出String url然后创建URI，否则会出现queryString %符号转%25的问题

HttpMethod method = getHttpmethod(request);

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

System.out.println(destUri);

HttpEntity<Object> requestEntity = getHttpHearderAndParams(request);

// 向服务请求

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. 提取标头参数等

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;

}

//请求实体

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

// 根据request，构造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);

}

// 复制 request 的参数

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

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

// 附加参数值

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

for (String key : keySet) {

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

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

}

// 根据body内容填充requestEntity。对于form-data，body为空但parameterMap有值；对于raw，body不为空。

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

return requestEntity;

}

1. 并附带带cookie头请求

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