HttpClient

HttpClient 简介

HttpClient 是 Apache Jakarta Common 下的子项目,可以用来提供高效的、最新的、
功能丰富的支持 HTTP 协议的客户端编程工具包,并且它支持 HTTP 协议最新的版本和
建议。
HTTP 协议可能是现在 Internet 上使用得最多、最重要的协议了,越来越多的 Java
应用程序需要直接通过 HTTP 协议来访问网络资源。虽然在 JDK 的 java net 包中已经提
供了访问 HTTP 协议的基本功能,但是对于大部分应用程序来说, JDK 库本身提供的功能
还不够丰富和灵活。
二、 HttpClient 应用
1 发送 GET 请求不带参数

1.1 创建项目

 

1.2 修改 POM 文件

添加 HttpClient 坐标

<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instan
ce"
xsi:schemaLocation="http://maven.apache.org/P
OM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.bjsxt</groupId>
<artifactId>httpClientDemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!--
https://mvnrepository.com/artifact/org.apache.http
components/httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.5</version></dependency>
</dependencies>
</project>

1.3 编写测试代码

package com.mikey.HttpClient;

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

/**
 * @Program: HttpClient
 * @Author: 麦奇
 * @Email： 1625017540@qq.com
 * @Create: 2019-03-30 17:22
 * @Describe：
 **/
public class HttpClientTest {
    /**
     * Get 请求不带参数
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception{
        //常见一个 HttpClient 对象
        CloseableHttpClient aDefault = HttpClients.createDefault();
        //创建 Get 请求对象。在请求中输入
        HttpGet httpGet = new HttpGet("http://www.baidu.com");
        //发送请求,并返回响应
        CloseableHttpResponse execute = aDefault.execute(httpGet);
        //处理响应
        //获取响应的状态码
        int code=execute.getStatusLine().getStatusCode();

        System.out.println("响应码："+code);

        HttpEntity entity = execute.getEntity();
        //获取响应的内容
        String content = EntityUtils.toString(entity, "utf-8");
        //打印响应内容
        System.out.println("Content:"+content);
        //关闭连接
        aDefault.close();
    }
}

2 发送 GET 请求带参数

/*** Get 请求带参数
* @throws Exception
*/
public static void doGetParam() throws
Exception{
CloseableHttpClient client =
HttpClients.createDefault();
//创建一个封装 URI 的对象。在该对象中可以给定请
求参数
URIBuilder
bui = new
URIBuilder("https://www.sogou.com/web");
bui.addParameter("query", "西游记");
//创建一个 Get 请求对象
HttpGet get = new HttpGet(bui.build());
//发送请求,并返回响应
CloseableHttpResponse res =
client.execute(get);
//处理响应
//获取响应的状态码
int code =
res.getStatusLine().getStatusCode();System.out.println(code);
//获取响应的内容
HttpEntity entity = res.getEntity();
String content =
EntityUtils.toString(entity,"utf-8");
System.out.println(content);
//关闭连接
client.close();
}

3 发送 POST 请求不带参数

/**
* 发送 POST 请求不带参数
*/
public static void doPostTest()throws
Exception{
CloseableHttpClient client =
HttpClients.createDefault();
HttpPost post = new
HttpPost("http://localhost:8080/test/post");
CloseableHttpResponse res =client.execute(post);
//处理响应
//获取响应的状态码
int code =
res.getStatusLine().getStatusCode();
System.out.println(code);
//获取响应的内容
HttpEntity entity = res.getEntity();
String content =
EntityUtils.toString(entity,"utf-8");
System.out.println(content);
//关闭连接
client.close();
}

4 发送 POST 请求带参数

/**
* 发送 POST 请求带参数
*/
public static void doPostParamTest()throws
Exception{CloseableHttpClient client =
HttpClients.createDefault();
HttpPost post = new
HttpPost("http://localhost:8080/test/post/param");
//给定参数
List<BasicNameValuePair> list = new
ArrayList<>();
list.add(new BasicNameValuePair("name", "张
三丰"));
list.add(new BasicNameValuePair("pwd",
"zhangsanfeng"));
//将参数做字符串的转换
StringEntity entity = new
UrlEncodedFormEntity(list,"utf-8");
//向请求中绑定参数
post.setEntity(entity);
//处理响应
CloseableHttpResponse res =
client.execute(post);
//获取响应的状态码
int code =res.getStatusLine().getStatusCode();
System.out.println(code);
//获取响应的内容
HttpEntity en = res.getEntity();
String content =
EntityUtils.toString(en,"utf-8");
System.out.println(content);
//关闭连接
client.close();
}

5 在 POST 请求的参数中传递 JSON 格式数据

/**
* 发送 POST 请求带 JSON 格式参数
*/
public static void doPostParamJsonTest()throws
Exception{
CloseableHttpClient client =
HttpClients.createDefault();
HttpPost post = new
HttpPost("http://localhost:8080/test/post/param/js
on");String json ="{\"name\":\"张三丰
\",\"pwd\":\"zhangsanfeng\"}";
StringEntity entity = new StringEntity(json,
ContentType.APPLICATION_JSON);
//向请求中绑定参数
post.setEntity(entity);
//处理响应
CloseableHttpResponse res =
client.execute(post);
//获取响应的状态码
int code =
res.getStatusLine().getStatusCode();
System.out.println(code);
//获取响应的内容
HttpEntity en = res.getEntity();
String content =
EntityUtils.toString(en,"utf-8");
System.out.println(content);
//关闭连接
client.close();
}

6 HttpClient 自定义工具类的使用
6.1 编写工具类

public class HttpClientUtil {
public static String doGet(String url,
Map<String, String> param) {
// 创建 Httpclient 对象
CloseableHttpClient httpclient =
HttpClients.createDefault();
String resultString = "";
CloseableHttpResponse response = null;
try {
// 创建 uri
URIBuilder builder = new URIBuilder(url);
if (param != null) {
for (String key : param.keySet()) {
builder.addParameter(key,
param.get(key));
}}
URI uri = builder.build();
// 创建 http GET 请求
HttpGet httpGet = new HttpGet(uri);
// 执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为 200
if
(response.getStatusLine().getStatusCode() == 200) {
resultString =
EntityUtils.toString(response.getEntity(),
"UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
public static String doGet(String url) {
return doGet(url, null);
}
public static String doPost(String url,
Map<String, String> param) {
// 创建 Httpclient 对象
CloseableHttpClient httpClient =
HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建 Http Post 请求
HttpPost httpPost = new HttpPost(url);// 创建参数列表
if (param != null) {
List<NameValuePair> paramList = new
ArrayList<>();
for (String key : param.keySet()) {
paramList.add(new
BasicNameValuePair(key, param.get(key)));
}
// 模拟表单
UrlEncodedFormEntity entity = new
UrlEncodedFormEntity(paramList,"utf-8");
httpPost.setEntity(entity);
}
// 执行 http 请求
response = httpClient.execute(httpPost);
resultString =
EntityUtils.toString(response.getEntity(),
"utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultString;
}
public static String doPost(String url) {
return doPost(url, null);
}
public static String doPostJson(String url,
String json) {
// 创建 Httpclient 对象
CloseableHttpClient httpClient =
HttpClients.createDefault();
CloseableHttpResponse response = null;
String resultString = "";
try {// 创建 Http Post 请求
HttpPost httpPost = new HttpPost(url);
// 创建请求内容
StringEntity entity = new
StringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 执行 http 请求
response = httpClient.execute(httpPost);
resultString =
EntityUtils.toString(response.getEntity(),
"utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}return resultString;
}
}

6.2 测试工具类

/**
* 测试 HttpClient 工具类
*/
public static void httpClientUtilTest(){
String url =
"http://localhost:8080/test/post/param";
Map<String, String> param = new HashMap<>();
param.put("name", "李四");
param.put("pwd", "lisi");
String result = HttpClientUtil.doPost(url,
param);
System.out.println(result);
}

实战案例

1 需求
1) 采用 SOA 架构项目2) 使用 HttpClient 调用服务
3) 完成用户的添加与查询
2 项目架构
3 表结构

CREATE TABLE `users` (
`userid` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(30) DEFAULT NULL,
`userage` int(11) DEFAULT NULL,
PRIMARY KEY (`userid`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

4 创建项目
4.1 创建 commons 项目
4.1.1 创建项目
4.1.2 需改 POM 文件

<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instan
ce"xsi:schemaLocation="http://maven.apache.org/P
OM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.bjsxt</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>com.bjsxt</groupId>
<artifactId>commons</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!-- Jackson Json 处理工具包 -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
</dependency>
<dependency><groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.5</version>
</dependency>
</dependencies>
</project>

4.2 创建 service 项目
4.2.1 创建项目4.2.2 修改 POM 文件

<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instan
ce"
xsi:schemaLocation="http://maven.apache.org/P
OM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.bjsxt</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>com.bjsxt</groupId>
<artifactId>service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>com.bjsxt</groupId><artifactId>commons</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<!-- 单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<!-- 日志处理 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</dependency>
<!-- Mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId>
</dependency>
<!-- MySql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- 连接池 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
</dependency>
<!-- Spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency><groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
</dependency>
<dependency>
<groupId>javax.servlet</groupId><artifactId>servlet-api</artifactId>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
</resource>
</resources><!-- tomcat 插件,由于子项目不一定每个都是 web
项目,所以该插件只是声明,并未开启 -->
<plugins>
<!-- 配置 Tomcat 插件 -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<configuration>
<path>/</path>
<port>8080</port>
</configuration>
</plugin>
</plugins>
</build>
</project>

4.3 创建 client 项目
4.3.1 创建项目
4.3.2 修改 POM 文件

<project
xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instan
ce"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.bjsxt</groupId>
<artifactId>parent</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>com.bjsxt</groupId>
<artifactId>client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>com.bjsxt</groupId>
<artifactId>commons</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<!-- 单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency><!-- 日志处理 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</dependency>
<!-- Spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jsp-api</artifactId>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<!-- tomcat 插件,由于子项目不一定每个都是 web
项目,所以该插件只是声明,并未开启 --><plugins>
<!-- 配置 Tomcat 插件 -->
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<configuration>
<path>/</path>
<port>8081</port>
</configuration>
</plugin>
</plugins>
</build>
</project>

5 添加用户
5.1 Client
5.1.1 addUser.jsp

<%@ page language="java" contentType="text/html;
charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01
Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/user/addUser" method="post">
用户姓名:<input type="text"
name="username"/><br/>
用户年龄:<input type="text"
name="userage"/><br/>
<input type="submit" value="OKOK"/>
</form>
</body>
</html>

5.1.2 UserService

@Override
public void addUser(Users user) {
String json = JsonUtils.objectToJson(user);
String code =
HttpClientUtil.doPostJson("http://localhost:8080/u
ser/insertUser", json);
Map<String, Integer> map =
JsonUtils.jsonToPojo(code, Map.class);
Integer var = map.get("code");
if(var == 500){
System.out.println("出错了");
}else{
System.out.println("添加成功");
}
}

5.1.3 UserController

@Controller
@RequestMapping("/user")
public class UserController {@Autowired
private UserService userService;
/**
* 添加用户
*/
@RequestMapping("/addUser")
public String addUser(Users user){
this.userService.addUser(user);
return "ok";
}
}
5.2 Service
5.2.1 UserController
@Controller
@RequestMapping("/user")
public class UserController {
@Autowiredprivate UserService userService;
@RequestMapping("/insertUser")
@ResponseBody
public Object insertUser(@RequestBody Users
user){
Map<String, Integer> map = new HashMap<>();
try{
this.userService.insertUser(user);
map.put("code", 200);
}catch(Exception e){
e.printStackTrace();
map.put("code", 500);
}
return map;
}
}

5.2.2 UserService

@Service
public class UserServiceImpl implementsUserService {
@Autowired
private UserMapper userMapper;
@Override
public void insertUser(Users user) {
this.userMapper.insertUser(user);
}
}

6 查询用户
6.1 Client
6.1.1 UserController

/**
* 查询全部用户
*/
@RequestMapping("/findUser")
public String findUserAll(Model model){
List<Users> list =
this.userService.findUserAll();model.addAttribute("list", list);
return "showUser";
}
6.1.2 UserService
@Override
public List<Users> findUserAll() {
String var =
HttpClientUtil.doPost("http://localhost:8080/user/
selectUserAll");
List<Users> list = JsonUtils.jsonToList(var,
Users.class);
return list;
}

6.2 Service
6.2.1 UserController

@RequestMapping("/selectUserAll")
@ResponseBody
public Object selectUserAll(){
return this.userService.selectUserAll();
}6.2.2 UserService
@Override
public List<Users> selectUserAll() {
return this.userMapper.selectUserAll();
}