HttpClient

一、 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-instance"
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>
 <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

 

public class HttpClientTest {
public static void main(String[] args) throws
Exception {
HttpClientTest.doGet();
}
/**
* Get 请求不带参数
* @throws Exception 
* @throws ClientProtocolException 
*/
public static void doGet() throws Exception{
//常见一个 HttpClient 对象
CloseableHttpClient client = 
HttpClients.createDefault();
//创建 Get 请求对象。在请求中输入 url
HttpGet get = new
HttpGet("http://www.baidu.com");
//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();
} }

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);
}

三、 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

5.1Client

5.1.1addUser.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>

5.1.2UserService

@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");
} }

5.1.3UserController

@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"; } }

5.2Service

5.2.1UserController

@Controller
@RequestMapping("/user")
public class UserController {
@Autowired
private 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; } }

5.2.2UserService

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

6 查询用户

6.1Client

6.1.1UserController

/**
* 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"; }

6.1.2UserService

@Override
public List<Users> findUserAll() {
String var = 
HttpClientUtil.doPost("http://localhost:8080/user/
selectUserAll");
List<Users> list = JsonUtils.jsonToList(var, 
Users.class);
return list; }

6.2Service

6.2.1UserController

@RequestMapping("/selectUserAll") @ResponseBody
public Object selectUserAll(){
return this.userService.selectUserAll();
}

6.2.2UserService

@Override
public List<Users> selectUserAll() {
return this.userMapper.selectUserAll();
}