HttpClient学习笔记

作者: 青年心路 | 来源:发表于2019-08-03 19:20 被阅读0次

一、HttpClient简介

HttpClient是Apache Jakarta Common下的子项目，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协议最新版本和建议。
HTTP协议可能是Internet中使用最多、最重要的协议了，越来越多的Java应用程序需要使用HTTP协议。虽然JDK的java.net包中已经提供了访问HTTP协议的基本功能，但是功能还不是很强大。

二、HttpClient的应用

1.发送Get请求不带参数

1.1 创建项目

httpClientDemo

1.2 添加依赖

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
</dependency>

1.3 编写测试代码

    @Test
    public void doGet() throws IOException {
        //创建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
        //获取响应状态码
        int code = res.getStatusLine().getStatusCode();
        System.out.println(code);

        //获取响应内容
        HttpEntity entity = res.getEntity();
        String str = EntityUtils.toString(entity, "UTF-8");
        System.out.println(str);

        //关闭client
        client.close();
    }

2.发送Get请求带参数

    @Test
    public void doGetParam() throws URISyntaxException, IOException {
        CloseableHttpClient client = HttpClients.createDefault();
        //创建封装URI的对象，在该对象中可以给定参数
        URIBuilder builder = new URIBuilder("https://www.sogou.com/web");
        builder.addParameter("query", "西游记");
        //创建Get请求对象
        HttpGet get = new HttpGet(builder.build());

        //发送请求并返回响应
        CloseableHttpResponse res = client.execute(get);

        //处理响应
        //获取响应状态码
        int code = res.getStatusLine().getStatusCode();
        System.out.println(code);

        //获取响应内容
        HttpEntity entity = res.getEntity();
        String str = EntityUtils.toString(entity, "UTF-8");
        System.out.println(str);

        //关闭client
        client.close();
    }

3.发送Post请求不带参数

    @Test
    public void doPost() throws IOException {
        CloseableHttpClient client = HttpClients.createDefault();
        HttpPost post = new HttpPost("http://localhost:8080/test/post");
        CloseableHttpResponse res = client.execute(post);

        int code = res.getStatusLine().getStatusCode();
        System.out.println(code);

        HttpEntity entity = res.getEntity();
        String str = EntityUtils.toString(entity);
        System.out.println(str);

        client.close();
    }

4.发送Post请求带参数

    @Test
    public void doPostParam() throws IOException {
        CloseableHttpClient client = HttpClients.createDefault();
        HttpPost post = new HttpPost("http://localhost:8080/test/postParam");

        //给定参数
        List<BasicNameValuePair> list = new ArrayList<>();
        list.add(new BasicNameValuePair("name", "张三丰"));
        list.add(new BasicNameValuePair("pwd", "123"));

        //将给定的参数转换成字符串，通过http数据包传递过去（需要指定编码，默认使用GBK编码）
        StringEntity se = new UrlEncodedFormEntity(list,"UTF-8");
        //向请求中绑定参数
        post.setEntity(se);

        CloseableHttpResponse res = client.execute(post);

        int code = res.getStatusLine().getStatusCode();
        System.out.println(code);

        HttpEntity entity = res.getEntity();
        String str = EntityUtils.toString(entity);
        System.out.println(str);

        client.close();
    }

5.在Post请求参数中传递Json格式数据

    @Test
    public void doPostParamJson() throws IOException {
        CloseableHttpClient client = HttpClients.createDefault();
        HttpPost post = new HttpPost("http://localhost:8080/test/postParamJson");
        String json = "{\"name\":\"张三丰\",\"pwd\":\"123\"}";
        StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
        //数据绑定
        post.setEntity(entity);

        //处理响应
        CloseableHttpResponse res = client.execute(post);

        int code = res.getStatusLine().getStatusCode();
        System.out.println(code);

        HttpEntity httpEntity = res.getEntity();
        String str = EntityUtils.toString(httpEntity, "UTF-8");
        System.out.println(str);

        client.close();
    }

6.编写HttpClient的工具类

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) {
                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) {
                e.printStackTrace();
            }
        }

        return resultString;
    }
}

7.测试HtppClientUtil

    @Test
    public void httpClientUtilTest(){
        String url = "http://localhost:8080/test/postParam";
        Map<String, String> map = new HashMap<>();
        map.put("name", "alice");
        map.put("pwd", "123");
        String str = HttpClientUtil.doPost(url, map);
        System.out.println(str);
    }

三、实战案例

1.需求：

采用SOA架构项目
使用HttpClient调用服务
完成用户的添加和查询

2.项目架构

image.png

3.创建表

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 项目名称

commons

4.2 添加依赖

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </dependency>
    </dependencies>

4.3 项目名称

service

4.4 添加依赖

<?xml version="1.0" encoding="UTF-8"?>

<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">
    <parent>
        <artifactId>httpClientParent</artifactId>
        <groupId>com.hxx</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>service</artifactId>
    <packaging>war</packaging>

    <name>service Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>

        <dependency>
            <groupId>com.hxx</groupId>
            <artifactId>commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!--日志-->
        <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-beans</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</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>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
        </dependency>

        <!--javaee-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
        </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>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <configuration>
                    <path>/</path>
                    <port>9090</port>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

4.5 项目名称

client

4.6 添加依赖

<?xml version="1.0" encoding="UTF-8"?>

<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">
    <parent>
        <artifactId>httpClientParent</artifactId>
        <groupId>com.hxx</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>client</artifactId>
    <packaging>war</packaging>

    <name>client Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>

        <dependency>
            <groupId>com.hxx</groupId>
            <artifactId>commons</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!--日志-->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </dependency>

        <!--spring-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
        </dependency>

        <!--javaee-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jsp-api</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </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>
                </includes>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <configuration>
                    <path>/</path>
                    <port>9091</port>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

5.添加用户

略

6.查询用户

略

HttpClient学习笔记

一、HttpClient简介

二、HttpClient的应用

1.发送Get请求不带参数

1.1 创建项目

1.2 添加依赖

1.3 编写测试代码

2.发送Get请求带参数

3.发送Post请求不带参数

4.发送Post请求带参数

5.在Post请求参数中传递Json格式数据

6.编写HttpClient的工具类

7.测试HtppClientUtil

三、实战案例

1.需求：

2.项目架构

3.创建表

4.创建项目

4.1 项目名称

4.2 添加依赖

4.3 项目名称

4.4 添加依赖

4.5 项目名称

4.6 添加依赖

5.添加用户

6.查询用户

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