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1.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。
HttpClient 提供的主要的功能
（1）实现了所有 HTTP 的方法（GET,POST,PUT,DELETE等）
（2）支持自动转向
（3）支持 HTTPS 协议
（4）支持代理服务器等
2.httpClient使用
httpClient可以模拟用户使用浏览器
2.1导包
我这里使用的是maven，也可以直接下载httpclient的jar包
<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.test</groupId>
<artifactId>httpclient</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.5</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- java编译插件 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>2.2模拟GET请求
也可以在url后面加上参数。
package com.test.httpclient;
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;
public class DoGET {
public static void main(String[] args) throws Exception {
// 1.创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
// 2.创建http GET请求
HttpGet httpGet = new HttpGet("http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html");
CloseableHttpResponse response = null;
try {
// 3.执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
String content = EntityUtils.toString(response.getEntity(), "UTF-8");
System.out.println("内容长度：" + content.length());
System.out.println(content);//响应的内容
}
} finally {
if (response != null) {
response.close();
}
httpclient.close();
}
}
}
2.2模拟有参数GET请求
package com.httpclient.test;
import java.net.URI;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class DoGETParam {
public static void main(String[] args) throws Exception {
// 1.创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
// 2.定义请求的参数
URI uri = new URIBuilder("http://localhost:8081/item/list").setParameter("page", "3").setParameter("rows", "10")
.build();
// 3.创建http GET请求
HttpGet httpGet = new HttpGet(uri);
CloseableHttpResponse response = null;
try {
//4. 执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
String content = EntityUtils.toString(response.getEntity(), "UTF-8");
System.out.println(content);
}
} finally {
if (response != null) {
response.close();
}
httpclient.close();
}
}
}
设置参数有两种方法
第一种addParameter，即使参数名一样也会被提交过去，可以提交表单中type="checkbox"，多选按钮。
//new URIBuilder("http://localhost:8081/item/list").addParameter("a", "1").addParameter("a", "2");
//http://localhost:8081/item/list?a=1&a=2
第二种addParameter，参数名一样会被覆盖
//new URIBuilder("http://localhost:8081/item/list").setParameter("a", "1").setParameter("a", "2");
//http://localhost:8081/item/list?a=22.3模拟POST请求
package com.httpclient.test;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class DoPOST {
public static void main(String[] args) throws Exception {
// 1.创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
// 2.创建http POST请求
HttpPost httpPost = new HttpPost("https://baike.baidu.com/item/%E4%BD%A0%E5%A5%BD/32416?fr=aladdin");
// 3.设置user-agent
//httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36");
CloseableHttpResponse response = null;
try {
// 4.执行请求
response = httpclient.execute(httpPost);
System.out.println(response.getStatusLine().getStatusCode());
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
String content = EntityUtils.toString(response.getEntity(), "UTF-8");
System.out.println(content);
}
} finally {
if (response != null) {
response.close();
}
httpclient.close();
}
}
}
2.4模拟有参数POST
package com.httpclient.test;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
public class DoPOSTParam {
public static void main(String[] args) throws Exception {
// 1.创建Httpclient对象
CloseableHttpClient httpclient = HttpClients.createDefault();
// 2.创建http POST请求
HttpPost httpPost = new HttpPost("xxxxxxxxxx");
// 3.设置2个post参数，一个是scope、一个是q
List<NameValuePair> parameters = new ArrayList<NameValuePair>(0);
parameters.add(new BasicNameValuePair("username", "xxxxx"));
parameters.add(new BasicNameValuePair("password", "xxxxx"));
// 4.构造一个form表单式的实体
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
// 5.将请求实体设置到httpPost对象中
httpPost.setEntity(formEntity);
httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36");
CloseableHttpResponse response = null;
try {
// 6.执行请求
response = httpclient.execute(httpPost);
System.out.println(response.getStatusLine().getStatusCode());
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
String content = EntityUtils.toString(response.getEntity(), "UTF-8");
System.out.println(content);
}
} finally {
if (response != null) {
response.close();
}
httpclient.close();
}
}
}