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。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 协议最新的版本和建议。HttpClient 已经应用在很多的项目中，比如 Apache Jakarta 上很著名的另外两个开源项目 Cactus 和 HTMLUnit 都使用了 HttpClient。
Fastjson 是一个 Java 库，可以将 Java 对象转换为 JSON 格式，当然它也可以将 JSON 字符串转换为 Java 对象。
Fastjson 可以操作任何 Java 对象，即使是一些预先存在的没有源码的对象。
Fastjson 源码地址：https://github.com/alibaba/fastjson
Fastjson 中文 Wiki：https://github.com/alibaba/fastjson/wiki/Quick-Start-CN
提供服务器端、安卓客户端两种解析工具，性能表现较好。
提供了 toJSONString() 和 parseObject() 方法来将 Java 对象与 JSON 相互转换。调用toJSONString方 法即可将对象转换成 JSON 字符串，parseObject 方法则反过来将 JSON 字符串转换成对象。
允许转换预先存在的无法修改的对象（只有class、无源代码）。
Java泛型的广泛支持。
允许对象的自定义表示、允许自定义序列化类。
支持任意复杂对象（具有深厚的继承层次和广泛使用的泛型类型）。
1、GetData.java：使用httpclient接收数据、再用fastJson将json数据解析为JavaBean。
package com.get_data.get;
import java.io.IOException;
import com.alibaba.fastjson.JSON;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
public class GetData {
public static void main(String[] args) {
HttpClient client = new DefaultHttpClient();
//创建get请求实例
//HttpGet get = new HttpGet("http://www.baidu.com");
HttpGet get = new HttpGet("http://localhost:7333/a");
System.out.println("请求的uri为:"+get.getURI());
try {
// 客户端执行get请求 返回响应实体
HttpResponse response = client.execute(get);
//获取请求状态行
System.out.println("请求状态行为:"+response.getStatusLine());
//获取所有的请求头
Header[] headers=response.getAllHeaders();
for (Header header :headers){
//遍历获取所有请求头的名称和值
System.out.println(header.getName()+" :--: "+header.getValue());
}
System.out.println("-----------------------------------------------");
//获取响应的实体
HttpEntity entity =response.getEntity();
if (entity!=null){
String str=EntityUtils.toString(entity,"UTF-8");
System.out.println("entity:"+str);
System.out.println("获取到的json为："+str);
User newUser = JSON.parseObject(str, User.class);
System.out.println("User: "+newUser);
System.out.println("newUser.getAddress(): "+newUser.getAddress());
//System.out.println(EntityUtils.toString(entity,"UTF-8"));
System.out.println("=================================");
System.out.println("内容长度为:"+entity.getContentLength());
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally{
//释放连接
client.getConnectionManager().shutdown();
}
}
}2、http://localhost:7333/a返回的json数据
{
"name":"James",
"age":18,
"address":"chongqing"
}3、User.java实体类
public class User {
private String name;
private int age;
private String sex;
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
private String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"name='" + name + '\'' +
", age=" + age +
", address='" + address + '\'' +
'}';
}
}4、
输出结果：
请求的uri为:http://localhost:7333/a
14:31:04.341 [main] DEBUG org.apache.http.impl.conn.BasicClientConnectionManager - Get connection for route {}->http://localhost:7333
14:31:04.387 [main] DEBUG org.apache.http.impl.conn.DefaultClientConnectionOperator - Connecting to localhost:7333
14:31:04.403 [main] DEBUG org.apache.http.client.protocol.RequestAddCookies - CookieSpec selected: default
14:31:04.403 [main] DEBUG org.apache.http.client.protocol.RequestAuthCache - Auth cache not set in the context
14:31:04.403 [main] DEBUG org.apache.http.client.protocol.RequestTargetAuthentication - Target auth state: UNCHALLENGED
14:31:04.403 [main] DEBUG org.apache.http.client.protocol.RequestProxyAuthentication - Proxy auth state: UNCHALLENGED
14:31:04.403 [main] DEBUG org.apache.http.impl.client.DefaultHttpClient - Attempt 1 to execute request
14:31:04.403 [main] DEBUG org.apache.http.impl.conn.DefaultClientConnection - Sending request: GET /a HTTP/1.1
14:31:04.403 [main] DEBUG org.apache.http.wire - >> "GET /a HTTP/1.1[\r][\n]"
14:31:04.403 [main] DEBUG org.apache.http.wire - >> "Host: localhost:7333[\r][\n]"
14:31:04.403 [main] DEBUG org.apache.http.wire - >> "Connection: Keep-Alive[\r][\n]"
14:31:04.403 [main] DEBUG org.apache.http.wire - >> "User-Agent: Apache-HttpClient/4.5.2 (Java/1.8.0_161)[\r][\n]"
14:31:04.403 [main] DEBUG org.apache.http.wire - >> "[\r][\n]"
14:31:04.403 [main] DEBUG org.apache.http.headers - >> GET /a HTTP/1.1
14:31:04.403 [main] DEBUG org.apache.http.headers - >> Host: localhost:7333
14:31:04.403 [main] DEBUG org.apache.http.headers - >> Connection: Keep-Alive
14:31:04.403 [main] DEBUG org.apache.http.headers - >> User-Agent: Apache-HttpClient/4.5.2 (Java/1.8.0_161)
14:31:04.419 [main] DEBUG org.apache.http.wire - << "HTTP/1.1 200 [\r][\n]"
14:31:04.434 [main] DEBUG org.apache.http.wire - << "Content-Type: application/json;charset=UTF-8[\r][\n]"
14:31:04.434 [main] DEBUG org.apache.http.wire - << "Transfer-Encoding: chunked[\r][\n]"
14:31:04.434 [main] DEBUG org.apache.http.wire - << "Date: Tue, 01 Jan 2019 06:31:04 GMT[\r][\n]"
14:31:04.434 [main] DEBUG org.apache.http.wire - << "[\r][\n]"
14:31:04.434 [main] DEBUG org.apache.http.impl.conn.DefaultClientConnection - Receiving response: HTTP/1.1 200
14:31:04.434 [main] DEBUG org.apache.http.headers - << HTTP/1.1 200
14:31:04.434 [main] DEBUG org.apache.http.headers - << Content-Type: application/json;charset=UTF-8
14:31:04.434 [main] DEBUG org.apache.http.headers - << Transfer-Encoding: chunked
14:31:04.434 [main] DEBUG org.apache.http.headers - << Date: Tue, 01 Jan 2019 06:31:04 GMT
14:31:04.434 [main] DEBUG org.apache.http.impl.client.DefaultHttpClient - Connection can be kept alive indefinitely
请求状态行为:HTTP/1.1 200
Content-Type :--: application/json;charset=UTF-8
Transfer-Encoding :--: chunked
Date :--: Tue, 01 Jan 2019 06:31:04 GMT
-----------------------------------------------
14:31:04.450 [main] DEBUG org.apache.http.wire - << "2f[\r][\n]"
14:31:04.450 [main] DEBUG org.apache.http.wire - << "{"name":"James","age":18,"address":"chongqing"}"
14:31:04.450 [main] DEBUG org.apache.http.wire - << "[\r][\n]"
14:31:04.450 [main] DEBUG org.apache.http.wire - << "0[\r][\n]"
14:31:04.450 [main] DEBUG org.apache.http.wire - << "[\r][\n]"
14:31:04.450 [main] DEBUG org.apache.http.impl.conn.BasicClientConnectionManager - Releasing connection org.apache.http.impl.conn.ManagedClientConnectionImpl@4d3167f4
14:31:04.450 [main] DEBUG org.apache.http.impl.conn.BasicClientConnectionManager - Connection can be kept alive indefinitely
entity:{"name":"James","age":18,"address":"chongqing"}
获取到的json为：{"name":"James","age":18,"address":"chongqing"}
User: User{name='James', age=18, address='chongqing'}
newUser.getAddress(): chongqing
=================================
内容长度为:-1
14:31:04.590 [main] DEBUG org.apache.http.impl.conn.DefaultClientConnection - Connection 0.0.0.0:64518<->127.0.0.1:7333 closed
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