HttpClient、FastJson將json轉換為JavaBean

HttpClient

一、HttpClient簡介

????HttpClient 是Apache Jakarta Common 下的子項目，可以用來提供高效的、最新的、功能豐富的支持 HTTP 協議的客戶端編程工具包，并且它支持 HTTP 協議最新的版本和建議。
????HTTP 協議可能是現在 Internet 上使用得最多、最重要的協議了，越來越多的 Java 應用程序需要直接通過 HTTP 協議來訪問網絡資源。雖然在 JDK 的 java net包中已經提供了訪問 HTTP 協議的基本功能，但是對于大部分應用程序來說，JDK 庫本身提供的功能還不夠豐富和靈活。HttpClient 是 Apache Jakarta Common 下的子項目，用來提供高效的、最新的、功能豐富的支持 HTTP 協議的客戶端編程工具包，并且它支持 HTTP 協議最新的版本和建議。HttpClient 已經應用在很多的項目中，比如 Apache Jakarta 上很著名的另外兩個開源項目 Cactus 和 HTMLUnit 都使用了 HttpClient。

二、FastJson

1、FastJson簡介

Fastjson 是一個 Java 庫，可以將 Java 對象轉換為 JSON 格式，當然它也可以將 JSON 字符串轉換為 Java 對象。

Fastjson 可以操作任何 Java 對象，即使是一些預先存在的沒有源碼的對象。

Fastjson 源碼地址：https://github.com/alibaba/fastjson

Fastjson 中文 Wiki：https://github.com/alibaba/fastjson/wiki/Quick-Start-CN

FastJson特性

提供服務器端、安卓客戶端兩種解析工具，性能表現較好。

提供了 toJSONString() 和 parseObject() 方法來將 Java 對象與 JSON 相互轉換。調用toJSONString方 法即可將對象轉換成 JSON 字符串，parseObject 方法則反過來將 JSON 字符串轉換成對象。

允許轉換預先存在的無法修改的對象（只有class、無源代碼）。

Java泛型的廣泛支持。

允許對象的自定義表示、允許自定義序列化類。

支持任意復雜對象（具有深厚的繼承層次和廣泛使用的泛型類型）。

例子

1、GetData.java：使用httpclient接收數據、再用fastJson將json數據解析為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();

        //創建get請求實例
        //HttpGet get = new HttpGet("http://www.baidu.com");
        HttpGet get = new HttpGet("http://localhost:7333/a");
        System.out.println("請求的uri為:"+get.getURI());

        try {
            // 客戶端執行get請求 返回響應實體
            HttpResponse response = client.execute(get);

            //獲取請求狀態行
            System.out.println("請求狀態行為:"+response.getStatusLine());

            //獲取所有的請求頭
            Header[] headers=response.getAllHeaders();

            for (Header header :headers){
            //遍歷獲取所有請求頭的名稱和值
            System.out.println(header.getName()+" :--: "+header.getValue());
            }
            System.out.println("-----------------------------------------------");
            //獲取響應的實體
            HttpEntity entity =response.getEntity();

            if (entity!=null){
            String str=EntityUtils.toString(entity,"UTF-8");
            System.out.println("entity:"+str);
            System.out.println("獲取到的json為："+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("內容長度為:"+entity.getContentLength());
        }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            //釋放連接
            client.getConnectionManager().shutdown();
        }
    }
}

2、http://localhost:7333/a返回的json數據

{
    "name":"James",
    "age":18,
    "address":"chongqing"
}

3、User.java實體類

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、

輸出結果：

請求的uri為: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
請求狀態行為: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"}
獲取到的json為：{"name":"James","age":18,"address":"chongqing"}
User: User{name='James', age=18, address='chongqing'}
newUser.getAddress(): chongqing
=================================
內容長度為:-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

Process finished with exit code 0