喵星之旅-狂奔的兔子-使用java实现http请求（无需登录）

一、获取jar

实现任何功能肯定是先获取相应工具类，即jar包。可以使用复制的方式或者maven获取。项目中已导入jar，可以直接使用。

需要的jar入图：

项目地址：svn://47.105.188.20/kitty/2%E3%80%81code/httpdemo   用户名密码：reader/reader

maven地址：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.2</version>
</dependency>

<!--fastjson-->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.32</version>
</dependency>

二、编写工具类

package club.kittybunny.httpclient;

import java.util.HashMap;
import java.util.Map;

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import com.alibaba.fastjson.JSON;
/**
 * 除了使用项目提供的jar也可以使用maven下载，参考地址如下
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.2</version>
</dependency>

<!--fastjson-->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.32</version>
</dependency>

 * @author bunny～～我是兔子我会喵，我叫喵星兔。
 *
 */
public class HttpUtil {
    /** 请求编码 */
    private static final String DEFAULT_CHARSET = "UTF-8";

    /**
     * 执行HTTP POST请求
     * 
     * @param url
     *            url
     * @param param
     *            参数
     * @return
     */
    public static String httpPostWithJSON(String url, Map<String, ?> param) {
        CloseableHttpClient client = null;
        try {
            if (url == null || url.trim().length() == 0) {
                throw new Exception("URL is null");
            }
            HttpPost httpPost = new HttpPost(url);
            client = HttpClients.createDefault();
            if (param != null) {
                StringEntity entity = new StringEntity(JSON.toJSONString(param), DEFAULT_CHARSET);// 解决中文乱码问题
                entity.setContentEncoding(DEFAULT_CHARSET);
                entity.setContentType("application/json");
                httpPost.setEntity(entity);
            }
            HttpResponse resp = client.execute(httpPost);
            if (resp.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(resp.getEntity(), DEFAULT_CHARSET);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            close(client);
        }
        return null;
    }

    /**
     * 执行HTTP GET请求
     * 
     * @param url
     *            url
     * @param param
     *            参数
     * @return
     */
    public static String httpGetWithJSON(String url, Map<String, ?> param) {
        CloseableHttpClient client = null;
        try {
            if (url == null || url.trim().length() == 0) {
                throw new Exception("URL is null");
            }
            client = HttpClients.createDefault();
            if (param != null) {
                StringBuffer sb = new StringBuffer("?");
                for (String key : param.keySet()) {
                    sb.append(key).append("=").append(param.get(key)).append("&");
                }
                url = url.concat(sb.toString());
                url = url.substring(0, url.length() - 1);
            }
            
            HttpGet httpGet = new HttpGet(url);
            HttpResponse resp = client.execute(httpGet);
            if (resp.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(resp.getEntity(), DEFAULT_CHARSET);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            close(client);
        }
        return null;
    }

    /**
     * 关闭HTTP请求
     * 
     * @param client
     */
    private static void close(CloseableHttpClient client) {
        if (client == null) {
            return;
        }
        try {
            client.close();
        } catch (Exception e) {
        }
    }
    
}

三、编写测试类

    public static void main(String[] args) {
        Map<String, String> param = new HashMap<>();
        param.put("name", "hehe");


        String result = httpGetWithJSON("http://127.0.0.1:9999/hello", param);
        System.out.println("result:" + result);
    }

执行结果如下：