前言：因公司项目的需求，需要调用外部系统接口。参考了论坛上的各个文章。决定自己写个笔记，以便更好的学习，记录。

废话不多说：

需要的jar包

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

代码

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.message.BasicNameValuePair;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;


/**
 * Created by hshibao01 on 2016/12/28.
 */
public class HttpClientUtils {

    private String charsert = "UTF-8";

    private List params = new ArrayList();

    private String url;

    private HttpClient httpClient;

    public HttpClientUtils setCharsert(String charsert) {
        this.charsert = charsert;
        return this;
    }

    public HttpClientUtils setParam(String name, String value) {
        this.params.add(new BasicNameValuePair(name, value));
        return this;
    }

    public HttpClientUtils setParam(Map<String, String> params) {
        for (Map.Entry<String, String> entry : params.entrySet()) {
            this.params.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
        }
        return this;
    }

    public HttpClientUtils() {
        httpClient = HttpClientBuilder.create().build();
    }

    public HttpClient getHttpClient() {
        return httpClient;
    }

    public HttpClientUtils setUrl(String url) {
        this.url = url;
        return this;
    }

    public String post() {
        if (params != null) {
            url = url + "?" + URLEncodedUtils.format(this.params, this.charsert);
            System.out.println(url);
        }
        HttpPost httpPost = new HttpPost(url);
        try {
            HttpResponse httpResponse = this.getHttpClient().execute(httpPost);
            //连接成功
            if (200 == httpResponse.getStatusLine().getStatusCode()) {
                HttpEntity httpEntity = httpResponse.getEntity();
                return convertStreamToString(httpEntity.getContent(), this.charsert);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public String get() {
        if (params != null) {
            url = url + "?" + URLEncodedUtils.format(this.params, this.charsert);
            System.out.println(url);
        }
        HttpGet httpGet = new HttpGet(url);
        try {
            HttpResponse httpResponse = this.getHttpClient().execute(httpGet);
            //连接成功
            if (200 == httpResponse.getStatusLine().getStatusCode()) {
                HttpEntity httpEntity = httpResponse.getEntity();
                return convertStreamToString(httpEntity.getContent(), this.charsert);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String convertStreamToString(InputStream is, String charset) {
        StringBuilder sb1 = new StringBuilder();
        byte[] bytes = new byte[4096];
        int size = 0;

        try {
            while ((size = is.read(bytes)) > 0) {
                String str = new String(bytes, 0, size, charset);
                sb1.append(str);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb1.toString();
    }

    public static void main(String[] args) {
        HttpClientUtils httpClientUtils = new HttpClientUtils();
        String retu = httpClientUtils.setUrl("http://192.168.10.65:7979/erp/t")
                .setParam("param", "中文")
                .setCharsert("UTF-8").get();
        System.out.println(retu);
    }
}

由于项目只是简单的涉及到get post请求， 暂时未完善， 后期会根据情况进行修改，若有不足之处望谅解。