远程调用-001、HttpClient

一、调用者

1、创建JavaWeb工程

2、创建lib目录，并引入相应的jar包

# 创建lib目录：web/WEB-INF/lib，并引入如下jar包
httpclient-4.5.2.jar
lombok-1.18.20.jar
commons-lang-2.3.jar
commons-logging-1.1.1.jar

3、创建config.properties文件

# 路径：web/WEB-INF/config/config.properties，内容如下
test.query=http://localhost:8091/test/query
test.test=http://localhost:8091/test/test

4、修改端口号

5、创建工具类

（1）创建HttpClient的工具类

public class HttpUtil {

    /*httpClient的post请求*/
    public String post(String url,Map map){
        String result=null;
        // 创建 HttpClient 客户端
        CloseableHttpClient httpClient = HttpClients.createDefault();

        // 创建 HttpPost 请求
        HttpPost httpPost = new HttpPost(url);

        String json = JSON.toJSONString(map);

        CloseableHttpResponse httpResponse = null;

        try {
            httpPost.addHeader("Content-type","application/json;chartset=utf-8");
            httpPost.setHeader("Accept","application/json");
            // 创建请求内容
            StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
            httpPost.setEntity(entity);

            httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            // 输出请求结果
            result=EntityUtils.toString(httpEntity,Charset.forName("utf-8"));

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 无论如何必须关闭连接
        finally {
            try {
                if (httpResponse != null) {
                    httpResponse.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                if (httpClient != null) {
                    httpClient.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return result;
    }
    
    /*httpClient的get请求*/
    public String get(String url,List<NameValuePair> list){
        String result=null;
        CloseableHttpClient httpclient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        try {
            URIBuilder uriBuilder = new URIBuilder(url);
            uriBuilder.setParameters(list);
            HttpGet httpGet = new HttpGet(uriBuilder.build());

            // 执行http get请求
            response = httpclient.execute(httpGet);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                result = EntityUtils.toString(response.getEntity(), Charset.forName("utf-8"));
            }
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                if (response != null) {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }
}

（2）创建动态获取config.properties上参数的工具类

package com.liws.test.tool;

public class ReadConfigFileInfo {

    public  String getValFromConfig(String key){
        try{
            String url = this.getClass().getResource("").getPath().replaceAll("%20", " ");
            String path = url.substring(0, url.indexOf("WEB-INF")) + "WEB-INF/config/config.properties";
            Properties config = new Properties();
            config.load(new FileInputStream(path));
            return config.getProperty(key);
        }
        catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }

}

6、创建响应实体类

package com.liws.test.model;

@Data
public class TestInfo implements Serializable {
    private static final long serialVersionUID = 1L;

    private String organizationName;

    private String organizationType;

    private String businessType;
}

7、创建测试类

package com.liws.test.controller;

public class HttpClientTest{
    public static void main(String[] args) {
        //testHttpClientPost();
        testHttpClientGet();
    }

    //测试httpClient的post请求
    public static void testHttpClientPost(){
        ReadConfigFileInfo read = new ReadConfigFileInfo();
        String url = read.getValFromConfig("test.query");

        Map<String,String> map=new HashMap<>();
        map.put("organizationName","小明");

        HttpUtil httpUtil = new HttpUtil();
        String result = httpUtil.post(url, map);

        JSONArray array = JSON.parseArray(result);
        List<TestInfo> testInfoList = array.toJavaList(TestInfo.class);
        System.out.println(testInfoList);
    }

     //测试httpClient的Get请求
    public static void testHttpClientGet(){
        ReadConfigFileInfo read = new ReadConfigFileInfo();
        String url = read.getValFromConfig("test.test");

        List<NameValuePair> list = new LinkedList<>();
        list.add(new BasicNameValuePair("organizationName", "小明"));

        HttpUtil httpUtil = new HttpUtil();
        String result = httpUtil.get(url, list);

        JSONArray array = JSON.parseArray(result);
        List<TestInfo> testInfoList = array.toJavaList(TestInfo.class);
        System.out.println(testInfoList);
    }
}

二、被调用者

  被调用者，即服务端，其提供restful风格接口以供调用者（客户端）来调用。

  创建被调用者，可以是任意一个springboot的项目。