「6-5」 httpclient+freemarker实现商城首页分类的导航数据展示

我们已经在 rest 系统中实现了商品分类的API，那么接下来我们就可以在 portal 系统中请求 rest 中的分类数据，我们可以使用 httpclient 进行不同系统之间的请求，接着将获取到的数据用 freemarker 进行展示。

创建 HttpClient

在 common 模块中依赖相关jar包

<dependencies>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
        </dependency>
        <dependency>
            <groupId>commons-net</groupId>
            <artifactId>commons-net</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </dependency>
    </dependencies>

创建 Httpclient 工具类

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
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;


/**
 * HttpClientUtil
 */
public class HttpClientUtil {

    // 连接主机超时（30s）
    public static final int HTTP_CONNECT_TIMEOUT_30S = 30 * 1000;

    // 从主机读取数据超时（3min）
    public static final int HTTP_READ_TIMEOUT_3MIN = 180 * 1000;

    /**
     * httpPost
     */
    public static String httpPost(String url, String jsonParam) throws IOException {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);

        // 设置请求头和请求参数
        if (null != jsonParam && !jsonParam.isEmpty()) {
            StringEntity entity = new StringEntity(jsonParam, "utf-8");
            entity.setContentEncoding("UTF-8");
            entity.setContentType("application/json");
            httpPost.setEntity(entity);
        }

        // 超时时间设置
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_READ_TIMEOUT_3MIN)
                .setConnectTimeout(HTTP_CONNECT_TIMEOUT_30S).build();
        httpPost.setConfig(requestConfig);

        // 发送请求
        CloseableHttpResponse response = httpclient.execute(httpPost);

        // 获取返回内容
        try {
            HttpEntity entity = response.getEntity();
            String str = EntityUtils.toString(entity);
            EntityUtils.consume(entity); // 此句关闭了流
            return str;
        } finally {
            response.close();
        }
    }

    /**
     * httpPost get Cookies
     */
    public static Map<String, Object> httpPostGetCookies(String url, String jsonParam) throws
            IOException {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);

        // 设置请求头和请求参数
        if (null != jsonParam && !jsonParam.isEmpty()) {
            StringEntity entity = new StringEntity(jsonParam, "utf-8");
            entity.setContentEncoding("UTF-8");
            entity.setContentType("application/json");
            httpPost.setEntity(entity);
        }

        // 超时时间设置
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_READ_TIMEOUT_3MIN)
                .setConnectTimeout(HTTP_CONNECT_TIMEOUT_30S).build();
        httpPost.setConfig(requestConfig);

        // 发送请求
        CloseableHttpResponse response = httpclient.execute(httpPost);

        // 获取返回内容
        try {
            HttpEntity entity = response.getEntity();
            String str = EntityUtils.toString(entity);
            EntityUtils.consume(entity); // 此句关闭了流

            // 获取数据内容
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("result", str);

            // 获取返回到额Cookies
            Header[] headers = response.getHeaders("Set-Cookie");
            map.put("cookies", headers);

            return map;
        } finally {
            response.close();
        }
    }

    /**
     * httpGet
     */
    public static String httpGet(String url) throws  IOException {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(url);

        // 超时时间设置
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_READ_TIMEOUT_3MIN)
                .setConnectTimeout(HTTP_CONNECT_TIMEOUT_30S).build();
        httpGet.setConfig(requestConfig);

        // 发送请求
        CloseableHttpResponse response = httpclient.execute(httpGet);

        // 获取返回内容
        try {
            HttpEntity entity = response.getEntity();
            String strResult = EntityUtils.toString(entity);
            return strResult;
        } finally {
            response.close();
        }
    }

    /**
     * httpGet with Cookies
     */
    public static String httpGetWithCookies(String url, Header[] headers) throws  IOException {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(url);

        // 超时时间设置
        RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_READ_TIMEOUT_3MIN)
                .setConnectTimeout(HTTP_CONNECT_TIMEOUT_30S).build();
        httpGet.setConfig(requestConfig);

        // 设置请求头
        if (headers != null && headers.length > 0) {
            httpGet.setHeaders(headers);
        }

        // 发送请求
        CloseableHttpResponse response = httpclient.execute(httpGet);

        // 获取返回内容
        try {
            HttpEntity entity = response.getEntity();
            String strResult = EntityUtils.toString(entity);
            return strResult;
        } finally {
            response.close();
        }
    }

}

添加 source 配置文件

# REST
REST_URL = http://127.0.0.1:8088/rest/

添加配置路径文件

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">
      <property name="location">
          <value>classpath:resource/resource.properties</value>
      </property>
  </bean>

Service 的具体实现

@Service
public class CategoriesServiceImpl implements CategoriesService {

    @Value("${REST_URL}")
    private String REST_URL;
    @Value("${CATEGORY_LIST}")
    private String CATEGORY_LIST;

    @Override
    public Res_Categories getCategories() {
        try {
            String jsonResutlt = HttpClientUtil.httpGet(REST_URL + CATEGORY_LIST);
            Res_Categories res_categories = GsonUtil.fromJson(Res_Categories.class, jsonResutlt);
            return res_categories;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

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