java实现利用httpclient访问接口

利用枚举先new 四种访问方式

package util;

import org.apache.http.client.methods.*;

/**
 * @author jreffchen
 */
public enum HttpRequestMethedEnum {
    // HttpGet请求
    HttpGet {
        @Override
        public HttpRequestBase createRequest(String url) { return new HttpGet(url); }
    },
    // HttpPost 请求
    HttpPost {
        @Override
        public HttpRequestBase createRequest(String url) { return new HttpPost(url); }
    },
    // HttpPut 请求
    HttpPut {
        @Override
        public HttpRequestBase createRequest(String url) { return new HttpPut(url); }
    },
    // HttpDelete 请求
    HttpDelete {
        @Override
        public HttpRequestBase createRequest(String url) { return new HttpDelete(url); }
    };

    public HttpRequestBase createRequest(String url) { return null; }
}

写一个HttpClientUtil通用类

package util;

import com.alibaba.fastjson.JSON;
import org.apache.http.HttpEntity;
import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.*;
import org.apache.http.entity.ContentType;
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 java.io.IOException;
import java.util.Map;

/**
 * @author jreffchen
 */
public class HttpClientUtil {

    /**
     * httpclient使用步骤
     * 1、创建一个HttpClient对象;
     * 2、创建一个Http请求对象并设置请求的URL，比如GET请求就创建一个HttpGet对象，POST请求就创建一个HttpPost对象;
     * 3、如果需要可以设置请求对象的请求头参数，也可以往请求对象中添加请求参数;
     * 4、调用HttpClient对象的execute方法执行请求;
     * 5、获取请求响应对象和响应Entity;
     * 6、从响应对象中获取响应状态，从响应Entity中获取响应内容;
     * 7、关闭响应对象;
     * 8、关闭HttpClient.
     */

    private static RequestConfig requestConfig = RequestConfig.custom()
            //从连接池中获取连接的超时时间
            // 要用连接时尝试从连接池中获取，若是在等待了一定的时间后还没有获取到可用连接（比如连接池中没有空闲连接了）则会抛出获取连接超时异常。
            .setConnectionRequestTimeout(15000)
            //与服务器连接超时时间：httpclient会创建一个异步线程用以创建socket连接，此处设置该socket的连接超时时间
            //连接目标url的连接超时时间，即客服端发送请求到与目标url建立起连接的最大时间。超时时间3000ms过后，系统报出异常
            .setConnectTimeout(15000)
            //socket读数据超时时间：从服务器获取响应数据的超时时间
            //连接上一个url后，获取response的返回等待时间 ，即在与目标url建立连接后，等待放回response的最大时间，在规定时间内没有返回响应的话就抛出SocketTimeout。
            .setSocketTimeout(15000)
            .build();


    /**
     * 发送http请求
     *
     * @param requestMethod 请求方式（HttpGet、HttpPost、HttpPut、HttpDelete）
     * @param url 请求路径
     * @param params post请求参数
     * @param header 请求头
     * @return 响应文本
     */
    public static String sendHttp(HttpRequestMethedEnum requestMethod, String url, Map params, Map header) {
        //1、创建一个HttpClient对象;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse httpResponse = null;
        String responseContent = null;
        //2、创建一个Http请求对象并设置请求的URL，比如GET请求就创建一个HttpGet对象，POST请求就创建一个HttpPost对象;
        HttpRequestBase request = requestMethod.createRequest(url);
        request.setConfig(requestConfig);
        //3、如果需要可以设置请求对象的请求头参数，也可以往请求对象中添加请求参数;
        if (header != null) {
            for (Map.Entry entry : header.entrySet()) {
                request.setHeader(entry.getKey(), entry.getValue());
            }
        }
        // 往对象中添加相关参数
        try {
            if (params != null) {
                ((HttpEntityEnclosingRequest) request).setEntity(
                        new StringEntity(JSON.toJSONString(params),
                                ContentType.create("application/json", "UTF-8")));
            }
            //4、调用HttpClient对象的execute方法执行请求;
            httpResponse = httpClient.execute(request);
            //5、获取请求响应对象和响应Entity;
            HttpEntity httpEntity = httpResponse.getEntity();
            //6、从响应对象中获取响应状态，从响应Entity中获取响应内容;
            if (httpEntity != null) {
                responseContent = EntityUtils.toString(httpEntity, "UTF-8");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                //7、关闭响应对象;
                if (httpResponse != null) {
                    httpResponse.close();
                }
                //8、关闭HttpClient.
                if (httpClient != null) {
                    httpClient.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return responseContent;
    }
}

最后，单元测试

Get请求：

/**
 * 获取流程定义列表
 * @throws UnsupportedEncodingException 转码异常
 */
@Test
public void getProcessDefinitionList() throws UnsupportedEncodingException {
    String url = "http://127.0.0.1:8080/activiti-rest/service/repository/process-definitions";

    // 存储相关的header值
    Map header = new HashMap();
    //username:password--->访问的用户名，密码,并使用base64进行加密，将加密的字节信息转化为string类型，encoding--->token
    String encoding = DatatypeConverter.printBase64Binary("kermit:kermit".getBytes("UTF-8"));
    header.put("Authorization", "Basic " + encoding);

    String response = HttpClientUtil.sendHttp(HttpRequestMethedEnum.HttpGet,url, null,header);
    System.out.println(JSON.toJSONString(JSONObject.parseObject(response),true));
}

Post请求：

/**
 * 历史流程实例列表(以post方式，推荐)
 * @throws UnsupportedEncodingException 转码异常
 */
@Test
public void postHistoryProcessInstancesList() throws UnsupportedEncodingException {
    String url = "http://127.0.0.1:8080/activiti-rest/service/query/historic-process-instances";

    // 存储相关的header值
    Map header = new HashMap();
    //username:password--->访问的用户名，密码,并使用base64进行加密，将加密的字节信息转化为string类型，encoding--->token
    String encoding = DatatypeConverter.printBase64Binary("kermit:kermit".getBytes("UTF-8"));
    header.put("Authorization", "Basic " + encoding);

    // 相关请求参数
    Map params = new HashMap();
    params.put("processDefinitionKey", "process");

    String response = HttpClientUtil.sendHttp(HttpRequestMethedEnum.HttpPost,url,params, header);
    System.out.println(JSON.toJSONString(JSONObject.parseObject(response),true));
}

Put请求

/**
 * 更新任务
 *
 * @throws UnsupportedEncodingException 转码异常
 */
@Test
public void putProcessRuntimeTask() throws UnsupportedEncodingException {
    String url = "http://127.0.0.1:8080/activiti-rest/service/runtime/tasks/50019";

    // 存储相关的header值
    Map header = new HashMap();
    //username:password--->访问的用户名，密码,并使用base64进行加密，将加密的字节信息转化为string类型，encoding--->token
    String encoding = DatatypeConverter.printBase64Binary("kermit:kermit".getBytes("UTF-8"));
    header.put("Authorization", "Basic " + encoding);

    // 存储相关的params值
    Map params = new HashMap();
    params.put("assignee", "zhangsan");

    String response = HttpClientUtil.sendHttp(HttpRequestMethedEnum.HttpPut, url, params, header);
    System.out.println(JSON.toJSONString(JSONObject.parseObject(response), true));
}

Delete请求

/**
 * 删除任务的一个IdentityLink
 *
 * @throws UnsupportedEncodingException 转码异常
 */
@Test
public void deleteProcessRuntimeIdentityLink() throws UnsupportedEncodingException {
    String url = "http://127.0.0.1:8080/activiti-rest/service/runtime/tasks/50014/identitylinks/users/wangwu/candidate";

    // 存储相关的header值
    Map header = new HashMap();
    //username:password--->访问的用户名，密码,并使用base64进行加密，将加密的字节信息转化为string类型，encoding--->token
    String encoding = DatatypeConverter.printBase64Binary("kermit:kermit".getBytes("UTF-8"));
    header.put("Authorization", "Basic " + encoding);

    String response = HttpClientUtil.sendHttp(HttpRequestMethedEnum.HttpDelete, url, null, header);
    System.out.println(JSON.toJSONString(JSONObject.parseObject(response), true));
}