Java代码中调用接口

代码中调用第三方接口封装一个工具类

json转换

			com.alibaba
			fastjson
			1.2.28
		

工具类

package hs.ex.dyxx.ex.util;

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
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.net.URI;
import java.util.Map;

public class RequestUtil {

    /**
     * 带参数的get请求
     * @param url
     * @param param
     * @return String
     */
    public static String doGet(String url, Map param) {
        // 创建Httpclient对象
        CloseableHttpClient httpclient = HttpClients.createDefault();

        String resultString = "";
        CloseableHttpResponse response = null;
        try {
            // 创建uri
            URIBuilder builder = new URIBuilder(url);
            if (param != null) {
                for (String key : param.keySet()) {
                    builder.addParameter(key, param.get(key));
                }
            }
            URI uri = builder.build();
            // 创建http GET请求
            HttpGet httpGet = new HttpGet(uri);
            // 执行请求
            response = httpclient.execute(httpGet);
            // 判断返回状态是否为200
            if (response.getStatusLine().getStatusCode() == 200) {
                resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return resultString;
    }

    /**
     * 不带参数的get请求
     * @param url
     * @return String
     */
    public static String doGet(String url) {
        return doGet(url, null);
    }

/**
	 * 带参数的post请求
	 * @param url
	 * @param param
	 * @return String
	 */
	public static String doPost(String url, Map param) {
		// 创建Httpclient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// 创建Http Post请求
			HttpPost httpPost = new HttpPost(url);
			// 创建参数列表
			if (param != null) {
				List paramList = new ArrayList<>();
				for (String key : param.keySet()) {
					paramList.add(new BasicNameValuePair(key, param.get(key)));
				}
				// 模拟表单
				UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
				httpPost.setEntity(entity);
			}
			// 执行http请求
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return resultString;
	}
 
	/**
	 * 不带参数的post请求
	 * @param url
	 * @return String
	 */
	public static String doPost(String url) {
		return doPost(url, null);
	}
	
	/**
	 * 传送json类型的post请求
	 * @param url
	 * @param json
	 * @return String
	 */
	public static String doPostJson(String url, String json) {
		// 创建Httpclient对象
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// 创建Http Post请求
			HttpPost httpPost = new HttpPost(url);
			// 创建请求内容
			StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
			httpPost.setEntity(entity);
			// 执行http请求
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return resultString;
	}
}

我在使用时遇到一个问题

当调用post接口时如果参数过大数据过多时调用接口失败，管道断开。当时的解决办法是把数据分开上传。网上也有一些解决办法。

使用tomcat服务器

修改Tomcat server.xml配置，取消Post请求大小限制

使用SpringBoot内嵌的Tomcat

post请求默认参数限制最大为2M，等于-1就是解除限制。

server.tomcat.max-http-post-size=-1

同时也要注意list大小也有限制

SpringMVC 接收List/数组大小默认限制为256个，可以在全局处理类@ControlerAdvice标注的全局Controller异常处理器类中添加如下代码

@InitBinder
protected void initBinder(WebDataBinder binder) {
    binder.setAutoGrowNestedPaths(true);
    binder.setAutoGrowCollectionLimit(Integer.MAX_VALUE);
}