在项目开发中经常会遇到调用第三方接口的情况,比如说调用第三方的天气预报接口。

使用流程
【1】准备工作:在项目的工具包下导入HttpClientUtil这个工具类,或者也可以使用Spring框架的restTemplate来调用,上面有调用接口的方法【分为Get和Post方式的有参和无参调用】:

package com.njsc.credit.util;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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.client.utils.URIBuilder;
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.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpClientUtil {

    /**
     * 带参数的get请求
     * @param url
     * @param param
     * @return String
     */
    public static String doGet(String url, Map<String, String> 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<String, String> 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<NameValuePair> 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;
    }
}

【2】创建url和访问key 以及参数等:

代码如下:

/**
 * 聚合接口校验身份证
 * @param idCard
 * @param realName
 * @return boolean
 */
 public boolean identityCheck(String idCard, String realName){
    logger.info("-----------------调用聚合数据 身份证验证API BEGIN--------------->");
    String key = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    String url = "http://op.juhe.cn/idcard/query" + "?key=" + key + "&idcard=" + idCard + "&realname=" + realName;
    logger.info("请求url:" + url);
    boolean match = false; //是否匹配
    try {
        String result = HttpClientUtil.doGet(url);
        System.out.println("请求结果:" + result);
        IdentityCheckResult identityCheckResult = JsonUtils.parse(result, IdentityCheckResult.class);
        IdentityCheck identityCheck = JsonUtils.parse(result, "result", IdentityCheck.class);
        logger.info(identityCheckResult);
        logger.info(identityCheck.toString());
        if(identityCheckResult.correct() && identityCheck.getRes() == 1){
            match = true;
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    logger.info("<-----------------调用聚合数据 身份证验证API END---------------");
    return match;
 }

【3】请求这个第三方接口:

使用HttpClientUtil工具类中的doGet方法来请求URL,得到结果,现在大多数是一个json字符串,类型为String

【4】根据接口返回数据格式来解析数据:

可以看到,返回参数有六个,所以在项目中新建一个bean,包含以上六个字段,用来接住返回数据,如下:

因为接口返回的数据是一个json的字符串,类型实际上是一个String字符串,要解析数据,用工具类JsonUtils的parse方法将字符串转换为Java对象,JsonUtils的代码如下:

package com.eqianxian.commons.utils.json;

import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.PropertyFilter;
import com.alibaba.fastjson.serializer.SerializerFeature;

/**
 * 在系统中统一使用这个,以方便将来切换不同的JSON生成工具
 * 
 * @author KelvinZ
 * 
 */
    public class JsonUtils {
    public static final int TYPE_FASTJSON = 0;
    public static final int TYPE_GSON = 1;

    /**
     * <pre>
     * 对象转化为json字符串
     * 
     * @param obj 待转化对象
     * @return 代表该对象的Json字符串
     */
     public static final String toJson(final Object obj) {
        return JSON.toJSONString(obj);
        // return gson.toJson(obj);
     }

    /**
     * <pre>
     * 对象转化为json字符串
     * 
     * @param obj 待转化对象
     * @return 代表该对象的Json字符串
     */
     public static final String toJson(final Object obj, SerializerFeature... features) {
        return JSON.toJSONString(obj, features);
        // return gson.toJson(obj);
     }

    /**
     * 对象转化为json字符串并格式化
     * 
     * @param obj
     * @param format 是否要格式化
     * @return
     */
     public static final String toJson(final Object obj, final boolean format) {
        return JSON.toJSONString(obj, format);
     }

    /**
     * 对象对指定字段进行过滤处理,生成json字符串
     * 
     * @param obj
     * @param fields 过滤处理字段
     * @param ignore true做忽略处理,false做包含处理
     * @param features json特征,为null忽略
     * @return
     */
     public static final String toJson(final Object obj, final String[] fields, final boolean ignore,
            SerializerFeature... features) {
        if (fields == null || fields.length < 1) {
            return toJson(obj);
        }
        if (features == null)
            features = new SerializerFeature[] { SerializerFeature.QuoteFieldNames };
        return JSON.toJSONString(obj, new PropertyFilter() {
            @Override
            public boolean apply(Object object, String name, Object value) {
                for (int i = 0; i < fields.length; i++) {
                    if (name.equals(fields[i])) {
                        return !ignore;
                    }
                }
                return ignore;
            }
        }, features);
     }

    /**
     * <pre>
     * 解析json字符串中某路径的值
     * 
     * @param json
     * @param path
     * @return
     */
     @SuppressWarnings("unchecked")
     public static final <E> E parse(final String json, final String path) {
        String[] keys = path.split(",");
        JSONObject obj = JSON.parseObject(json);
        for (int i = 0; i < keys.length - 1; i++) {
            obj = obj.getJSONObject(keys[i]);
        }
        return (E) obj.get(keys[keys.length - 1]);
     }

    /**
     * <pre>
     * json字符串解析为对象
     * 
     * @param json 代表一个对象的Json字符串
     * @param clazz 指定目标对象的类型,即返回对象的类型
     * @return 从json字符串解析出来的对象
     */
     public static final <T> T parse(final String json, final Class<T> clazz) {
        return JSON.parseObject(json, clazz);
     }

    /**
     * <pre>
     * json字符串解析为对象
     * 
     * @param json json字符串
     * @param path 逗号分隔的json层次结构
     * @param clazz 目标类
     */
     public static final <T> T parse(final String json, final String path, final Class<T> clazz) {
        String[] keys = path.split(",");
        JSONObject obj = JSON.parseObject(json);
        for (int i = 0; i < keys.length - 1; i++) {
            obj = obj.getJSONObject(keys[i]);
        }
        String inner = obj.getString(keys[keys.length - 1]);
        return parse(inner, clazz);
     }

    /**
     * 将制定的对象经过字段过滤处理后,解析成为json集合
     * 
     * @param obj
     * @param fields
     * @param ignore
     * @param clazz
     * @param features
     * @return
     */
     public static final <T> List<T> parseArray(final Object obj, final String[] fields, boolean ignore,
            final Class<T> clazz, final SerializerFeature... features) {
        String json = toJson(obj, fields, ignore, features);
        return parseArray(json, clazz);
     }

    /**
     * <pre>
     * 从json字符串中解析出一个对象的集合,被解析字符串要求是合法的集合类型
     * (形如:["k1":"v1","k2":"v2",..."kn":"vn"])
     * 
     * @param json - [key-value-pair...]
     * @param clazz
     * @return
     */
     public static final <T> List<T> parseArray(final String json, final Class<T> clazz) {
        return JSON.parseArray(json, clazz);
     }

    /**
     * <pre>
     * 从json字符串中按照路径寻找,并解析出一个对象的集合,例如:
     * 类Person有一个属性name,要从以下json中解析出其集合:
     * {
     *  "page_info":{
     *      "items":{
     *          "item":[{"name":"KelvinZ"},{"name":"Jobs"},...{"name":"Gates"}]
     *  }
     * }
     * 使用方法:parseArray(json, "page_info,items,item", Person.class),
     * 将根据指定路径,正确的解析出所需集合,排除外层干扰
     * 
     * @param json json字符串
     * @param path 逗号分隔的json层次结构
     * @param clazz 目标类
     * @return
     */
     public static final <T> List<T> parseArray(final String json, final String path, final Class<T> clazz) {
        String[] keys = path.split(",");
        JSONObject obj = JSON.parseObject(json);
        for (int i = 0; i < keys.length - 1; i++) {
            obj = obj.getJSONObject(keys[i]);
        }
        String inner = obj.getString(keys[keys.length - 1]);
        List<T> ret = parseArray(inner, clazz);
        return ret;
     }

    /**
     * <pre>
     * 有些json的常见格式错误这里可以处理,以便给后续的方法处理
     * 常见错误:使用了\" 或者 "{ 或者 }",腾讯的页面中常见这种格式
     * 
     * @param invalidJson 包含非法格式的json字符串
     * @return
     */
     public static final String correctJson(final String invalidJson) {
        String content = invalidJson.replace("\\\"", "\"").replace("\"{", "{").replace("}\"", "}");
        return content;
     }

    /**
     * 格式化Json
     * 
     * @param json
     * @return
     */
     public static final String formatJson(String json) {
        Map<?, ?> map = (Map<?, ?>) JSON.parse(json);
        return JSON.toJSONString(map, true);
     }

    /**
     * 获取json串中的子json
     * 
     * @param json
     * @param path
     * @return
     */
     public static final String getSubJson(String json, String path) {
        String[] keys = path.split(",");
        JSONObject obj = JSON.parseObject(json);
        for (int i = 0; i < keys.length - 1; i++) {
            obj = obj.getJSONObject(keys[i]);
            System.out.println(obj.toJSONString());
        }
        return obj != null ? obj.getString(keys[keys.length - 1]) : null;
     }
}

来源:https://blog.csdn.net/qq_35860138/article/details/82967727

作者:inner_peace8