Java使用OkHttps工具类调用外部接口

前言

现在公司业务已止不是传统的增删改查等简单的业务处理操作，而是对数据各种联调三方接口与其他系统进行交互等，那么就需要我们在后台java中进行外部接口的调用，本文采用OkHttps工具类对接微信接口为大家简单介绍下，java调用外部接口进行数据交互。

第一步新建接口Demo

本文采用Idea作为开发工具

依次按照 file---new---project

紧接着如下

如果这样写就会提示

因为Idea中创建项目-项目名称必须小写

接着继续勾选Jar依赖

Jar依赖选择完成之后，确认项目名称跟所在目录

更具体的步骤请查看公众号之前写的

学习栈新年献礼-SpringBoot第一弹

项目创建好之后，创建两个package，用来存放我们的工具类，与接口

先引入项目所需jar包依赖

buildscript {
    ext {
        springBootVersion = '2.1.2.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'java'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
apply plugin: 'war'
group = 'com.ahdd99.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'
repositories {
    mavenCentral()
}

dependencies {
    compile 'org.springframework.boot:spring-boot-starter-data-jpa'
    compile 'org.springframework.boot:spring-boot-starter-jdbc'
    compile 'org.springframework.boot:spring-boot-starter-web'
    compile 'mysql:mysql-connector-java'
    compile 'org.springframework.boot:spring-boot-starter-test'
    compile 'com.squareup.okhttp3:okhttp:3.5.0'
    compile group: 'com.google.code.gson', name: 'gson', version: '2.7'
    compile 'com.xiaoleilu:hutool-all:3.1.0'
    compile 'com.squareup.okhttp3:okhttp:3.5.0'
    compileOnly 'org.projectlombok:lombok:1.16.6'
    testCompile 'org.springframework.boot:spring-boot-starter-test'
    providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'
    providedRuntime 'org.apache.tomcat:tomcat-jasper:8.5.28'
}

紧接着，在util包里面引入我们的okhttps工具类

OkHttps工具类中主要封装了get与post请求，这里简单让大家看下，源代码会贴在文章末尾

/**
 * OkHttpUtils 工具类
 */
@Slf4j
public class OkHttpUtils {

  private final static OkHttpClient client = new OkHttpClient().newBuilder()
      .writeTimeout(60, TimeUnit.SECONDS)
      .readTimeout(60, TimeUnit.SECONDS)
      .build();
  public static JsonObject doGetRetJson(String url) throws IOException {
    return doGetRetJsonElement(url).getAsJsonObject();
  }

  public static JsonElement doGetRetJsonElement(String url) throws IOException {
    Request request = new Request.Builder().url(url).build();
    return sendSyncRequestRetJsonElement(request);
  }

  public static JsonObject doPostRetJson(String url, String jsonBody) throws IOException {
    return doPostRetJsonElement(url, jsonBody).getAsJsonObject();
  }

  public static JsonElement doPostRetJsonElement(String url, String jsonBody) throws IOException {
    RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), jsonBody);
    Request request = new Request.Builder().url(url).post(requestBody).build();
    return sendSyncRequestRetJsonElement(request);
  }
  public static String doPostRetJsonString(String url, String jsonBody) throws IOException {
    RequestBody requestBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"), jsonBody);
    Request request = new Request.Builder().url(url).post(requestBody).build();
    return sendSyncRequestRetString(request);
  }
  public static String doPostRetString(String url, String textBody) throws IOException {
    RequestBody requestBody = RequestBody.create(MediaType.parse("application/x-www-form-urlencoded; charset=utf-8"), textBody);
    Request request = new Request.Builder().url(url).post(requestBody).build();
    return sendSyncRequestRetString(request);
  }

  public static void doPost(String url, Map<String, String> params) throws IOException {
    FormBody.Builder formBuilder = new FormBody.Builder();
    for (String key : params.keySet()) {
      formBuilder.add(key, params.get(key));
    }
    Request request = new Request.Builder().url(url).post(formBuilder.build()).build();
    sendSyncRequestRetString(request);
  }

  public static JsonObject doPostRetJson(String url, Map<String, String> params) throws IOException {
    FormBody.Builder formBuilder = new FormBody.Builder();
    for (String key : params.keySet()) {
      formBuilder.add(key, params.get(key));
    }
    Request request = new Request.Builder().url(url).post(formBuilder.build()).build();
    return sendSyncRequestRetJson(request);
  }

  /**
   * 支付宝请求返回form
   *
   * @param url
   * @param params
   * @return
   * @throws IOException   */
  public static String doPostResString(String url, Map<String, String> params) throws IOException {
    FormBody.Builder formBuilder = new FormBody.Builder();
    for (String key : params.keySet()) {
      formBuilder.add(key, params.get(key));
    }
    Request request = new Request.Builder().url(url).post(formBuilder.build()).build();
    return sendSyncRequestRetString(request);
  }

  public static JsonObject doPostRetJsonForUploadFile(String url, Map<String, Object> params) throws IOException {
    MultipartBody.Builder formBuilder = new MultipartBody.Builder();
    formBuilder.setType(MultipartBody.FORM);
    params.forEach((key, value) -> {
      if (value instanceof File) {
        File file = (File) value;
        formBuilder.addFormDataPart(key, file.getName(), RequestBody.create(MediaType.parse("application/pdf; charset=utf-8"), file));
      } else {
        formBuilder.addFormDataPart(key, value.toString());
      }
    });
    Request request = new Request.Builder().url(url).post(formBuilder.build()).build();
    return sendSyncRequestRetJson(request);
  }

  private static JsonObject sendSyncRequestRetJson(Request request) throws IOException {
    return sendSyncRequestRetJsonElement(request).getAsJsonObject();
  }

  private static JsonElement sendSyncRequestRetJsonElement(Request request) throws IOException {
    return JsonUtils.toJsonElement(sendSyncRequestRetString(request));
  }

  private static String sendSyncRequestRetString(Request request) throws IOException {
    Response response = client.newCall(request).execute();
    if (!response.isSuccessful()) {

      throw new IOException("请求出错，出错信息：" + response.message());
    }
    String retString = response.body().string();
    if (StrUtil.isEmpty(retString)) {
      return "";
    }
    return retString;
  }
}

kHttps工具类引入完成之后，引入JsonUtils工具类，这个主要是帮助我们吧参数封给JSON，免去我们在每个接口中再进行单独封装

/**
 * 参数转json工具类
 */
public class JsonUtils {

  private static final JsonParser JSON_PARSER = new JsonParser();
  public static String toJson(Object object) {
    Gson gson = new GsonBuilder().create();
    return gson.toJson(object);
  }

  public static JsonObject toJsonObject(String json) {
    return JSON_PARSER.parse(json).getAsJsonObject();
  }

  public static JsonArray jsonObjectToJsonArray(JsonObject jsonObject) {
    JsonArray jsonArray = new JsonArray();
    jsonArray.add(jsonObject);
    return jsonArray;
  }

  public static JsonElement toJsonElement(String json) {
    return JSON_PARSER.parse(json);
  }
}

工具类都引入完毕之后，就是我们的重头戏了

接口开发第一步，抽离接口Api工具类

将所有的接口路径抽离为工具类，并且定义为常量，方便后期维护

/**
 * 接口api路径
 * @author gyk
 * @date 2019-03-27 11:27
 */
public class WxPortApi {

    /**
     * 接口请求路径
     */
    public final static  String WX_API = "https://api.weixin.qq.com";
    /**
     * 学习栈appID
     */
    public final  static  String WX_APP_ID = "";
    /**
     * 学习栈AppSecret
     */
    public final  static  String AppSecret = "";
    /**
     * 获取access_token接口
     */
    public final static  String ACCESS_TOKEN = "/cgi-bin/token";
}

下来就是接口调用

创建package service

编写接口service层业务处理

/**
 * 获取公众号的access_token
 * @param appId --- 微信appId
 * @param secret  --- 微信秘钥
 * @return
 */
public JsonObject getAccessTocken(String appId, String secret){
    JsonObject resultJson = new JsonObject();
    Map<String, String> params = new HashMap<>(3);
    //赋值接口需传递参数
    //获取access_token填写client_credential
    params.put("grant_type", "client_credential");
    // 第三方用户唯一凭证
    params.put("appid", appId);
    // 第三方用户唯一凭证密钥，即appSecret
    params.put("secret", secret);
    try {
        //调用okHttps工具类进行接口调用
        return OkHttpUtils.doPostRetJson(WxPortApi.WX_API + WxPortApi.ACCESS_TOKEN, params);
    } catch (IOException e) {
        //赋值失败结果
        resultJson.addProperty("result","-1");
        resultJson.addProperty("msg",msg +"获取access_token失败");
        return resultJson;
    }

}

然后编写单元测试

/**
 * 测试获取公众号的access_token
 */
@Test
public void getAccessTocken() {
    WxPortService wxPortService = new WxPortService();
    JsonObject jsonObject =  wxPortService.getAccessTocken(WxPortApi.WX_APP_ID, WxPortApi.AppSecret);
    //获取错误码
    String error_code = String.valueOf(jsonObject.get("errcode"));
    //如果errcode 为空，那么证明获取的正确，不然获取失败
    if("null".equals(error_code)){
        //打印得到的access_token
        System.out.println(String.valueOf(jsonObject.get("access_token")));
    }

}

在这里有一个小坑大家要注意，java中String.valueOf() 如果你传入的是NULL 那么java会给你返回"Null" 字符串

剩下的微信接口对接将于后面进一步详细讲解

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