Java调用第三方接口的方法

(1)实体类

public class User {
    private String uid;
    private String uname;
    private String upassword;
    private String usex; }
//自己实现Get/Set方法,toString方法

(2)第三方api接口


@RestController
@RequestMapping("users")
public class UserController {
    @GetMapping("/get")
    public String hello() {
        System.out.println("访问GET成功啦...");
        return "GET执行啦!!!";
   }    
   @PostMapping("/post")
    public String reg(@RequestBody User user) {
        System.out.println("访问POST成功啦:"+user);
        return "POST执行啦:"+user;
    } }

(3)application.xml

server:
  port: 8089

注意:以下方法均使用上面的api接口

1.方式一:通过JDK网络类Java.net.HttpURLConnection

(1)HttpClientUtil工具类


public class HttpClientUtil {
      //以post方式调用对方接口方法
    public static String doPost(String pathUrl, String data){
        OutputStreamWriter out = null;
        BufferedReader br = null;
        String result = "";
        try {
            URL url = new URL(pathUrl);//import java.net.URL;
            //打开和url之间的连接(java.net.HttpURLConnection;)
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            //设定请求的方法为"POST",默认是GET
            //post与get的不同之处在于post的参数不是放在URL字串里面,而是放在http请求的正文内。
            conn.setRequestMethod("POST");

            //设置30秒连接超时
            conn.setConnectTimeout(30000);
            //设置30秒读取超时
            conn.setReadTimeout(30000);

            // 设置是否向httpUrlConnection输出,因为这个是post请求,参数要放在http正文内,因此需要设为true, 默认情况下是false;
            conn.setDoOutput(true);
            // 设置是否从httpUrlConnection读入,默认情况下是true;
            conn.setDoInput(true);

            // Post请求不能使用缓存
            conn.setUseCaches(false);

            //设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");  //维持长链接
            conn.setRequestProperty("Content-Type", "application/json;charset=utf-8");

            //连接,从上述url.openConnection()至此的配置必须要在connect之前完成,
            conn.connect();

            /**
             * 下面的三句代码,就是调用第三方http接口
             */
            //获取URLConnection对象对应的输出流
            //此处getOutputStream会隐含的进行connect(即:如同调用上面的connect()方法,所以在开发中不调用上述的connect()也可以)。
            out = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
            //发送请求参数即数据
            out.write(data);
            //flush输出流的缓冲
            out.flush();

            /**
             * 下面的代码相当于,获取调用第三方http接口后返回的结果
             */
            //获取URLConnection对象对应的输入流
            InputStream is = conn.getInputStream();
            //构造一个字符流缓存
            br = new BufferedReader(new InputStreamReader(is));
            String str = "";
            while ((str = br.readLine()) != null){
                result += str;
            }
            System.out.println(result);
            //关闭流
            is.close();
            //断开连接,disconnect是在底层tcp socket链接空闲时才切断,如果正在被其他线程使用就不切断。
            conn.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if (out != null){
                    out.close();
                }
                if (br != null){
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 以get方式调用对方接口方法
     * @param pathUrl
     */
    public static String doGet(String pathUrl){
        BufferedReader br = null;
        String result = "";
        try {
            URL url = new URL(pathUrl);

            //打开和url之间的连接
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            //设定请求的方法为"GET",默认是GET
            //post与get的不同之处在于post的参数不是放在URL字串里面,而是放在http请求的正文内。
            conn.setRequestMethod("GET");

            //设置30秒连接超时
            conn.setConnectTimeout(30000);
            //设置30秒读取超时
            conn.setReadTimeout(30000);

            // 设置是否向httpUrlConnection输出,因为这个是post请求,参数要放在http正文内,因此需要设为true, 默认情况下是false;
            conn.setDoOutput(true);
            // 设置是否从httpUrlConnection读入,默认情况下是true;
            conn.setDoInput(true);

            // Post请求不能使用缓存(get可以不使用)
            conn.setUseCaches(false);

            //设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");  //维持长链接
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");

            //连接,从上述url.openConnection()至此的配置必须要在connect之前完成,
            conn.connect();

            /**
             * 下面的代码相当于,获取调用第三方http接口后返回的结果
             */
            //获取URLConnection对象对应的输入流
            InputStream is = conn.getInputStream();
            //构造一个字符流缓存
            br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            String str = "";
            while ((str = br.readLine()) != null){
                result += str;
            }
            System.out.println(result);
            //关闭流
            is.close();
            //断开连接,disconnect是在底层tcp socket链接空闲时才切断,如果正在被其他线程使用就不切断。
            conn.disconnect();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if (br != null){
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    } }

(2)测试

public class HttpClientUtilTest {
    @Test
    public void testHttpClientUtil2Test() {
 		//测试get方法
        String s = HttpClientUtil.doGet("http://localhost:8089/users/get");
        System.out.println("get方法:"+s);
        //测试post方法
        User user = new User();
        user.setUid("1");
        user.setUname("zs");
        user.setUpassword("123");
        user.setUsex("男");
//        把对象转换为json格式
//        String s1 = JsonUtil.toJson(user);
//        String s = user.toString();
//        把对象转换为json格式
        String s1 = JSON.toJSONString(user);
        String postString = HttpClientUtil2.doPost("http://localhost:8089/users/post", s1);
        System.out.println("post方法:" + postString);
    } }

2.方式二:通过Apache common封装好的HttpClient

(1)引入依赖

 
        
        <dependency>
            <groupId>commons-httpclientgroupId>
            <artifactId>commons-httpclientartifactId>
            <version>3.1version>
        dependency>
        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>fastjsonartifactId>
            <version>1.2.28version>
        dependency>

(2)HttpClientUtil

//通过Apache common封装好的HttpClient
public class HttpClientUtil2 {

    public static String doGet(String url, String charset) {
        /**
         * 1.生成HttpClient对象并设置参数
         */
        HttpClient httpClient = new HttpClient();
        //设置Http连接超时为5秒
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(5000);

        /**
         * 2.生成GetMethod对象并设置参数
         */
        GetMethod getMethod = new GetMethod(url);
        //设置get请求超时为5秒
        getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 5000);
        //设置请求重试处理,用的是默认的重试处理:请求三次
        getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());

        String response = "";

        /**
         * 3.执行HTTP GET 请求
         */
        try {
            int statusCode = httpClient.executeMethod(getMethod);

            /**
             * 4.判断访问的状态码
             */
            if (statusCode != HttpStatus.SC_OK) {
                System.err.println("请求出错:" + getMethod.getStatusLine());
            }

            /**
             * 5.处理HTTP响应内容
             */
            //HTTP响应头部信息,这里简单打印
            Header[] headers = getMethod.getResponseHeaders();
            for (Header h : headers) {
                System.out.println(h.getName() + "---------------" + h.getValue());
            }
            //读取HTTP响应内容,这里简单打印网页内容
            //读取为字节数组
            byte[] responseBody = getMethod.getResponseBody();
            response = new String(responseBody, charset);
            System.out.println("-----------response:" + response);
            //读取为InputStream,在网页内容数据量大时候推荐使用
            //InputStream response = getMethod.getResponseBodyAsStream();

        } catch (HttpException e) {
            //发生致命的异常,可能是协议不对或者返回的内容有问题
            System.out.println("请检查输入的URL!");
            e.printStackTrace();
        } catch (IOException e) {
            //发生网络异常
            System.out.println("发生网络异常!");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            /**
             * 6.释放连接
             */
            getMethod.releaseConnection();
        }
        return response;
    }

    /**
     * post请求
     *
     * @param url
     * @param json
     * @return
     */
    public static String doPost(String url, JSONObject json) {
        HttpClient httpClient = new HttpClient();
        PostMethod postMethod = new PostMethod(url);

        postMethod.addRequestHeader("accept", "*/*");
        postMethod.addRequestHeader("connection", "Keep-Alive");
        //设置json格式传送
        postMethod.addRequestHeader("Content-Type", "application/json;charset=utf-8");
        //必须设置下面这个Header
        postMethod.addRequestHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.81 Safari/537.36");
        //添加请求参数
        //postMethod.addParameter("param", json.getString("param"));
        StringRequestEntity param = new StringRequestEntity(json.getString("param"));
        postMethod.setRequestEntity(param);
        String res = "";
        try {
            int code = httpClient.executeMethod(postMethod);
            if (code == 200) {
                byte[] responseBody = postMethod.getResponseBody();
                res = new String(responseBody, "UTF-8");
                //res = postMethod.getResponseBodyAsString();
                System.out.println(res);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return res;
    }
}

(3)测试

public class HttpClientUtil2Test {
    @Test
    public void testApi() {
        //测试get方法
        String s = HttpClientUtil2.doGet("http://localhost:8089/users/get", "UTF-8");
        System.out.println("get方法:"+s);
        //测试post方法
        User user = new User();
        user.setUid("2");
        user.setUname("lisi");
        user.setUpassword("321");
        user.setUsex("女");
        JSONObject jsonObject = new JSONObject();
        String s1 = JSON.toJSONString(user);
        jsonObject.put("param",s1);
        String postString = HttpClientUtil2.doPost("http://localhost:8089/users/post",jsonObject);
        System.out.println("post方法:"+postString);
    } }

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