使用Java的URL/HttpURLConnection进行远程调用(POST请求)

利用Java的HttpURLConnection进行远程url请求(调用远程接口)
测试类：请求类型为json,以post方式请求，利用OutputStream写入数据
实体类：
public class User implements Serializable {

    private String name;
    private String password;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}
-------
@RunWith(SpringRunner.class)
@SpringBootTest
public class Springboot02ApplicationTests {

    @Autowired
    private UserService userService;

    @Test
    public void contextLoads(){
        User user = new User();
        user.setName("lisi");
        user.setPassword("123");
        //调用远程接口方法，获取返回结果类型
        String result = userService.idendifyUser(user);
        System.out.println(result);
    }
}
---------
@Service
public class UserServiceImpl implements UserService {

    public String idendifyUser(User user){
        //将对象转换为json，然后发送；
        String json = JSONObject.fromObject(user).toString();
        String result = null;
        try {
            result = UserRemoteVerify.doPost(json);
        }catch (Exception e){
            e.printStackTrace();
        }
        return result;
    }
}
---------
/**
 * 调用远程接口，验证用户数据是否合理
 */
public class UserRemoteVerify {

    //post请求
    public static String doPost(String json) throws  Exception{
        //创建URL对象,设置请求url
        URL url = new URL("http://127.0.0.1:8089/user/service");
        //调用URL对象的openConnection( )来获取HttpURLConnection对象实例
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        //请求方法为POST
        conn.setRequestMethod("POST");
        //设置连接超时为5秒
        conn.setConnectTimeout(5000);
        //允许输入输出
        conn.setDoInput(true);
        conn.setDoOutput(true);
        //不能缓存
        conn.setUseCaches(false);
        //至少要设置的两个请求头
        //设置头部信息
        conn.setRequestProperty("headerdata", "ceshiyongde");
        //一定要设置 Content-Type 要不然服务端接收不到参数
        conn.setRequestProperty("Content-Type", "application/Json; charset=UTF-8");
        //输出流包含要发送的数据,要注意数据格式编码
        OutputStream op=conn.getOutputStream();
        op.write(json.getBytes());
        //服务器返回东西了，先对响应码判断
        String result = null;
        if (conn.getResponseCode() == 200) {
            //用getInputStream()方法获得服务器返回的输入流
            InputStream in = conn.getInputStream();
            //流转换为二进制数组，read()是转换方法
            byte[] data = new byte[1024];
            in.read(data);
            result= new String(data, "UTF-8");
            in.close();
            return result;
        }
        return result;
    }

}
-------------
远程服务端代码
@Controller
public class UserController {

    /**
     * 使用json接收客户端请求，返回json数据；url="http://127.0.0.1:8089/user/service"
     */
    @PostMapping("user/service")
    @ResponseBody
    public String dealUserForJson(HttpServletRequest request)throws Exception{
        //调用处理服务，对远程数据进行校验，返回对应的结果
        String result = UserRemoteHandle.verifyUser(request);
        return result;
    }
}
--------
/**
 * 处理远程数据验证
 */
public class UserRemoteHandle {

    /**
     * 验证远程用户信息，若正确，则返回成功；否则返回失败
     */
    public static String  verifyUser(HttpServletRequest request) throws Exception{
        //根据HttpServletRequest获取输入流对象
        InputStream inputStream = null;
        try {
            inputStream = request.getInputStream();
            //使用byte[]数组存储接收到的数据
            byte[] bytes = new byte[1024];
            //从输入流中将数据读取到bytes中
            inputStream.read(bytes);
            //将bytes转换为字符串类型
            String json = new String(bytes);
            //int i = 1/0;  //服务端异常测试
            if(StringUtils.isNotBlank(json)){
                JSONObject jsonObject = JSONObject.fromObject(json);
                //将json类型转换为对象
                User user = (User)JSONObject.toBean(jsonObject,User.class);
                //判断用户名和密码是否正确;假设用户名:lisi,密码:123;
                if(user.getName().equals("lisi") && user.getPassword().equals("123")){
                    return "success";
                }
            }
        }catch (Exception e){
            e.printStackTrace();
            return "服务端出现异常";

        }finally { //释放资源
            if(inputStream != null){
                inputStream.close();
            }
        }
        //数据不符，返回错误信息
        return "message is error";
    }

}