1、开通接口

天气预报接口服务使用的聚合数据提供的免费接口，每天可以100次免费调用。可以通过https://www.juhe.cn/docs/api/id/73注册及开通。

2、通过Java发起城市天气查询

package cn.juhe;

import net.sf.json.JSONObject;

import java.io.*;

import java.net.HttpURLConnection;

import java.net.URL;

import java.net.URLEncoder;

import java.nio.charset.StandardCharsets;

import java.util.HashMap;

import java.util.Map;

public class SimpleWeather {

// 天气情况查询接口地址

public static String API_URL = "http://apis.juhe.cn/simpleWeather/query";

// 接口请求Key

public static String API_KEY = "xxxxxxxxxxxxxx";

public static void main(String[] args) {

String cityName = "北京";

queryWeather(cityName);

}

/**

* 根据城市名查询天气情况

*

* @param cityName

*/

public static void queryWeather(String cityName) {

Map params = new HashMap<>();//组合参数

params.put("city", cityName);

params.put("key", API_KEY);

String queryParams = urlencode(params);

String response = doGet(API_URL, queryParams);

try {

JSONObject jsonObject = JSONObject.fromObject(response);

int error_code = jsonObject.getInt("error_code");

if (error_code == 0) {

System.out.println("调用接口成功");

JSONObject result = jsonObject.getJSONObject("result");

JSONObject realtime = result.getJSONObject("realtime");

System.out.printf("城市：%s%n", result.getString("city"));

System.out.printf("天气：%s%n", realtime.getString("info"));

System.out.printf("温度：%s%n", realtime.getString("temperature"));

System.out.printf("湿度：%s%n", realtime.getString("humidity"));

System.out.printf("风向：%s%n", realtime.getString("direct"));

System.out.printf("风力：%s%n", realtime.getString("power"));

System.out.printf("空气质量：%s%n", realtime.getString("aqi"));

} else {

System.out.println("调用接口失败：" + jsonObject.getString("reason"));

}

} catch (Exception e) {

e.printStackTrace();

}

}

/**

* get方式的http请求

*

* @param httpUrl 请求地址

* @return 返回结果

*/

public static String doGet(String httpUrl, String queryParams) {

HttpURLConnection connection = null;

InputStream inputStream = null;

BufferedReader bufferedReader = null;

String result = null;// 返回结果字符串

try {

// 创建远程url连接对象

URL url = new URL(new StringBuffer(httpUrl).append("?").append(queryParams).toString());

// 通过远程url连接对象打开一个连接，强转成httpURLConnection类

connection = (HttpURLConnection) url.openConnection();

// 设置连接方式：get

connection.setRequestMethod("GET");

// 设置连接主机服务器的超时时间：15000毫秒

connection.setConnectTimeout(5000);

// 设置读取远程返回的数据时间：60000毫秒

connection.setReadTimeout(6000);

// 发送请求

connection.connect();

// 通过connection连接，获取输入流

if (connection.getResponseCode() == 200) {

inputStream = connection.getInputStream();

// 封装输入流，并指定字符集

bufferedReader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));

// 存放数据

StringBuilder sbf = new StringBuilder();

String temp;

while ((temp = bufferedReader.readLine()) != null) {

sbf.append(temp);

sbf.append(System.getProperty("line.separator"));

}

result = sbf.toString();

}

} catch (IOException e) {

e.printStackTrace();

} finally {

// 关闭资源

if (null != bufferedReader) {

try {

bufferedReader.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (null != inputStream) {

try {

inputStream.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (connection != null) {

connection.disconnect();// 关闭远程连接

}

}

return result;

}

/**

* 将map型转为请求参数型

*

* @param data

* @return

*/

public static String urlencode(Map data) {

StringBuilder sb = new StringBuilder();

for (Map.Entry i : data.entrySet()) {

try {

sb.append(i.getKey()).append("=").append(URLEncoder.encode(i.getValue() + "", "UTF-8")).append("&");

} catch (UnsupportedEncodingException e) {

e.printStackTrace();

}

}

String result = sb.toString();

result = result.substring(0, result.lastIndexOf("&"));

return result;

}

}