出錯信息：
Exception?in?thread?"main"?java.lang.NullPointerException
	at?org.apache.http.impl.client.CloseableHttpClient.determineTarget(CloseableHttpClient.java:91)
	at?org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
	at?org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)
	at?com.imooc.util.WeixinUtil.doGetStr(WeixinUtil.java:35)
	at?com.imooc.util.WeixinUtil.getAssessToken(WeixinUtil.java:80)
	at?com.imooc.test.WeixinTest.main(WeixinTest.java:9)

WeixinTest.java:

package?com.imooc.test;

import?com.imooc.po.AccessToken;
import?com.imooc.util.WeixinUtil;

public?class?WeixinTest?{
	public?static?void?main(String[]?args){
		
		AccessToken?token?=?WeixinUtil.getAccessToken();
		
		System.out.println("票據(jù)："+token.getToken());
		System.out.println("有效時間："+token.getExpiresIn());
	}

}

WeixinUtil.java:

public?static?JSONObject?doGetStr(String?url){
		DefaultHttpClient?httpClient?=?new?DefaultHttpClient();
	//	DefaultHttpClient?httpClient?=?new?DefaultHttpClient();
		HttpGet?httpGet?=?new?HttpGet();
		JSONObject?jsonObject?=?null;
		try?{
			HttpResponse?response?=?httpClient.execute(httpGet);
			HttpEntity?entity=?response.getEntity();
			if(entity?!=null){
				String?result?=?EntityUtils.toString(entity,"UTF-8");
				jsonObject?=?JSONObject.fromObject(result);
			}
		}?catch?(ClientProtocolException?e)?{
			
			e.printStackTrace();
		}?catch?(IOException?e)?{
			
			e.printStackTrace();
		}
		return?jsonObject;
	}
	
	/**
	?*?post請求
	?*?@param?url
	?*?@param?outStr
	?*?@return
	?*/
	
	public?static?JSONObject?doPostStr(String?url,String?outStr){
		DefaultHttpClient?httpClient?=?new?DefaultHttpClient();
		HttpPost?httpPost?=?new?HttpPost(url);
		JSONObject?jsonObject?=?null;
		try?{
			httpPost.setEntity(new?StringEntity(outStr,"UTF-8"));
			HttpResponse?response?=?httpClient.execute(httpPost);
			String?result?=?EntityUtils.toString(response.getEntity(),"UTF-8");
			jsonObject?=?JSONObject.fromObject(result);
		}?catch?(Exception?e)?{
			e.printStackTrace();
		}
		return?jsonObject;
	}
	
	/**
	?*?獲取accessToken
	?*?@return
	?*/
	public?static?AccessToken?getAccessToken()?{
		AccessToken?token?=?new?AccessToken();
		String?url?=?ACCESS_TOKEN_URL.replace("APPID",?APPID).replace("APPSECRET",?APPSECRET);
		JSONObject?jsonObject?=?doGetStr(url);
		if(jsonObject!=null){
			token.setToken(jsonObject.getString("access_token"));
			token.setExpiresIn(jsonObject.getInt("expires_in"));
		}
		return?token;
	}
}

AccessToken.java:

package?com.imooc.po;

public?class?AccessToken?{
	private?String?token;
	private?int?expiresIn;
	public?String?getToken()?{
		return?token;
	}
	public?void?setToken(String?token)?{
		this.token?=?token;
	}
	public?int?getExpiresIn()?{
		return?expiresIn;
	}
	public?void?setExpiresIn(int?expiresIn)?{
		this.expiresIn?=?expiresIn;
	}
}

加載的jar包：