封裝ResponseHandler定製處理HttpResponse

HttpClient是一個高效的、功能豐富的HTTP客戶端編程工具包，以編程的方式經過API傳輸和接收HTTP消息。返回的HttpResponse請求結果經過ResponseHandler<T>處理，能夠定製封裝功能邏輯。

ResponseHandler<T>是httpclient包內提供的接口，實現函數handleResponse()處理HTTP返回結果：

package org.apache.http.client;

import java.io.IOException;
import org.apache.http.HttpResponse;

public interface ResponseHandler<T> {
    T handleResponse(HttpResponse var1) throws ClientProtocolException, IOException;
}

分享封裝的4個HTTP返回結果請求類，簡化處理邏輯，提升開發效率。

代碼文件	HTTP返回結果類型
RespStr.java	返回字符串
RespJsonObj.java	返回JSONObject
RespJsonArr.java	返回JSONArray
RespFile.java	返回二進制文件

 

l 代碼

Github下載：https://github.com/jextop/StarterApi/

 

l RespStr.java：讀取HttpResponse返回的內容，格式化爲String字符串

- 調用httpResponse.getEntiry()獲取返回結果

- 調用ContentType.get()獲取內容類型

- 調用ContentType.getCharset()獲取編碼格式

- 調用EntityUtils.toString()將返回結果格式化爲字符串

public class RespStr implements ResponseHandler<String> {
    @Override
    public String handleResponse(HttpResponse httpResponse) throws ClientProtocolException, IOException {
        HttpEntity entity = httpResponse.getEntity();
        ContentType contentType = ContentType.getOrDefault(entity);
        Charset charset = contentType.getCharset();
        return EntityUtils.toString(entity, charset);
    }
}

 

l RespJsonObj.java：在返回結果爲JSON對象時，轉換成JSONObject返回

public class RespJsonObj implements ResponseHandler<JSONObject> {
    @Override
    public JSONObject handleResponse(HttpResponse resp) throws ClientProtocolException, IOException {
        HttpEntity entity = resp.getEntity();
        ContentType contentType = ContentType.getOrDefault(entity);
        Charset charset = contentType.getCharset();
        String jsonStr = EntityUtils.toString(entity, charset);

        // parse JSON object
        return JsonUtil.parseObj(jsonStr);
    }
}

 

l RespJsonArr.java：將HTTP請求返回結果轉換成JSONArray返回

public class RespJsonArr implements ResponseHandler<JSONArray> {
    @Override
    public JSONArray handleResponse(HttpResponse resp) throws ClientProtocolException, IOException {
        HttpEntity entity = resp.getEntity();
        ContentType contentType = ContentType.getOrDefault(entity);
        Charset charset = contentType.getCharset();
        String jsonStr = EntityUtils.toString(entity, charset);

        // parse JSON array
        return JsonUtil.parseArr(jsonStr);
    }
}

 

l RespFile.java：在HTTP返回二進制文件時，從Entity中讀取二進制內容，並可從Header中獲取文件名稱。

public class RespFile implements ResponseHandler<byte[]> {
    private static final String fileNameFlag = "attachment;fileName=";

    private byte[] bytes;
    private String fileName;

    public byte[] getBytes() {
        return bytes;
    }

    public String getFileName() {
        return fileName;
    }

    @Override
    public byte[] handleResponse(HttpResponse response) throws ClientProtocolException, IOException {
        // Header: Content-Disposition: attachment;fileName=abc.txt
        Header header = response.getFirstHeader("Content-Disposition");
        String headerValue = header.getValue();
        if (headerValue.startsWith(fileNameFlag)) {
            fileName = headerValue.substring(fileNameFlag.length(), headerValue.length());
        }

        HttpEntity entity = response.getEntity();
        bytes = EntityUtils.toByteArray(entity);
        return bytes;
    }
}

 

l HttpService中使用RespStr處理HttpResponse示例：

@Service
public class HttpService {
    @Autowired
    private HttpClient httpClient;

    public <T> T sendRequest(HttpRequestBase httpRequest, ResponseHandler<T> handler) {
        try {
            return httpClient.execute(httpRequest, handler);
        } catch (ClientProtocolException e) {
            LogUtil.error("Error when sendRequest", e.getMessage());
        } catch (IOException e) {
            LogUtil.error("Error when sendRequest", e.getMessage());
        }
        return null;
    }

    public <T> T sendHttpGet(String url, ResponseHandler<T> handler) {
        return sendRequest(new HttpGet(url), handler);
    }

    public String sendHttpGet(String url) {
        return sendHttpGet(url, new RespStr());
    }
}