封装ResponseHandler定制处理HttpResponse

HttpClient是一个高效的、功能丰富的HTTP客户端编程工具包，以编程的方式通过API传输和接收HTTP消息。返回的HttpResponse请求结果通过ResponseHandler处理，可以定制封装功能逻辑。

ResponseHandler是httpclient包内提供的接口，实现函数handleResponse()处理HTTP返回结果：

package org.apache.http.client;

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

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

分享封装的4个HTTP返回结果请求类，简化处理逻辑，提高开发效率。

代码文件	HTTP返回结果类型
RespStr.java	返回字符串
RespJsonObj.java	返回JSONObject
RespJsonArr.java	返回JSONArray
RespFile.java	返回二进制文件

 

l 代码

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

 

l RespStr.java：读取HttpResponse返回的内容，格式化为String字符串

- 调用httpResponse.getEntiry()获取返回结果

- 调用ContentType.get()获取内容类型

- 调用ContentType.getCharset()获取编码格式

- 调用EntityUtils.toString()将返回结果格式化为字符串

public class RespStr implements ResponseHandler {
    @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：在返回结果为JSON对象时，转换成JSONObject返回

public class RespJsonObj implements ResponseHandler {
    @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：将HTTP请求返回结果转换成JSONArray返回

public class RespJsonArr implements ResponseHandler {
    @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返回二进制文件时，从Entity中读取二进制内容，并可从Header中获取文件名称。

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处理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());
    }
}