HttpClient请求及下载文件

发表于 分类于
HttpClient 是Apache Jakarta Common 下的子项目，可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包，并且它支持 HTTP 协议最新的版本和建议。

添加maven依赖

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<dependency>
	<artifactId>httpclient</artifactId>
	<groupId>org.apache.httpcomponents</groupId>
	<version>4.4.1</version>
</dependency>
<dependency>
	<artifactId>httpcore</artifactId>
	<groupId>org.apache.httpcomponents</groupId>
	<version>4.4.1</version>
</dependency>

HttpClient发送Get请求

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import java.io.IOException;
import java.net.HttpURLConnection;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

/**
 * @author lm
 *
 */
public class SimpleHttpGeter {

  public String doGet(String url) throws IOException {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpGet httpGet = new HttpGet(url);
    CloseableHttpResponse response = httpclient.execute(httpGet);
    try {
      if (response != null && response.getStatusLine().getStatusCode() == HttpURLConnection.HTTP_OK) {
        return EntityUtils.toString(response.getEntity());
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      response.close();
      httpclient.close();
    }
    return null;
  }

  public String doGet(String url, String[] paramNames, String[] paramValues) throws IOException {
    StringBuilder sb = new StringBuilder(url);
    sb.append("?");
    for (int i = 0; i < paramNames.length; i++) {
      sb.append(paramNames[i] + "=" + paramValues[i] + "&");
    }
    sb.deleteCharAt(sb.length() - 1);
    return doGet(sb.toString());
  }

}

HttpClient发送Post请求

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import java.io.IOException;
import java.net.HttpURLConnection;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

/**
 * @author lm
 *
 */
public class SimpleHttpPoster {

  public String doPost(String url) throws IOException {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost(url);
    CloseableHttpResponse response = httpclient.execute(httpPost);
    try {
      if (response != null && response.getStatusLine().getStatusCode() == HttpURLConnection.HTTP_OK) {
        return EntityUtils.toString(response.getEntity());
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      response.close();
      httpclient.close();
    }
    return null;
  }

  public String doPost(String url, String[] paramNames, String[] paramValues) throws IOException {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost(url);
    List<NameValuePair> nvps = new ArrayList<NameValuePair>();
    // 迭代参数
    for (int i = 0; i < paramNames.length; i++) {
      nvps.add(new BasicNameValuePair(paramNames[i], paramValues[i]));
    }
    httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));
    CloseableHttpResponse response = httpclient.execute(httpPost);
    try {
      if (response != null && response.getStatusLine().getStatusCode() == HttpURLConnection.HTTP_OK) {
        return EntityUtils.toString(response.getEntity());
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      response.close();
      httpclient.close();
    }
    return null;
  }

  public String doBody(String url, String parmas) throws IOException {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpPost post = new HttpPost(url);
    post.addHeader("Content-type", "application/json; charset=utf-8");
    post.setHeader("Accept", "application/json");
    post.setEntity(new StringEntity(parmas, Charset.forName("utf-8")));
    CloseableHttpResponse response = httpclient.execute(post);
    try {
      if (response != null && response.getStatusLine().getStatusCode() == HttpURLConnection.HTTP_OK) {
        return EntityUtils.toString(response.getEntity());
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      response.close();
      httpclient.close();
    }
    return null;
  }

}

HttpClient下载文件

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import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.http.StatusLine;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

/**
 * @author lm
 *
 */
public class HttpDownload {
  private static final int WRITE_SIZE = 4096;

  public boolean download(String url, String filePath) throws IOException {
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse httpResponse = null;
    FileOutputStream outputStream = null;
    try {
      httpClient = HttpClients.createDefault();
      HttpGet httpGet = new HttpGet(url);
      httpResponse = httpClient.execute(httpGet);
      StatusLine statusLine = httpResponse.getStatusLine();
      if (statusLine.getStatusCode() == 200) {
        File file = new File(filePath);
        outputStream = new FileOutputStream(file);
        InputStream inputStream = httpResponse.getEntity().getContent();
        byte buff[] = new byte[WRITE_SIZE];
        int counts = 0;
        while ((counts = inputStream.read(buff)) != -1) {
          outputStream.write(buff, 0, counts);
        }
        outputStream.flush();
      } else {
        return false;
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw e;
    } finally {
      if (outputStream != null) {
        outputStream.close();
      }
      if (httpClient != null) {
        httpClient.close();
      }
      if (httpResponse != null) {
        httpResponse.close();
      }
    }
    return true;
  }

}

不使用HttpClient下载文件

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import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpDownload {

  public static void downloadFile(String url, String filePath, String method) throws Exception {
    FileOutputStream fileOut = null;
    HttpURLConnection conn = null;
    InputStream inputStream = null;
    try {
      // 建立链接
      URL httpUrl = new URL(url);
      conn = (HttpURLConnection) httpUrl.openConnection();
      // 以Post方式提交表单，默认get方式
      conn.setRequestMethod(method);
      conn.setDoInput(true);
      conn.setDoOutput(true);
      // post方式不能使用缓存
      conn.setUseCaches(false);
      // 连接指定的资源
      conn.connect();
      // 获取网络输入流
      inputStream = conn.getInputStream();
      BufferedInputStream bis = new BufferedInputStream(inputStream);
      // 写入到文件（注意文件保存路径的后面一定要加上文件的名称）
      fileOut = new FileOutputStream(filePath);
      BufferedOutputStream bos = new BufferedOutputStream(fileOut);
      byte[] buf = new byte[4096];
      int length = bis.read(buf);
      // 保存文件
      while (length != -1) {
        bos.write(buf, 0, length);
        length = bis.read(buf);
      }
      bos.close();
      bis.close();
      conn.disconnect();
    } catch (Exception e) {
      e.printStackTrace();
      throw e;
    }
  }

}