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首次接触HttpClient ，参考其他文章中的介绍说 4.3与其他3.x-4.x版本有些大的改变，参考其他大牛的文章
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.http.Consts;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHeaders;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
//java.net.UnknownHostException
public class Test {
/**
* 简单的获取一个HTML页面的内容
*/
public static void getHTML() {
CloseableHttpClient httpClient = null;
try {
// httpClient = HttpClients.createDefault(); //生成一个httpclient对象, 同下代码
httpClient = HttpClientBuilder.create().build();
HttpGet httpGet = new HttpGet("http://www.baidu.com/");
// 配置请求的超时设置
RequestConfig config = RequestConfig.custom().setConnectionRequestTimeout(50).setConnectTimeout(50).build();
httpGet.setConfig(config);
// 配置请求的HEADER部分
httpGet.addHeader(HttpHeaders.ACCEPT, "application/xml");
HttpResponse response = httpClient.execute(httpGet);
System.out.println("状态码：" + response.getStatusLine()); // 返回响应状态信息
// 获取响应消息实体
HttpEntity entity = response.getEntity();
// 获取响应的所有HEADER部分
System.out.println(Arrays.toString(response.getAllHeaders()));
// 判断响应实体是否为空
if (entity != null) {
System.out.println("contentEncoding（内容编码）:" + entity.getContentEncoding());
System.out.println("response content（相应内容）:" + EntityUtils.toString(entity, "UTF-8"));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭或释放资源
try {
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 下载一个文件到本地
*/
public static void downloadFile() {
CloseableHttpClient httpClient = null;
InputStream iStream = null;
FileOutputStream foStream = null;
try {
httpClient = HttpClients.createDefault(); // 生成一个httpclient对象
HttpGet httpGet = new HttpGet("http://ww2.sinaimg.cn/large/9d57a855jw1dqpv9fp4yuj.jpg"); // 传入一张图片的地址
System.out.println("文件正在下载...");
HttpResponse response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
iStream = entity.getContent();
File file = new File("d:/cat.jpg"); // 图片对象
foStream = new FileOutputStream(file);
int i = -1;
byte[] tmp = new byte[1024];
while ((i = iStream.read(tmp)) != -1) {
foStream.write(tmp, 0, i);
}
System.out.println("文件下载完毕...");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
foStream.flush();
foStream.close();
iStream.close();
httpClient.close();
System.out.println("数据流已关闭....");
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* post模拟人人网登陆，人人网的用户名、密码、Action参数可以通过在线人人网页面源代码查看
*/
public static void loginRR() {
String account = "x-rapido@163.com"; // 人人网帐号和密码
String passWord = "x-rapido";
CloseableHttpClient httpClient = null; // 生成一个httpclient对象
HttpPost httpPost = null; // 用于提交登录数据
HttpGet httpGet = null; // 获得登录后的页面
String login_success;// 用于构造上面的HttpGet
httpClient = HttpClients.createDefault();
httpPost = new HttpPost("http://www.renren.com/PLogin.do"); // 人人网登录action
try {
List<NameValuePair> params = new ArrayList<NameValuePair>(); // 封装提交参数
params.add(new BasicNameValuePair("email", account));
params.add(new BasicNameValuePair("password", passWord));
httpPost.setEntity(new UrlEncodedFormEntity(params, Consts.UTF_8)); // 可对参数进行编码
HttpResponse response = httpClient.execute(httpPost); // POST请求,
// 提交登录数据
System.out.println("response.getAllHeaders(): " + Arrays.toString(response.getAllHeaders()));
Header locationHeader = response.getFirstHeader("location"); // 获得跳转的页面
if (locationHeader == null) {
System.out.println("登录不成功，请稍候再试...");
return;
}
login_success = locationHeader.getValue(); // 登录成功后跳转页面
System.out.println("登录成功后的挑战网页名称：" + locationHeader.getName() + ", 地址：" + login_success);
httpGet = new HttpGet(login_success);
HttpResponse response2 = httpClient.execute(httpGet);
// 输出登录成功后的页面
String str = EntityUtils.toString(response2.getEntity());
System.out.println(str);
} catch (Exception e) {
e.printStackTrace();
} finally {
httpPost.abort();
httpGet.abort();
try {
httpClient.close();
System.out.println("完成登录...");
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
getHTML();
// downloadFile();
// loginRR();
}
}打印内容如下示例：
一般并不需要设置很多参数，项目需要即可如下简单配置
/**
* 简单的获取一个HTML页面的内容
*/
public static void getHTML() {
CloseableHttpClient httpClient = null;
try {
// httpClient = HttpClients.createDefault(); //生成一个httpclient对象, 同下代码
httpClient = HttpClientBuilder.create().build();
HttpGet httpGet = new HttpGet("http://www.baidu.com/");
HttpResponse response = httpClient.execute(httpGet);
// 获取响应消息实体
HttpEntity entity = response.getEntity();
// 判断响应实体是否为空
if (entity != null) {
System.out.println("response content（相应内容）:" + EntityUtils.toString(entity, "UTF-8"));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭或释放资源
try {
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}模拟带文件上传的表单提交 http://blog.csdn.net/c_vincente/article/details/17001153
注意：
设置请求的超时验证的2种方式（必须），不然会一直请求下去会造成请求很久无响应
HttpClient3.X和HttpClient4.X的不同超时设置参考文章：http://blog.csdn.net/xiaokui_wingfly/article/details/42595905
（1）RequestConfig config = RequestConfig.custom().setConnectionRequestTimeout(50).setConnectTimeout(50).build(); httpGet.setConfig(config); （2）RequestConfig defaultRequestConfig = RequestConfig.custom().setSocketTimeout(5000).setConnectTimeout(5000) .setConnectionRequestTimeout(5000).setStaleConnectionCheckEnabled(true).build(); CloseableHttpClient httpClient = HttpClients.custom().setDefaultRequestConfig(defaultRequestConfig).build();
比如下面的联接异常处理
/**
* get方式测试服务器联接
*/
public static void getServerData() {
CloseableHttpClient httpClient = null;
try {
RequestConfig defaultRequestConfig = RequestConfig.custom()
.setSocketTimeout(5000).setConnectTimeout(5000)
.setConnectionRequestTimeout(5000)
.setStaleConnectionCheckEnabled(true).build();
httpClient = HttpClients.custom().setDefaultRequestConfig(defaultRequestConfig).build();
HttpGet httpGet = new HttpGet("http://172.25.0.119:7015/DCMapService/servlet/ProxyServlet?type=sg_grid&x=507638.3125000&y=303547.9687500");
HttpResponse response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
// 判断响应实体是否为空
if (entity != null) {
if (entity.toString().trim().equals("")) {
System.out.println("空");
}
System.out.println("server get：" + EntityUtils.toString(entity, "gbk"));
}
}catch (NoRouteToHostException e) {
System.out.println("无网络");
}catch (ConnectTimeoutException e) {
System.out.println("远程服务已断开，请稍候尝试");
}catch (SocketTimeoutException e) {
System.out.println("请求超时，请稍候尝试");
}catch (Exception e) {
e.printStackTrace();
} finally {
try { // 关闭或释放资源
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}HttpClient API地址：http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/package-summary.html
未经允许请勿转载：程序喵 » 【Java】Apache HttpClient 4.3开发指南（三个例子）