02_HttpClient_Get请求

【实例1. GET请求百度（乱码）】

/**
 * Http GET请求百度，但是返回乱码
 */
public static void main(String[] args) throws Exception {
    //创建一个默认的HttpClient类
    CloseableHttpClient  httpclient=HttpClients.createDefault();
    //设置Http连接方式为get，访问的URL为"http://www.baidu.com"
    HttpGet httpGet=new HttpGet("http://www.baidu.com");
    //得到返回的response对象
    HttpResponse response=httpclient.execute(httpGet);
    //得到response里面的实体信息
    HttpEntity entity=response.getEntity();
    //利用EntityUtils工具类将实体信息转换为字符串
    String html=EntityUtils.toString(entity);
    //打印
    System.out.println(html);
    //关闭链接
    httpclient.close();
}

【实例2.Get请求百度，解决乱码问题】

public static void main(String[] args) throws Exception {
    //创建一个默认的HttpClient类
    CloseableHttpClient  httpclient=HttpClients.createDefault();
    //设置Http连接方式为get，访问的URL为"http://www.baidu.com"
    HttpGet httpGet=new HttpGet("http://www.baidu.com");
    //得到返回的response对象
    HttpResponse response=httpclient.execute(httpGet);
    //得到response里面的实体信息
    HttpEntity entity=response.getEntity();
    //利用EntityUtils工具类将实体信息转换为字符串
    String html=EntityUtils.toString(entity,"UTF-8");
    //打印
    System.out.println(html);
    //关闭链接
    httpclient.close();
}

【实例3.带各种消息头的GET请求】

@Test
public void testRequestHeader() throws ClientProtocolException, IOException{
    CloseableHttpClient  httpclient=HttpClients.createDefault();
    HttpGet httpGet=new HttpGet("http://download.csdn.net/my/uploads");  //访问CSDN的"下载资源"页面
    //带上cookie请求消息头
    httpGet.setHeader("cookie", "uuid_tt_dd=439312343077018427_20160728; bdshare_firstime=2345017309443; _JQCMT_ifcookie=1; ********************");  //登录之后用浏览器获取对应给的Cookie
    httpGet.setHeader("Host","download.csdn.net");
    httpGet.setHeader("Referer","http://download.csdn.net/my/uploads");
    HttpResponse response=httpclient.execute(httpGet);
    HttpEntity entity=response.getEntity();
    String html=EntityUtils.toString(entity,"UTF-8");
    System.out.println(html);
    httpclient.close();
}

【实例4. 获取Get请求百度后 响应页面的各个信息（状态行、消息头、响应正文）】

@Test
public void test01() throws Exception{
    CloseableHttpClient  httpclient=HttpClients.createDefault();
    HttpGet httpGet=new HttpGet("http://www.baidu.com");
    HttpResponse response=httpclient.execute(httpGet);

    //响应的response对象
    System.out.println("【 响应对象  】 \n"+response);
    //响应的状态行
    System.out.println("【 响应的状态行 】 \n"+response.getStatusLine());
    //获得响应状态行的状态码
    System.out.println("【 响应的状态行的状态码 】 \n"+response.getStatusLine().getStatusCode());

    //响应实体
    System.out.println("【 响应实体 】 \n"+response.getEntity());

    //遍历响应所有的消息头
    System.out.println("=====================【 遍历打印所有的消息头】======================");
    Header[] headers=response.getAllHeaders();
    for(Header header:headers){
        System.out.println(header.getName()+"======="+header.getValue());
    }

    //获取特定的响应头
    System.out.println("=====================【 获取特定响应头(Server) 】======================\n"+response.getHeaders("Server")[].getName()+"-----------------"+response.getHeaders("Server")[].getValue());

    //将响应的页面转化成字符串
    System.out.println("=====================【 将响应的页面转化成字符串 】=========================");
    HttpEntity entity=response.getEntity();
    String html=EntityUtils.toString(entity,"UTF-8");
    System.out.println(html);

    //关闭连接
    httpclient.close();
}

[ 运行结果 ]

【实例5.利用URIBuilder创建带参数的URI的方式一（常用）】

/**
 * 利用URIBuilder创建带参数的URI
 * 例子：搜狗查询 关键字搜索"HigginCui"
 */
@Test
public void testURI() throws Exception{
    CloseableHttpClient  httpclient=HttpClients.createDefault();

    URIBuilder uriBuilder=new URIBuilder("http://www.sogou.com/web");
    uriBuilder.setParameter("query", "HigginCui");  //其实这里也可以用uriBuilder.addParameter("query","HigginCui")来代替，两者有一点区别，具体看源码
    uriBuilder.setParameter("ie", "utf-8");
    URI uri=uriBuilder.build();
    System.out.println("uri=="+uri);   //uri==http://www.sogou.com/web?query=HigginCui&ie=utf-8

    HttpGet httpGet=new HttpGet(uri);
    HttpResponse response=httpclient.execute(httpGet);

    //将响应的页面转化成字符串
    System.out.println("=====================【 将响应的页面转化成字符串 】=========================");
    HttpEntity entity=response.getEntity();
    String html=EntityUtils.toString(entity,"UTF-8");
    System.out.println(html);
    httpclient.close();
}

[ 浏览器用这个URI去进行搜索的实际效果 ]

【实例6.利用URIBuilder创建带参数的URI的方式二】

/**
 * 利用URIBuilder创建带参数的URI的第二种方式
 * 例子：搜狗查询 关键字搜索"HigginCui"
 */
@Test
public void testURI2() throws Exception{
    CloseableHttpClient  httpclient=HttpClients.createDefault();

    URIBuilder uriBuilder=new URIBuilder("http://www.sogou.com/web");

    List<NameValuePair> valuePairs=new ArrayList<NameValuePair>();
    valuePairs.add(new BasicNameValuePair("query", "HigginCui"));
    valuePairs.add(new BasicNameValuePair("ie", "utf-8"));
    uriBuilder.addParameters(valuePairs);

    URI uri=uriBuilder.build();
    System.out.println("uri=="+uri);   //uri==http://www.sogou.com/web?query=HigginCui&ie=utf-8

    HttpGet httpGet=new HttpGet(uri);
    HttpResponse response=httpclient.execute(httpGet);

    //将响应的页面转化成字符串
    System.out.println("=====================【 将响应的页面转化成字符串 】=========================");
    HttpEntity entity=response.getEntity();
    String html=EntityUtils.toString(entity,"UTF-8");
    System.out.println(html);
    httpclient.close();
}

【实例7.关于RequestConfig类（HTTPRequest的配置信息）】

Test
public void testRequestConfig() throws ClientProtocolException, IOException{
    CloseableHttpClient  httpclient=HttpClients.createDefault();

    HttpGet httpGet=new  HttpGet("http://www.baidu.com");

    /**设置请求和传输的超时时间**/
    RequestConfig requestConfig=RequestConfig.custom()
                                .setConnectionRequestTimeout()  //设置从连接池获取连接的超时时间
                                .setConnectTimeout()　　　　　　  //设置连接远端服务器的超时时间
                                .setSocketTimeout()　　　　　　　 //设置从远端服务器上传输数据回来的超时时间
                                .build();
    httpGet.setConfig(requestConfig);  //将配置requestConfig设置到HttpGet请求中

    CloseableHttpResponse response=httpclient.execute(httpGet);

    response.close();
    httpclient.close();
}

【实例8.设置代理，利用Fiddler捕获本地的请求】

@Test
public void testRequestConfigGet() throws ClientProtocolException, IOException{
    CloseableHttpClient  httpclient=HttpClients.createDefault();

    HttpGet httpGet=new  HttpGet("http://www.baidu.com");

    /**设置请求和传输的超时时间**/
    RequestConfig.Builder builder=RequestConfig.custom()
                                .setConnectionRequestTimeout()
                                .setConnectTimeout()
                                .setSocketTimeout();
 String proxy="127.0.0.1:8888";              //本地Fiddler代理监听的端口
    builder.setProxy(HttpHost.create(proxy));  //设置代理
    RequestConfig requestConfig=builder.build();  

    httpGet.setConfig(requestConfig);  //将配置requestConfig设置到HttpGet请求中

    //带上cookie请求消息头
    httpGet.setHeader("Cookie", "***************HigginCui***************");
    httpGet.setHeader("Accept","*/*");

    CloseableHttpResponse response=httpclient.execute(httpGet);

    response.close();
    httpclient.close();
}

[ 运行之后的fiddler捕获的内容 ]