Apache HttpClient4使用教程

大家好，又见面了，我是你们的朋友全栈君。

基于HttpClient 4.5.2

执行GET请求

CloseableHttpClient httpClient = HttpClients.custom()
                .build();
CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.baidu.com"));
System.out.println(EntityUtils.toString(response.getEntity()));

执行POST请求

提交form表单参数

CloseableHttpClient httpClient = HttpClients.custom()
        .build();
HttpPost httpPost = new HttpPost("https://www.explame.com");
List<NameValuePair> formParams = new ArrayList<NameValuePair>();
//表单参数
formParams.add(new BasicNameValuePair("name1", "value1"));
formParams.add(new BasicNameValuePair("name2", "value2"));
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formParams, "utf-8");
httpPost.setEntity(entity);
CloseableHttpResponse response = httpClient.execute(httpPost);
System.out.println(EntityUtils.toString(response.getEntity()));

提交payload参数

CloseableHttpClient httpClient = HttpClients.custom()
            .build();
HttpPost httpPost = new HttpPost("https://www.explame.com");
StringEntity entity = new StringEntity("{\"id\": \"1\"}");
httpPost.setEntity(entity);
CloseableHttpResponse response = httpClient.execute(httpPost);
System.out.println(EntityUtils.toString(response.getEntity()));

post上传文件

CloseableHttpClient httpClient = HttpClients.custom()
        .build();
HttpPost httpPost = new HttpPost("https://www.example.com");
MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
//要上传的文件
multipartEntityBuilder.addBinaryBody("file", new File("temp.txt"));
httpPost.setEntity(multipartEntityBuilder.build());
CloseableHttpResponse response = httpClient.execute(httpPost);
System.out.println(EntityUtils.toString(response.getEntity()));

post提交multipart/form-data类型参数

CloseableHttpClient httpClient = HttpClients.custom()
        .build();
HttpPost httpPost = new HttpPost("https://www.example.com");
MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder.create();
multipartEntityBuilder.addTextBody("username","wycm");
multipartEntityBuilder.addTextBody("passowrd","123");
//文件
multipartEntityBuilder.addBinaryBody("file", new File("temp.txt"));
httpPost.setEntity(multipartEntityBuilder.build());
CloseableHttpResponse response = httpClient.execute(httpPost);
System.out.println(EntityUtils.toString(response.getEntity()));

设置User-Agent

    CloseableHttpClient httpClient = HttpClients.custom()
            .setUserAgent("Mozilla/5.0")
            .build();
    CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.baidu.com"));
    System.out.println(EntityUtils.toString(response.getEntity()));

设置重试处理器
当请求超时, 会自动重试，最多3次

HttpRequestRetryHandler retryHandler = (exception, executionCount, context) -> {
    if (executionCount >= 3) {
        return false;
    }
    if (exception instanceof InterruptedIOException) {
        return true;
    }
    if (exception instanceof UnknownHostException) {
        return true;
    }
    if (exception instanceof ConnectTimeoutException) {
        return true;
    }
    if (exception instanceof SSLException) {
        return true;
    }
    HttpClientContext clientContext = HttpClientContext.adapt(context);
    HttpRequest request = clientContext.getRequest();
    boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
    if (idempotent) {
        return true;
    }
    return false;
};
CloseableHttpClient httpClient = HttpClients.custom()
        .setRetryHandler(retryHandler)
        .build();
httpClient.execute(new HttpGet("https://www.baidu.com"));

重定向策略

HttpClient默认情况
会对302、307的GET和HEAD请求以及所有的303状态码做重定向处理

关闭自动重定向

CloseableHttpClient httpClient = HttpClients.custom()
         //关闭httpclient重定向
        .disableRedirectHandling()
        .build();

POST支持302状态码重定向

CloseableHttpClient httpClient = HttpClients.custom()
    //post 302支持重定向
    .setRedirectStrategy(new LaxRedirectStrategy())
    .build();
CloseableHttpResponse response = httpClient.execute(new HttpPost("https://www.explame.com"));
System.out.println(EntityUtils.toString(response.getEntity()));

定制cookie

方式一：通过addHeader方式设置（不推荐这种方式）
```
    CloseableHttpClient httpClient = HttpClients.custom()
            .build();
    HttpGet httpGet = new HttpGet("http://www.example.com");
    httpGet.addHeader("Cookie", "name=value");
    httpClient.execute(httpGet);
```
由于HttpClient默认会维护cookie状态。如果这个请求response中有Set-Cookie头，那下次请求的时候httpclient默认会把这个Cookie带上。并且会新建一行header。如果再遇到
httpGet.addHeader("Cookie", "name=value");
那么下次请求则会有两行name为Cookie的header。

方式二：通过CookieStore的方式，以浏览器中的cookie为例（推荐）

//此处直接粘贴浏览器cookiefinal String RAW_COOKIES = "name1=value1; name2=value2";final CookieStore cookieStore = new BasicCookieStore();for (String rawCookie : RAW_COOKIES.split("; ")){    String[] s = rawCookie.split("=");    BasicClientCookie cookie = new BasicClientCookie(s[0], s[1]);    cookie.setDomain("baidu.com");    cookie.setPath("/");    cookie.setSecure(false);    cookie.setAttribute("domain", "baidu.com");    Calendar calendar = Calendar.getInstance();    calendar.add(Calendar.DAY_OF_MONTH, +5);    cookie.setExpiryDate(calendar.getTime());    cookieStore.addCookie(cookie);}CloseableHttpClient httpClient = HttpClients.custom()        .setDefaultCookieStore(cookieStore)        .build();httpClient.execute(new HttpGet("https://www.baidu.com"));

这种方式把定制的cookie交给httpclient维护。

cookie管理

方式一：初始化HttpClient时，传入一个自己CookieStore对象

CookieStore cookieStore = new BasicCookieStore();
CloseableHttpClient httpClient = HttpClients.custom()
        .setDefaultCookieStore(cookieStore)
        .build();
httpClient.execute(new HttpGet("https://www.baidu.com"));
//请求一次后,清理cookie再发起一次新的请求
cookieStore.clear();
httpClient.execute(new HttpGet("https://www.baidu.com"));

方式二：每次执行请求的时候传入自己的HttpContext对象

//注:HttpClientContext不是线程安全的，不要多个线程维护一个HttpClientContext
HttpClientContext httpContext = HttpClientContext.create();
CloseableHttpClient httpClient = HttpClients.custom()
        .build();
httpClient.execute(new HttpGet("https://www.baidu.com"), httpContext);
//请求一次后,清理cookie再发起一次新的请求
httpContext.getCookieStore().clear();
httpClient.execute(new HttpGet("https://www.baidu.com"));

http代理的配置

CloseableHttpClient httpClient = HttpClients.custom()
        //设置代理
        .setRoutePlanner(new DefaultProxyRoutePlanner(new HttpHost("localhost", 8888)))
        .build();
CloseableHttpResponse response = httpClient.execute(new HttpGet("http://www.example.com"));
System.out.println(EntityUtils.toString(response.getEntity()));

SSL配置

//默认信任
SSLContext sslContext = SSLContexts.custom()
        .loadTrustMaterial(KeyStore.getInstance(KeyStore.getDefaultType())
                , (chain, authType) -> true).build();
Registry<ConnectionSocketFactory> socketFactoryRegistry =
        RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", new SocketProxyPlainConnectionSocketFactory())
                .register("https", new SocketProxySSLConnectionSocketFactory(sslContext))
                .build();
CloseableHttpClient httpClient = HttpClients.custom()
        .setConnectionManager(new PoolingHttpClientConnectionManager(socketFactoryRegistry))
        .build();
HttpClientContext httpClientContext = HttpClientContext.create();
httpClientContext.setAttribute("socks.address", new InetSocketAddress("127.0.0.1", 1086));
CloseableHttpResponse response = httpClient.execute(new HttpGet("https://httpbin.org/ip"), httpClientContext);
System.out.println(EntityUtils.toString(response.getEntity()));

socket代理配置

static class SocketProxyPlainConnectionSocketFactory extends PlainConnectionSocketFactory{
    @Override
    public Socket createSocket(final HttpContext context) {
        InetSocketAddress socksAddr = (InetSocketAddress) context.getAttribute("socks.address");
        if (socksAddr != null){
            Proxy proxy = new Proxy(Proxy.Type.SOCKS, socksAddr);
            return new Socket(proxy);
        } else {
            return new Socket();
        }
    }
}
static class SocketProxySSLConnectionSocketFactory extends SSLConnectionSocketFactory {
    public SocketProxySSLConnectionSocketFactory(final SSLContext sslContext) {
        super(sslContext, NoopHostnameVerifier.INSTANCE);
    }

    @Override
    public Socket createSocket(final HttpContext context) {
        InetSocketAddress socksAddr = (InetSocketAddress) context.getAttribute("socks.address");
        if (socksAddr != null){
            Proxy proxy = new Proxy(Proxy.Type.SOCKS, socksAddr);
            return new Socket(proxy);
        } else {
            return new Socket();
        }
    }

}
/**
 * socket代理配置
 */
public static void socketProxy() throws Exception {
    //默认信任
    SSLContext sslContext = SSLContexts.custom()
            .loadTrustMaterial(KeyStore.getInstance(KeyStore.getDefaultType())
                    , (X509Certificate[] chain, String authType) -> true).build();
    Registry<ConnectionSocketFactory> socketFactoryRegistry =
            RegistryBuilder.<ConnectionSocketFactory>create()
                    .register("http", new SocketProxyPlainConnectionSocketFactory())
                    .register("https", new SocketProxySSLConnectionSocketFactory(sslContext))
                    .build();
    CloseableHttpClient httpClient = HttpClients.custom()
            .setConnectionManager(new PoolingHttpClientConnectionManager(socketFactoryRegistry))
            .build();
    HttpClientContext httpClientContext = HttpClientContext.create();
    httpClientContext.setAttribute("socks.address", new InetSocketAddress("127.0.0.1", 1086));
    CloseableHttpResponse response = httpClient.execute(new HttpGet("https://httpbin.org/ip"), httpClientContext);
    System.out.println(EntityUtils.toString(response.getEntity()));
}

下载文件

CloseableHttpClient httpClient = HttpClients.custom().build();
CloseableHttpResponse response = httpClient.execute(new HttpGet("https://www.example.com"));
InputStream is = response.getEntity().getContent();
Files.copy(is, new File("temp.png").toPath(), StandardCopyOption.REPLACE_EXISTING);

最后

完整Demo源码下载地址:https://github.com/wycm/HttpClientDemo

版权声明
作者：wycm
出处：https://blog.csdn.net/vwycm/article/details/88638996
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