HttpClient 重定向 302

雨点打透心脏的1/2处 2022-05-10 09:38 352阅读 0赞

使用HttpClient访问http地址，有时候会报302错误。

通过上网搜索，发现问题所在，报302是因为访问的http地址在服务端做了访问重定向，需要请求重定向后的URI。

1.简单实例，http访问返回302，此时需要获取重定向地址，继续进行重定向访问，以获取最终结果：

public class TestLogin {
        public static void main(String args[]) {
            try {
                HttpClient client = HttpClients.createDefault();
                login(client);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    
        public static void login(HttpClient client) throws Exception {
            final String APPLICATION_JSON = "application/json";
            final String CONTENT_TYPE_TEXT_JSON = "text/json";
    
    
            String url = "http://172.16.30.208:8092/svc/login";
            String js = "{\"username\":\"13800000002\",\"password\":\"123456\"}";
    
            HttpPost httpPost = new HttpPost(url);
            httpPost.setHeader("Content-Type", "application/json;charset=UTF-8");
    
    
            StringEntity se = new StringEntity(js);
            se.setContentType(CONTENT_TYPE_TEXT_JSON);
    
            httpPost.setEntity(se);
    
            HttpResponse response = null;
    
            response = client.execute(httpPost);
    
            //----------判断是否重定向开始
            int code = response.getStatusLine().getStatusCode();
            String newuri = "";
            if (code == 302) {
                Header header = response.getFirstHeader("location"); // 跳转的目标地址是在 HTTP-HEAD 中的
                newuri = header.getValue(); // 这就是跳转后的地址，再向这个地址发出新申请，以便得到跳转后的信息是啥。
                System.out.println(newuri);
                System.out.println(code);
    
                httpPost = new HttpPost(newuri);
                httpPost.setHeader("Content-Type", "application/json;charset=UTF-8");
    
                se = new StringEntity(js);
                se.setContentType(CONTENT_TYPE_TEXT_JSON);
    
                httpPost.setEntity(se);
    
                response = client.execute(httpPost);
                code = response.getStatusLine().getStatusCode();
                System.out.println("login" + code);
            }
    
            //------------重定向结束
            HttpEntity entity = null;
            entity = response.getEntity();
            String s2 = EntityUtils.toString(entity, "UTF-8");
            System.out.println(s2);
    
    
        }
    }

2.复杂实例，来自网络：

需要引导用户打开授权页面进行授权

1). 直接获取数据，传递用户账号；

2).  没有登陆直接去访问会跳转到登陆页面；

3). 登陆了之后，会有个授权页面，需要手动去点击授权按钮才真正跳转；

/**
     * <pre>
     * 模拟需要登陆之后才能访问第三方网站
     * 并且需要一些人工参与的操作
     * </pre>
     */
    public class Test {
    
        private String userName = "我是用户名";
    
        private String password = "我是密码";
    
        public void loginNext() throws IOException {
    
            BasicCookieStore cookieStore = new BasicCookieStore();
            // 全局用这一个httpClient对象模拟真实的一个浏览器中操作
            CloseableHttpClient httpClient = HttpClients.custom().setDefaultCookieStore(cookieStore).build();
            try {
                // 模拟用户登录
                HttpPost httpLogin = new HttpPost("xxxxxxxxxxxxxx/index.php/auth/auth/login");// 指向一个没有验证码的登录页面
                List<NameValuePair> nvps = new ArrayList<>();
                nvps.add(new BasicNameValuePair("username", userName));// 用户名对应的key
                nvps.add(new BasicNameValuePair("password", MD5Coder.md5Encode(password)));// 密码对应的key
                httpLogin.setEntity(new UrlEncodedFormEntity(nvps));
                CloseableHttpResponse respLogin = httpClient.execute(httpLogin);
                try {
                    HttpEntity entity = respLogin.getEntity();
                    out.println("respLogin------------>>" + respLogin.toString());
                    out.println("Login form get: " + respLogin.getStatusLine());
                    EntityUtils.consume(entity);
                    out.println("Initial set of cookies:");
                    List<Cookie> cookies = cookieStore.getCookies();
                    if (cookies.isEmpty()) {
                        out.println("None");
                    } else {
                        for (int i = 0; i < cookies.size(); i++) {
                            out.println("Cookie-" + i + "==" + cookies.get(i).toString());
                        }
                    }
                } finally {
                    respLogin.close();
                }
    
                // 利用会话保持，继续访问目标地址
                HttpGet httpGetAuth = new HttpGet("xxxxxxxxxxxxxxx/index.php/Auth/Auth/auth?app_id=xxxxxx&redirect_uri=回调地址&response_type=code");
                CloseableHttpResponse respAuth = httpClient.execute(httpGetAuth);
                String entityAuthStr = "";
                try {
                    out.println(respAuth.getStatusLine());
                    HttpEntity entityAuth = respAuth.getEntity();
                    entityAuthStr = EntityUtils.toString(entityAuth);
                    out.println("get Auth cookies:");
                    List<Cookie> cookies = cookieStore.getCookies();
                    if (cookies.isEmpty()) {
                        out.println("None");
                    } else {
                        for (int i = 0; i < cookies.size(); i++) {
                            out.println("- " + cookies.get(i).toString());
                        }
                    }
                    out.println("访问目标地址的结果--------------------->>" + entityAuthStr);//把结果打印出来看一下
                    EntityUtils.consume(entityAuth);
                } finally {
                    respAuth.close();
                }
                // 解析登陆之后访问目标地址的html页面 获取目标form表单元素
                Document doc = Jsoup.parseBodyFragment(entityAuthStr);
                String title = doc.title();
                out.println("title-------->>" + title);
                Element element = doc.body();
                Elements form = element.select("[name='authForm']");// 授权的form表单
                out.println(form);
                String actionUrl = form.attr("action");
                String app_id = element.select("[name='app_id']").val();
                String redirect_uri = element.select("[name='redirect_uri']").val();
                String state = element.select("[name='state']").val();
                String key = element.select("[name='key']").val();
                String format = element.select("[name='format']").val();
    
                // 利用会话保持，继续模拟点击授权按钮 提交form表单
                HttpPost httpPostGetCode = new HttpPost(actionUrl);
                List<NameValuePair> nvps2 = new ArrayList<>();
                nvps2.add(new BasicNameValuePair("app_id", app_id));
                nvps2.add(new BasicNameValuePair("redirect_uri", redirect_uri));
                nvps2.add(new BasicNameValuePair("state", state));
                nvps2.add(new BasicNameValuePair("key", key));
                nvps2.add(new BasicNameValuePair("format", format));
                httpPostGetCode.setEntity(new UrlEncodedFormEntity(nvps2));
                CloseableHttpResponse respGetCode = httpClient.execute(httpPostGetCode);
                try {
                    HttpEntity entityGetCode = respGetCode.getEntity();
                    out.println("respAuth------------>>" + respGetCode.toString());
                    // 最终目的 获取Location中的url中的某一值
                    Header location = respGetCode.getFirstHeader("Location");
                    out.println("location------------>>" + location.getValue());
                    EntityUtils.consume(entityGetCode);
                } finally {
                    respGetCode.close();
                }
            } finally {
                httpClient.close();
            }
        }
    }