前言

近期研究如何利用java代码如何获取其他系统中所需的数据，自己总结的方法如下：

1.工具类代码

 /**
     * <pre>
     * 方法体说明：向远程接口发起请求，返回字符串类型结果
     * @param url 接口地址
     * @param requestMethod 请求类型
     * @param params 传递参数
     * @return String 返回结果
     * </pre>
     */
    public static String httpRequestToString(String url, String requestMethod,
                                 Map<String, String> params, String ...auth){
        //接口返回结果
        String requestResult = null;
        try {
            String parameters = "";
            boolean hasParams = false;
            //将参数集合拼接成特定格式，如name=zhangsan&age=24
            for(String key : params.keySet()){
                String value = URLEncoder.encode(params.get(key), "UTF-8");
                parameters += key +"="+ value +"&";
                hasParams = true;
            }
            if(hasParams){
                parameters = parameters.substring(0, parameters.length()-1);
            }
            //是否为GET方式请求
            boolean isGet = "get".equalsIgnoreCase(requestMethod);
            boolean isPost = "post".equalsIgnoreCase(requestMethod);
            boolean isPut = "put".equalsIgnoreCase(requestMethod);
            boolean isDelete = "delete".equalsIgnoreCase(requestMethod);

            //创建HttpClient连接对象
            DefaultHttpClient client = new DefaultHttpClient();
            HttpRequestBase method = null;
            if(isGet){
                url += "?" + parameters;
                method = new HttpGet(url);
            }else if(isPost){
                method = new HttpPost(url);
                HttpPost postMethod = (HttpPost) method;
                StringEntity entity = new StringEntity(parameters);
                postMethod.setEntity(entity);
            }else if(isPut){
                method = new HttpPut(url);
                HttpPut putMethod = (HttpPut) method;
                StringEntity entity = new StringEntity(parameters);
                putMethod.setEntity(entity);
            }else if(isDelete){
                url += "?" + parameters;
                method = new HttpDelete(url);
            }
            method.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 6000);
            //设置参数内容类型
            method.addHeader("Content-Type","application/x-www-form-urlencoded");
            //httpClient本地上下文
            HttpClientContext context = null;
            if(!(auth==null || auth.length==0)){
                String username = auth[0];
                String password = auth[1];
                UsernamePasswordCredentials credt = new UsernamePasswordCredentials(username,password);
                //凭据提供器
                CredentialsProvider provider = new BasicCredentialsProvider();
                //凭据的匹配范围
                provider.setCredentials(AuthScope.ANY, credt);
                context = HttpClientContext.create();
                context.setCredentialsProvider(provider);
            }
            //访问接口，返回状态码
            HttpResponse response = client.execute(method, context);
            //返回状态码200，则访问接口成功
            if(response.getStatusLine().getStatusCode()==200){
                requestResult = EntityUtils.toString(response.getEntity());
            }
            client.close();
        }catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }catch (IOException e) {
            e.printStackTrace();
        }
        return requestResult;
    }

2.测试代码

public static void main(String[] args) {
        //url中获取的登录的接口
        String url ="https://●●●●●●●●●●●●/login/validate.do";
        Map<String, String> params = new HashMap<>();
        // 用户名
        params.put("username","LZZHXF");
        // 密码
        params.put("password","●●●●●●●");
        // 是否记住密码
        params.put("isRemenber","true");
        //  根据用户名、密码调用登录接口返回token
        String string = httpRequestToString(url, "post", params);
        System.out.println(string);
    }

返回如下图所示：