SpringBoot中Filter的使用之跨系统调用

港控/mmm° 2022-05-13 10:50 96阅读 0赞

# **SpringBoot中Filter的使用之跨系统调用** #

### **目的** ###

*  有两个系统，分别是系统A和系统B；现在有这么个需求，就是在A系统中用到B系统的数据。

### **解决方案** ###

*  这时候你可能想到直接调用B系统的接口来获取数据
    
     *  但是你想过没有，如果在A系统中调用B系统的东西，将会发生跨域问题
 *  明确跨域问题是发生在浏览器中的，解决方案可以在A系统中加入对B系统的URL的过滤，具体设计如下图
    
     *  ![0SFH4dX.png][]

### **具体的代码中实现** ###

*  过滤器代码

@Component @WebFilter(filterName = "TransFilter", urlPatterns = {"/kungfupeng/sysA/transToB/*"}) public class TransFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest httpRequest = (HttpServletRequest) request; HttpServletResponseWrapper httpResponse = new HttpServletResponseWrapper((HttpServletResponse) response); //获取参数映射键值对 Map<String, String[]> parameterMap = httpRequest.getParameterMap(); //组装新的参数键值映射对-----start----- Map<String, String> newParams = new HashMap<String, String>(); if (parameterMap != null && parameterMap.size() != 0) { for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) { //这里的参数可以根据需求来定【这里默认为一key一value】 newParams.put(entry.getKey(), entry.getValue()[0]); } } //组装新的参数键值映射对------end------ //获取需要地址转换的路径 String path = httpRequest.getRequestURI(); //做校验，是否是满足地址转换的条件 if (path != null && path.contains("/sysA/transToB/")) { path = path.replace("/sysA/transToB/", "/sysB/"); //拼接访问B系统的地址 path = "http://kungfupeng" + path; //利用OkHttp工具类来进行对B系统的访问【这里的参数一定记得传递过去】 String s = OkHttpUtils.get(path, newParams); //返回的结果 System.out.println("返回字符串【" + s + "】"); //设置返回内容编码格式 httpResponse.setHeader("Content-type", "text/html; charset=utf-8"); //从系统A进行返回 httpResponse.getWriter().write(s); } else { chain.doFilter(request, response); } return; } @Override public void destroy() { } }

### **补充【OkHttp的工具类】** ###

*  pom文件的依赖配置
    
     
    
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>3.9.1</version>
        </dependency>
        <dependency>
            <groupId>com.squareup.okio</groupId>
            <artifactId>okio</artifactId>
            <version>1.14.0</version>
        </dependency>
 *  Okhttp工具类
    
     
    
        public class OkHttpUtils {
            public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
        
            public OkHttpUtils() {
            }
        
            public static String postJson(String url, String json) {
                Response response = null;
                OkHttpClient okHttpClient = new OkHttpClient();
                RequestBody body = RequestBody.create(JSON, json);
                Request request = (new Builder()).post(body).url(url).build();
                Call call = okHttpClient.newCall(request);
        
                try {
                    System.err.println("Send!!!!");
                    response = call.execute();
                    System.err.println("code = " + response.code());
                    System.err.println("all = " + response.toString());
                    return response.body().string();
                } catch (Exception var8) {
                    System.err.println("Error!!!!");
                    var8.printStackTrace();
                    return null;
                }
            }
        
            public static String post(String url, Map<String, String> params) {
                Response response = null;
                OkHttpClient okHttpClient = new OkHttpClient();
                if (params == null) {
                    params = new HashMap();
                }
        
                okhttp3.FormBody.Builder builder = new okhttp3.FormBody.Builder();
                Set<Entry<String, String>> entrySet = ((Map)params).entrySet();
                Iterator var6 = entrySet.iterator();
        
                while(var6.hasNext()) {
                    Entry<String, String> entry = (Entry)var6.next();
                    builder.add((String)entry.getKey(), (String)entry.getValue());
                }
        
                RequestBody requestBodyPost = builder.build();
                Request request = (new Builder()).post(requestBodyPost).url(url).build();
                Call call = okHttpClient.newCall(request);
        
                try {
                    System.err.println("Send!!!!");
                    response = call.execute();
                    System.err.println("code = " + response.code());
                    System.err.println("all = " + response.toString());
                    return response.body().string();
                } catch (Exception var10) {
                    System.err.println("Error!!!!");
                    var10.printStackTrace();
                    return null;
                }
            }
        
            public static String get(String url, Map<String, String> params) {
                return post(url, params);
            }
        }

[0SFH4dX.png]: https://i.imgur.com/0SFH4dX.png