Servlet写回响应数据工具类 ResultWriter

怼烎@ 2022-02-03 04:57 183阅读 0赞

## intro ##

这是一个工具类，封装了常用的操作：`Servlet`中写回响应数据|出错后的响应数据。  
也没有用到设计模式。依赖如下：

*  `fastjson`
 *  `servlet`

## Structure ##

![Structure][]

## Code ##

package cn.jt.util.dbutil;
    
    import com.alibaba.fastjson.JSON;
    
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.io.PrintWriter;
    
    /**
     * 将响应数据写回
     *
     * @author wyj
     * @create 2019-04-29 21:27
     */
    public class ResultWriter {
    
        /**
         * 默认的HTTP错误码
         */
        private static int defaultErrorStatusCode = 404;
    
        /**
         * 默认的响应数据的内容类型
         */
        private static String defaultContentType = "text/json";
    
        /**
         * 写回响应数据
         * @param response 响应对象，用于设置contentType和获取PrintWriter。
         * @param result 要写回的对象(在本方法内部用JSON.toJSONString()转换为jsonStr格式)
         * @param prettyFormat 是否美化json串的格式
         * @param contentType 响应的内容类型，默认为"text/json"
         * @throws IOException 可能由response.getWriter()抛出
         */
        public static void write(HttpServletResponse response, Object result, boolean prettyFormat, String contentType) throws IOException {
            response.setContentType(contentType);
            PrintWriter writer = response.getWriter();
            writer.write(JSON.toJSONString(result, prettyFormat));
            writer.close();
        }
        public static void write(HttpServletResponse response, Object result) throws IOException {
            write(response, result, true, defaultContentType);
        }
    
        /**
         * 后端操作出错时，写回响应消息
         * @param response 响应
         * @param msg 要写回的消息
         * @param status 返回的HTTP错误码
         * @param contentType 响应的内容类型
         * @throws IOException
         */
        public static void occurException(HttpServletResponse response, Object msg, int status, String contentType) throws IOException {
            response.setStatus(status);
            response.setContentType(contentType);
            PrintWriter writer = response.getWriter();
            writer.write(JSON.toJSONString(msg));   // 写回错误数据
            writer.close();
        }
        public static void occurException(HttpServletResponse response, Object msg) throws IOException {
            occurException(response, msg, defaultErrorStatusCode, defaultContentType);
        }
    
    }

[Structure]: /images/20220203/56f9f2ac6b7d483893e2f18dc3cb0f9b.png