java servlet printWriter.close();没有影响

Question

import jakarta.servlet.ServletException;
import jakarta.servlet.ServletInputStream;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
@Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try (
                ServletInputStream inputStream = req.getInputStream();
                InputStreamReader reader = new InputStreamReader(inputStream, "utf-8");
                BufferedReader bufferedReader = new BufferedReader(reader);
                PrintWriter printWriter = resp.getWriter()
        ) {
            String line;
            StringBuilder builder = new StringBuilder();
            while ((line = bufferedReader.readLine()) != null) {
                builder.append(line);
            }
            String json = builder.toString();
            GoodsInfo goodsInfo = JSONObject.parseObject(json, GoodsInfo.class);
            if (goodsInfo != null) {
                Result result;
                if (goodsInfo.getGoodsId() == null) {
                    result = service.insertSelective(goodsInfo);
                } else {
                    result = service.updateByPrimaryKeySelective(goodsInfo);
                }
                String toJSONString = JSONObject.toJSONString(result);
                printWriter.write(toJSONString);
                printWriter.close();
            }

        }

    }

在servlet中最后一段代码

printWriter.close();

为什么是虚的

Answer 1

一般 idea 中代码灰色显示，说明你这个代码是无用的。你可以将鼠标移到灰色显示的代码上，一般会有提示的。

你这里用了try with resource 的这种写法，是会自动关闭流的，不用手动去执行close方法。

关于try with resource 可以看下这个博客 https://blog.csdn.net/tianzhonghaoqing/article/details/118720380