如何使用 Spring Boot 2（Spring 5 + Tomcat 9）將 JSP 渲染捕獲到字符串中？

Question

我已經實現了 SwallowingHttpServletResponse 示例，該示例可在線上的各種示例中找到。 It has worked for me in the past when I was using Spring 4 and Tomcat 7, but now that I have migrated to using Spring Boot 2 (which uses Spring 5 and embedded Tomcat 9) capturing the JSP rendering doesn't seem to work anymore . 有人知道如何讓 SwallowingHttpServletResponse 示例與 Spring Boot 2 (Spring 5 + Tomcat 9) web 應用程序一起使用嗎？

適用於 Spring 4 + Tomcat 7 的代碼示例：

• https://technologicaloddity.com/2011/10/04/render-and-capture-the-output-of-a-jsp-as-a-string/
• https://www.javatips.net/api/CaptureJSP-master/src/main/java/com/technologicaloddity/capturejsp/util/SwallowingJspRenderer.java

Answer 1

我面臨着類似的問題。 升級到 Spring 5 和 Tomcat 8.5 后，我的內部 jsp 渲染方法停止工作。 原來我沒有在模擬請求中定義請求方法（如 GET）。 這可能是過去默認的？ 沒有花太多時間研究它...

無論如何，這是代碼：

服務：

@Service
public class JspService implements ServletContextAware {

    private InternalResourceViewResolver viewResolver;

    @Autowired
    public void setViewResolver(InternalResourceViewResolver viewResolver) {
        this.viewResolver = viewResolver;
    }

    private ServletContext context;

    @Override
    public void setServletContext(ServletContext servletContext) {
        this.context = servletContext;
    }

    public String renderJspView(String viewName, ModelMap modelMap) throws Exception {

        RequestDispatcher requestDispatcher = context.getRequestDispatcher("/WEB-INF/jsp/" + viewName + ".jsp");
        View view = viewResolver.resolveViewName(viewName, Locale.US);

        MockHttpServletResponse mockResp = new MockHttpServletResponse();
        HttpServletRequest mockRequest = new MockHttpServletRequest();
        JspRequestWrapper requestWrapper = new JspRequestWrapper(mockRequest, requestDispatcher);
        mockResp.flushBuffer(); // important! forces servlet include

        view.render(modelMap, requestWrapper, mockResp);

        return mockResp.getContentAsString();
    }
}

請求包裝器

public class JspRequestWrapper extends HttpServletRequestWrapper {

    private final RequestDispatcher requestDispatcher;

    public JspRequestWrapper(HttpServletRequest request, RequestDispatcher requestDispatcher) throws IOException {
        super(request);
        this.requestDispatcher = requestDispatcher;
    }


    @Override
    public RequestDispatcher getRequestDispatcher(String path) {
        return requestDispatcher;
    }

    // Hardcode contextPath and URI so links work
    @Override
    public String getContextPath() {
        return "https://foo.bar.com/<webapp name>";
    }

    @Override
    public String getRequestURI() {
        return "foo.bar.com";
    }

    // Define request method!
    @Override
    public String getMethod() {
        return "GET";
    }
}