Question

我已经尝试了stackoverflow上提到的大多数建议但尚未遇到解决方案。我正在提出的错误如下。

An error occurred at line: 379 in the jsp file: /application-new-project_process.jsp
Lambda expressions are allowed only at source level 1.8 or above

我正在使用 IntelliJ IDEA 2016.2 并已应用这些设置。

Project Structure→Project，Project SDK至1.8 (java version "1.8.0_102")

Project Structure→Project，Project Language Level至8.0 - Lambdas, type annotations etc.

Settings→Build, Execution, Deployment→Compiler→Java Compiler，Project bytecode version至1.8

Settings→Build, Execution, Deployment→Compiler→Java Compiler，Target bytecode version至1.8

我正在使用 Tomcat v8.0.36 ，并为JSP servlet提供以下内容。

<servlet>
    <servlet-name>jsp</servlet-name>
    <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
    <init-param>
        <param-name>fork</param-name>
        <param-value>false</param-value>
    </init-param>
    <init-param>
        <param-name>xpoweredBy</param-name>
        <param-value>false</param-value>
    </init-param>
    <init-param> 
        <param-name>compiler</param-name> 
        <param-value>modern</param-value> 
    </init-param> 
    <init-param> 
        <param-name>compilerSourceVM</param-name> 
        <param-value>1.8</param-value> 
    </init-param> 
    <init-param> 
        <param-name>compilerTargetVM</param-name> 
        <param-value>1.8</param-value> 
    </init-param> 
    <init-param> 
        <param-name>suppressSmap</param-name> 
        <param-value>true</param-value> 
    </init-param> 
    <load-on-startup>3</load-on-startup>
</servlet>

任何建议都将不胜感激！

Answer 1

我使用IntelliJ IDEA 2016.3.2，tomcat apache-tomcat-8.5.8，以下更改对我来说已经足够了：
1.更改以下文件：apache-tomcat-8.5.8 \ conf \ web.xml
2.修改

的配置

 <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>

添加以下init参数：

＆LT; INIT-PARAM＆GT;
＆LT; PARAM-名称＆gt;＆compilerSourceVM LT; / PARAM-名称＆gt;
＆LT; PARAM值＆GT; 1.8＆LT; / PARAM值＆GT;
＆LT; / INIT-PARAM＆GT;
＆LT; INIT-PARAM＆GT;
＆LT; PARAM-名称＆gt;＆compilerTargetVM LT; / PARAM-名称＆gt;
＆LT; PARAM值＆GT; 1.8＆LT; / PARAM值＆GT;
＆LT; / INIT-PARAM＆GT;

完成。

Answer 2

使用Spring Boot 1.5.9.RELEASE和Tomcat 8.5.23的更新答案。由于Spring Boot / MVC中没有针对Tomcat的XML配置文件，因此我调整了从these spring docs链接的代码，以在我的基础Application类中创建自定义程序bean。修复了在IntelliJ和Gradle CLI中使用JSP中的Java 8语法导致的问题。

@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(MyApplication.class);
    }

    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }

    @Bean
    public EmbeddedServletContainerCustomizer containerCustomizer() {
        return (ConfigurableEmbeddedServletContainer container) -> {
            TomcatEmbeddedServletContainerFactory tomcat = (TomcatEmbeddedServletContainerFactory) container;
            JspServlet servlet = tomcat.getJspServlet();
            Map<String, String> jspServletInitParams = servlet.getInitParameters();
            jspServletInitParams.put("compilerSourceVM", "1.8");
            jspServletInitParams.put("compilerTargetVM", "1.8");
            servlet.setInitParameters(jspServletInitParams);
        };
    }

}

JSP文件中的Lambda表达式将无法编译

2 个答案: