Spring Boot整合JSP出现No mapping for GET请求错误的解决求助

问题描述 #

开发Spring Boot Web应用时出现“No mapping for GET”错误，错误界面如下：

相关代码与配置 #

EmployeeController代码 #

package com.examenjsp.jsp.controllers;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

import com.examenjsp.jsp.jdbcConnect;


@Controller
@EnableWebMvc
@RequestMapping("/views") // Applies to all routes within this controller
public class EmployeeController {


    @GetMapping({"/", "/index"})
    public String showIndex(Model model) {
        String query = "SELECT * FROM employees";
        String url = "jdbc:mysql://localhost:3306/employeesdb";
        String name = "root";
        String password = "rootadmin223";
        String table = jdbcConnect.GetTable(query, url, name, password);
        model.addAttribute("employeeTable", table);
        return "index"; // 
    }


    @PostMapping("/action_page")
    public String addEmployee(
            @RequestParam("first_name") String firstName,
            @RequestParam("last_name") String lastName,
            @RequestParam("salary_pm") float salaryPm,
            @RequestParam("hire_date") String hireDate,
            @RequestParam("company") String company,
            @RequestParam("department") String department) {

        jdbcConnect.addValue(firstName, lastName, salaryPm, hireDate, company, department);
        return "redirect:/views/index"; // Redirects back to index after adding
    }


    @PostMapping("/edit_employee")
    public String editEmployee(@RequestParam("employee_id") int employeeId, Model model) {
        try {
            ResultSet rs = jdbcConnect.getValue(employeeId);
            if (rs != null && rs.next()) {
                model.addAttribute("employeeId", employeeId);
                model.addAttribute("firstName", rs.getString("first_name"));
                model.addAttribute("lastName", rs.getString("last_name"));
                model.addAttribute("salaryPm", rs.getFloat("salary_pm"));
                model.addAttribute("hireDate", rs.getString("hire_date"));
                model.addAttribute("company", rs.getString("company"));
                model.addAttribute("department", rs.getString("department"));
                return "edit_employee"; // Shows edit_employee.jsp
            } else {
                model.addAttribute("error", "Employee not found");
                return "error"; // Shows an error page if employee isn't found
            }
        } catch (SQLException e) {
            e.printStackTrace();
            model.addAttribute("error", "Error occurred while fetching employee details: " + e.getMessage());
            return "error"; // Shows an error page on SQL exceptions
        }
    }

    // PostMapping to update an employee's details
    @PostMapping("/update_employee")
    public String updateEmployee(
            @RequestParam("employee_id") int employeeId,
            @RequestParam("first_name") String firstName,
            @RequestParam("last_name") String lastName,
            @RequestParam("salary_pm") float salaryPm,
            @RequestParam("hire_date") String hireDate,
            @RequestParam("company") String company,
            @RequestParam("department") String department) {

        jdbcConnect.setValue(employeeId, firstName, lastName, salaryPm, hireDate, company, department);
        return "redirect:/views/index"; // Redirects back to index after updating
    }

    // PostMapping to delete an employee
    @PostMapping("/delete_employee")
    public String deleteEmployee(@RequestParam("employee_id") int employeeId) {
        jdbcConnect.dropValue(employeeId);
        return "redirect:/views/index"; // Redirects back to index after deleting
    }
}

ExamenJspSpringApplication代码 #

package com.examenjsp.jsp;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer;
import org.springframework.security.web.SecurityFilterChain;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@EnableWebMvc
@SpringBootApplication()
@ComponentScan(basePackages = { "com.examenjsp.jsp", "com.examenjsp.jsp.configuration","com.examenjsp.jsp.controllers"}, excludeFilters = { @Filter(type = FilterType.ANNOTATION, value = Configuration.class) })

public class ExamenJspSpringApplication extends SpringBootServletInitializer{

    public static void main(String[] args) {
        SpringApplication.run(ExamenJspSpringApplication.class, args);
    }
    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        http.authorizeRequests(authorizeRequests -> authorizeRequests.anyRequest()
          .permitAll())
          .csrf(AbstractHttpConfigurer::disable);
        return http.build();
    }
}

应用结构 #

application.properties配置 #

spring.mvc.static-path-pattern=/WEB-INF/views/
spring.mvc.view.prefix=/WEB-INF/views/
spring.mvc.view.suffix=.jsp
server.port=8082
spring.datasource.url=jdbc:mysql://localhost:3306/employeesdb
spring.datasource.username=root
spring.datasource.password=rootadmin223
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

解决方法 #

1. 修正静态资源路径配置 #

spring.mvc.static-path-pattern是用来指定CSS、JS等静态资源的访问路径，你现在把它设成了视图文件所在的目录，会导致Spring无法正确解析控制器返回的视图。修改application.properties：

# 删除或注释掉错误的静态路径配置，若需要静态资源，可设置为/static/**
# spring.mvc.static-path-pattern=/WEB-INF/views/
spring.mvc.view.prefix=/WEB-INF/views/
spring.mvc.view.suffix=.jsp

2. 移除冗余的@EnableWebMvc注解 #

@EnableWebMvc会关闭Spring Boot的自动Web配置，你在控制器和主类都加了这个注解，大概率导致视图解析器失效。直接删掉EmployeeController上的@EnableWebMvc，主类上的也建议移除，除非你有自定义MVC配置的需求。

3. 简化组件扫描配置 #

@SpringBootApplication已经默认扫描当前包及其子包，不需要额外写@ComponentScan，而且你排除了Configuration类，可能导致必要的配置无法加载。修改主类：

@SpringBootApplication
public class ExamenJspSpringApplication extends SpringBootServletInitializer{
    // 原有main方法和SecurityFilterChain Bean保留
}

4. 确认访问路径正确 #

控制器根路径是/views，showIndex方法映射了/和/index，所以正确访问路径是http://localhost:8082/views/index或http://localhost:8082/views/，不要直接访问http://localhost:8082/，这个路径没有对应的控制器映射。

5. 检查JSP文件匹配度 #

确保WEB-INF/views下的JSP文件名和控制器返回的视图名完全一致，比如返回index就对应index.jsp，注意大小写敏感。

6. 排查JDBC工具类异常 #

虽然当前是映射错误，但如果jdbcConnect中的方法抛出未捕获异常，可能导致控制器无法正常返回视图。建议在控制器方法中加强异常处理，或者确保JDBC工具类的逻辑不会阻断请求流程。

内容的提问来源于stack exchange，提问作者Balta Cristian