环境：
jdk1.8
java8
springboot2.6.13
swagger2.9.2

添加依赖

pom.xml

<!--        添加swagger2-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
<!--        添加swagger-ui-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>

config工作包中新增SwaggerConfig

SwaggerConfig

package com.example.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2 //启用swagger2功能
public class SwaggerConfig {
    /**
     * 配置swagger2相关的bean
     */
    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .select()
                .apis(RequestHandlerSelectors.basePackage("com"))
                .paths(PathSelectors.any())
                .build();
    }

    /**
     * 此处主要是API文档页面显示信息
     */
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("SpringBoot整合Swagger2")
                .description("SpringBoot整合Swagger2")
                .termsOfServiceUrl("")
                .version("1.0")
                .build();
    }
}

报错

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException

解决：

//application.properties
spring.mvc.pathmatch.matching-strategy=ant_path_matcher

注解

作用范围	API	API常用参数	作用位置
协议集描述	@Api	@Api(tags = {“tag1”,“tag2”,“…”})	controller类
协议描述	@ApiOperation	@ApiOperation(value = “功能描述”,notes = “备注”)	controller类的方法
描述返回对象的意义	@ApiModel	@ApiModel(value=“类名”,description=“类描述”)	返回对象类
对象属性	@ApiModelProperty	@ApiModelProperty(value = “类属性描述”,required = true,example = “属性举例”,notes = “备注”)	出入参数对象的字段
非对象参数集	@ApiImplicitParams	@ApiImplicitParams({@ApiImplicitParam(),@ApiImplicitParam(),…})	controller的方法
非对象参数描述	@ApiImplicitParam	@ApiImplicitParam(name = “参数名”,value = “参数描述”,required = true,paramType = “接口传参类型”,dataType = “参数数据类型”)	@ApiImplicitParams的方法里用
Response集	@ApiResponses	@ApiResponses({ @ApiResponse(),@ApiResponse(),…})	controller的方法
Response	@ApiResponse	@ApiResponse(code = 10001, message = “返回信息”)	@ApiResponses里用
忽略注解	@ApiIgnore	@ApiIgnore	类，方法，方法参数

package com.example.water.controller;

import com.example.water.entity.User;
import io.swagger.annotations.*;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@Api(tags = "控制器说明：用户控制器")
@RestController
public class UserController {

    @ApiOperation("接口说明：查询用户接口")
    @RequestMapping(value = "/getUser", method = RequestMethod.GET)
    public String getUser(@ApiParam(name = "姓名") String name) {
        return name;
    }

    @ApiOperation("接口说明：用户接口")
    @ApiImplicitParams({
            @ApiImplicitParam(name = "username", value = "用户名", dataType = "String", defaultValue = "dai"),
    })
    @RequestMapping(value = "/setUser", method = RequestMethod.GET)
    @ResponseBody
    public User user(@RequestParam(name = "name") String name) {
        User user = new User();
        user.setName(name);
        return user;
    }
}

package com.example.water.entity;

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;

@ApiModel("实体类说明：用户实体类")
public class User {

    @ApiModelProperty("姓名")
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

swagger
http://localhost:8080/swagger-ui.html

Knife4j
http://127.0.0.1:8080/doc.htm
配置与swagger一样，只需要再加个依赖

<dependency>
            <groupId>com.github.xiaoymin</groupId>
            <artifactId>knife4j-openapi2-spring-boot-starter</artifactId>
            <version>4.4.0</version>
</dependency>