06.SpringBoot核心技术

目录

一、配置文件

SpringBoot除了可以在全局编写一个properties配置文件外，还可以使用yaml作为配置文件

新建一个类

@ConfigurationProperties(prefix = "person")
@Component
@Data
public class Person {
    private String userName;
    private Boolean boss;
    private Date birth;
    private Integer age;
    private String[] interests;
    private List<String> animal;
    private Map<String, Object> score;
    private Set<Double> salarys;
}

编写yaml配置文件

person:
  username: ss
  boss: true
  Date: 2019/7/8
  age: 20
  interests: [ylc,ww]
  animal:
    - 篮球
    - 足球
    - 羽毛球
  score: {English: 99,math: 66,chinese: 100}
  salarys:
    - 99.9
    - 12.3
    - 45.0

发起请求

@Autowired
Person person;

@RequestMapping("/GetPerson")
public  Person getPerson()
{
    return  person;
}

image-20210729230352223

单引号会将/n作为字符串输出，双引号会将字符串作为换行输出，双引号会转义

properties配置文件优先级大于yaml

让自定义的类和配置文件绑定一般有提示可以引入下包，可以更方便的开发

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

二、Web开发

先新建一个自动配置的SpringBoot项目

image-20210731121306112

image-20210731121357890

image-20210731121714750

静态资源访问

只要静态资源放在类路径(main)下： /static(or/publicor/resourcesor/META-INF/resources`

访问 ： 当前项目根路径/ + 静态资源名

image-20210731125415239

原理：当有控制器的情况下，请求会先找Controller处理，没有找到就找静态资源处理器，如果静态资源也找不到返回404

一般项目相会指定静态资源访问路径前缀：

application.yaml

spring:
  mvc:
    static-path-pattern: /res/**

image-20210731125517908

还可以指定静态资源的目录：

  web:
    resources:
      static-locations: [classpath:/Picture/]

image-20210731125657134

欢迎页支持

在静态资源路径下 index.html，如果配置静态资源能访问前缀就会导致index.html页面不能被访问

自定义 Favicon

欢迎页图标：默认在static下引入favicon.ico图标就可以实现

image-20210731132531279

普通参数和基本注解

1.1 @PathVariable

用于接收RestFul风格的参数，路径变量

@RestController
public class HelloController {
    //restFul风格
    @GetMapping("/hello/{name}")
    public Map<String,String>  Hello(@PathVariable("name") String name)
    {
        Map<String,String> map = new HashMap<>();
        map.put("name",name);
        return  map;
    }
 }

image-20210731140858846

还可以用一个Map集合全部接收出来

@GetMapping("/hello/{name}/age/{age}")
public Map<String,Object>  Hello2(@PathVariable Map<String,String> pv)
{
    Map<String,Object> map = new HashMap<>();
    map.put("pv",pv);
    return  map;
}

image-20210731141507949

image-20210731141936710

1.2 @RequestHeader

用于获取指定请求头

@GetMapping("/hello/{name}")
public Map<String,String>  Hello3(@PathVariable("name") String name,@RequestHeader("User-Agent") String length )
{
    Map<String,String> map = new HashMap<>();
    map.put("name",name);
    map.put("User-Agent",length);
    return  map;
}

获取全部请求头，把头部参数用一个Map接收

@GetMapping("/hello/{name}")
public Map<String,Object>   Hello3(@PathVariable("name") String name,@RequestHeader Map<String,String> pv )
{
    Map<String,Object> map = new HashMap<>();
    map.put("pv",pv);
    return  map;
}

image-20210731142146190

1.3 @RequestParam

获取指定请求参数

@GetMapping("/hello")
public Map<String,Object>   Hello3(@RequestParam("name") String name,@RequestParam("age") Integer age )
{
    Map<String,Object> map = new HashMap<>();
    map.put("name",name);
    map.put("age",age);
    return  map;
}

image-20210731151014044

获取全部参数

@GetMapping("/hello2")
public Map<String,Object>   Hello4(@RequestParam Map<String,String> params )
{
    Map<String,Object> map = new HashMap<>();
    map.put("params",params);
    return  map;
}

image-20210731151226201

1.4 @CookieValue

获取指定的Cookie值

@GetMapping("/GetCookie")
public Map<String,Object>   Hello5(@CookieValue("_ga") String _ga )
{
    Map<String,Object> map = new HashMap<>();
    map.put("_ga",_ga);
    return  map;
}

获取Cookie

@GetMapping("/GetCookie")
public Map<String,Object>   Hello5(@CookieValue("_ga") Cookie cookie )
{
    Map<String,Object> map = new HashMap<>();
    map.put("cookie",cookie);
    System.out.println(cookie.getName());
    System.out.println(cookie.getValue());
    return  map;
}
1.5 @RequestBody

获取请求体，只有Post请求才有请求体，表单提交

<form action="/save" method="post">
    用户名：<input name="username"/>
    密码：<input name="pwd"/>
    <input type="submit" value="提交">
</form>

 @PostMapping("/save")
public  Map<String,Object> PostMethod(@RequestBody String content)
 {
     Map<String,Object> map = new HashMap<>();
     map.put("content",content);
     return  map;
 }

image-20210731153234773

1.6 @RequestAttribute

获取request的属性

@Controller
public class TextController {

    @GetMapping("/goto")
    public  String goToPage(HttpServletRequest request)
    {
        request.setAttribute("msg","成功");
        return "forward:/success";
    }

    @ResponseBody
    @GetMapping("/success")
    public Map<String,Object> Success(HttpServletRequest request)
    {
        Object msg = request.getAttribute("msg");
        Map<String,Object> map = new HashMap<>();
        map.put("msg",msg);
        return map;
    }
}

image-20210731160647789

发送请求响应成功，利用转发把信息发送到成功页面

视图解析和模板引擎

Web原生组件注入

1.1 使用Selvlet API

Servlet

在主方法指定Servlet放置的位置

//servlet扫描的位置
@ServletComponentScan(basePackages = "com.ylc")
@SpringBootApplication
public class SpringBootWebApplication {

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

编写Servlet

@WebServlet(urlPatterns = "/My")
public class MyServlet  extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      resp.getWriter().write("6666");
    }
}

image-20210801145951174

Filter
@Slf4j
@WebFilter(urlPatterns = {"/public/*"})
public class MyFilter implements Filter {
    //filter初始化
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
      log.info("Filter初始化");
    }

    @Override
    public void destroy() {
        log.info("Filter销毁");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("Filter过滤");
        filterChain.doFilter(servletRequest,servletResponse);
    }
}

访问public下的都会被拦截

image-20210801151115310

image-20210801151034257

Listener
@Slf4j
@WebListener
public class MyListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
      log.info("MyListener监听到项目初始化");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        log.info("MyListener监听到项目完成");
    }
}

image-20210801151615454

1.2 RegistrationBean Springboot中注入组件

ServletRegistrationBean、FilterRegistrationBean、 ServletListenerRegistrationBean

//保证组件始终是单实例
@Configuration(proxyBeanMethods = true)
public class MyRegistConfig {

    @Bean
    public ServletRegistrationBean myServlet()
    {
        MyServlet myServlet=new MyServlet();
        return  new ServletRegistrationBean(myServlet,"/My");
    }

    @Bean
    public FilterRegistrationBean myFilter()
    {
        MyFilter myFilter=new MyFilter();
        //第一种
        //这里只有通过myServlet的请求下才会显示666 才会被过滤器找到
        //return  new FilterRegistrationBean(myFilter,myServlet());
        //第二种 自己定义过滤url
        FilterRegistrationBean filterRegistrationBean=new FilterRegistrationBean(myFilter);
        filterRegistrationBean.setUrlPatterns(Arrays.asList("/public/*"));
        return  filterRegistrationBean;
    }

    @Bean
    public ServletListenerRegistrationBean myLister()
    {
        MyListener  myListener=new MyListener();
       return new ServletListenerRegistrationBean(myListener);
    }
}

此方法同理

定制化

Web应用 编写一个配置类实现WebMvcConfigurer 即可定制化web功能，里面加@Bean给容器中再扩展一些组件

@EnableWebMvc + 实现WebMvcConfigurer接口 —— @Bean 可以全面接管SpringMVC，所有规则全部自己重新配置； 实现定制和扩展功能

三、数据访问

数据源配置

导入JDBC场景

   <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>

场景里面已经导入了数据源、JDBC、事务，还需要导入数据库的驱动，因为官方不知道我们接下要操作什么数据库

默认版本：<mysql.version>8.0.22</mysql.version>

 数据库版本要和驱动版本对应
 <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
             <version>8.0.22</version>
        </dependency>
//重新声明版本（maven的属性的就近优先原则）
    <properties>
        <java.version>1.8</java.version>
        <mysql.version>5.1.49</mysql.version>
    </properties>

分析自动配置

  • DataSourceAutoConfiguration ： 数据源的自动配置

  • 修改数据源相关的配置：spring.datasource

  • 数据库连接池的配置，是自己容器中没有DataSource才自动配置的

  • 底层配置好的连接池是：HikariDataSource

	@Configuration(proxyBeanMethods = false)
	@Conditional(PooledDataSourceCondition.class)
	@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
	@Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
			DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class,
			DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class })
	protected static class PooledDataSourceConfiguration

  • DataSourceTransactionManagerAutoConfiguration： 事务管理器的自动配置

  • JdbcTemplateAutoConfiguration： JdbcTemplate的自动配置，可以来对数据库进行crud

  • JndiDataSourceAutoConfiguration： jndi的自动配置

  • XADataSourceAutoConfiguration： 分布式事务相关的

修改配置

spring:
  datasource:
    url: jdbc:mysql://waiwanga.mysql.rds.aliyuncs.com:3306/student
    username: root
    password: XXXX
    driver-class-name: com.mysql.jdbc.Driver

@SpringBootTest
@Slf4j
class SpringBootWebApplicationTests {

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Test
    void contextLoads() {
        Long aLong = jdbcTemplate.queryForObject("select count(*) from student", Long.class);
        log.info("记录总数：{}",aLong);
    }
}

image-20210801175709977

使用Druid数据源

官方文档：https://github.com/alibaba/druid

引入jar包

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.17</version>
</dependency>

编写一个数据源配置类和配置文件关联起来

@Configuration
public class MyDataSourseConfig {

    //把DruidDataSource属性跟配置文件绑定起来
    @ConfigurationProperties("spring.datasource")
    @Bean
    public DataSource dataSource()
    {
        return new DruidDataSource();
    }
}

配置文件

spring:
  datasource:
    url: jdbc:mysql://waiwanga.mysql.rds.aliyuncs.com:3306/student
    username: root
    password: xxxx
    driver-class-name: com.mysql.cj.jdbc.Driver

测试类

@SpringBootTest
@Slf4j
class SpringBootWebApplicationTests {
    @Autowired
    JdbcTemplate jdbcTemplate;
    @Autowired
    DataSource dataSource;

    @Test
    void contextLoads() {
        Long aLong = jdbcTemplate.queryForObject("select count(*) from student", Long.class);
        log.info("记录总数：{}",aLong);
        log.info("数据源"+dataSource.getClass());
    }
}
查看监控页

访问http://localhost:8080/druid/

@Configuration
public class MyDataSourseConfig {

    //把DruidDataSource属性跟配置文件绑定起来
    @ConfigurationProperties("spring.datasource")
    @Bean
    public DataSource dataSource()
    {
        return new DruidDataSource();
    }

    //配置监控功能
    @Bean
    public ServletRegistrationBean servletRegistrationBean()
    {
        StatViewServlet statViewServlet=new StatViewServlet();
        ServletRegistrationBean<StatViewServlet> registrationBean=new ServletRegistrationBean<>(statViewServlet,"/druid/*");
        return  registrationBean;
    }
}

image-20210801193026688

开启监控功能

需要在DataSourse中Filter参数配置stat

@ConfigurationProperties("spring.datasource")
@Bean
public DataSource dataSource() throws SQLException {
    DruidDataSource dataSource=new DruidDataSource();
    //加入监控功能
    dataSource.setFilters("stat");
    return dataSource;
}

执行sql

@Autowired
JdbcTemplate jdbcTemplate;

@ResponseBody
@GetMapping("/sql")
public  String getSql()
{
    Long aLong = jdbcTemplate.queryForObject("select count(*) from student", Long.class);
    return  aLong.toString();
}

查看监控信息

image-20210801194254256

开启URl监控

WebStatFilter用于采集web-jdbc关联监控的数据

exclusions配置经常需要排除一些不必要的url，比如.js,/jslib/等等。配置在init-param中。比如：

 	<init-param>
  		<param-name>exclusions</param-name>
  		<param-value>*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*</param-value>
  	</init-param>

根据官方xml，写成注解的方式

@Bean
public FilterRegistrationBean webstatFilter()
{
    WebStatFilter webStatFilter=new WebStatFilter();
    FilterRegistrationBean<WebStatFilter> filterRegistrationBean=new FilterRegistrationBean<>(webStatFilter);
    filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
    filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
return  filterRegistrationBean;
}

可以查看每次请求的信息

image-20210801202925930

开启防火墙

使用缺省配置的WallFilter

  <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
      ...
      <property name="filters" value="wall"/>
  </bean>

根据官方文档，只需要在之前的filters中再添加一个参数wall

image-20210801203613399

image-20210801203550529

开启Session监控

需要配置Servlet的 loginUsername 和 loginPassword这两个初始参数

image-20210801204331970

再次刷新进入

image-20210801204414303

登陆上就可以看到Session信息

image-20210801204729756

引入官方starter方式

引入druid-starter

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.17</version>
</dependency>

分析自动配置

  • 扩展配置项 spring.datasource.druid

  • DruidSpringAopConfiguration.class, 监控SpringBean的；配置项：spring.datasource.druid.aop-patterns

  • DruidStatViewServletConfiguration.class, 监控页的配置：spring.datasource.druid.stat-view-servlet；默认开启

  • DruidWebStatFilterConfiguration.class, web监控配置；spring.datasource.druid.web-stat-filter；默认开启

  • DruidFilterConfiguration.class}) 所有Druid自己filter的配置

#spring:
#  mvc:
#    static-path-pattern: /res/**
#  web:
#    resources:
#      static-locations: [classpath:/Picture/]
spring:
  datasource:
    url: jdbc:mysql://waiwanga.mysql.rds.aliyuncs.com:3306/student
    username: root
    password: xxxxx
    driver-class-name: com.mysql.cj.jdbc.Driver


    druid:
      aop-patterns: com.ylc.* #监控SpringBean
      filters: stat,wall  # 底层开启功能，stat（sql监控），wall（防火墙）

      stat-view-servlet: # 配置监控页功能
        enabled: true
        login-password: 123
        login-username: admin
        reset-enable: true

      web-stat-filter:  # 监控web
        enabled: true
        urlPattern: /*
        exclusions: '*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*'

      filter:
        stat:    # 对上面filters里面的stat的详细配置
         slow-sql-millis: 1000
         logSlowSql: true
        enabled: true
        wall:
         enabled: true
         config:
         drop-table-allow: false

image-20210801215351628

SpringBoot配置示例

https://github.com/alibaba/druid/tree/master/druid-spring-boot-starter

配置项列表

https://github.com/alibaba/druid/wiki/DruidDataSource%E9%85%8D%E7%BD%AE%E5%B1%9E%E6%80%A7%E5%88%97%E8%A1%A8

整合Mybatis操作

官方文档：https://github.com/mybatis

引入jar包

  <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>
    <dependency>  
            <groupId>mysql</groupId>  
            <artifactId>mysql-connector-java</artifactId>  
    </dependency>  
 <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

编写全局配置文件

spring:
  datasource:
    url: jdbc:mysql://waiwanga.mysql.rds.aliyuncs.com:3306/student
    username: xxx
    password: XXX
    driver-class-name: com.mysql.cj.jdbc.Driver


mybatis:
  #config-location: classpath:Mybatis/mybatis-config.xml
  mapper-locations: classpath:mapper/*.xml
  configuration:  #指定Mybatis全局配置文件中的配置项  有了这个就不需要mybatis-config.xml
    map-underscore-to-camel-case: true

编写实体类

@Data
public class Student {
    public  String name;
    public int id;
    public int getId;
}

编写Mapper接口

@Mapper
public interface StudentMapper {
    //获取所有学生
    List<Student> getStudent();
}

在resourse文件夹下编写mapper文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ylc.springbootweb.mapper.StudentMapper">

    <select id="getStudent" resultType="com.ylc.springbootweb.bean.Student">
        select * from student
    </select>
</mapper>

编写StudentService

@Service
public class StudentService {

    @Autowired
    StudentMapper studentMapper;

    public List<Student> getStudent()
    {
        return studentMapper.getStudent();
    }
}

编写控制器

@Controller
@ResponseBody
public class StudentController {

    @Autowired
    StudentService studentService;

    @GetMapping("/getStu")
    public List<Student> getStudent()
    {
        List<Student> students=studentService.getStudent();
        for (Student student : students) {
            System.out.println(student);
        }
        return  students;
    }
}

image-20210803211110362

注意mapper.xml文件和Mybatis配置文件不能放在同一层级，不然系统识别不了哪个是配置文件

整合Mybatis-Plus

引入Mybatis-Plus jar包

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>

在SpringBootWebApplication中用@MapperScan扫描Mapper接口

继承BaseMapper实现crud

public interface PlusStudentMapper<T> extends BaseMapper<Student> {

}

测试

@Autowired
PlusStudentMapper plusStudentMapper;
@Test
void  plusText()
{
    Student student = (Student) plusStudentMapper.selectById(2);
    System.out.println(student);
}

image-20210803224941023

Crud操作

编写Mapper接口

public interface StudentMapper<T> extends BaseMapper<Student> {

}

编写service接口

public interface TService extends IService<Student> {

}

编写service实现类

@Service
public class StudentTServiceImp extends ServiceImpl<StudentMapper<Student>,Student> implements TService {

}

测试类

@Autowired
StudentTServiceImp serviceImp;
@Test
void  Crud()
{
    List<Student> list = serviceImp.list();
    for (Student student : list) {
        System.out.println(student);
    }
}

image-20210803234544458

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原文地址：https://www.cnblogs.com/cg-ww/p/15126721.html