实现一个自定义的spring boot starter

spring boot大家都知道，是集成了spring的几乎所有类库，通过它核心的spring-boot-autoconfigure模块，结合一系列的starter来完成原本需要开发人员配置的各种xml和依赖jar的工作，开发人员针对自身需求，只要引入指定的starter即可。

下面就来实现一个自定义的spring boot starter。主要功能是拦截所有controller请求，并打印出请求参数和header部信息。

看了网上很多人都拆分成两个模块，autoconfigure模块和starter模块，我这里给的例子是只包含starter模块。

首先建一个maven项目
在resources目录下新建META-INF目录，并在此目录下新建spring.factories文件，内容如下：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.huang.AutoInitConfigurer,\
com.huang.CustomWebConfigurer

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\是固定的, 另外的是看需求，我这里定义了两个@Configuration

AutoInitConfigurer.java

@Configuration
public class AutoInitConfigurer {

    @Bean
    @ConditionalOnMissingBean
    public LogInterceptor1 logInterceptor1() {
        return new LogInterceptor1();
    }

}

CustomWebConfigurer.java

@Configuration
public class CustomWebConfigurer extends WebMvcConfigurerAdapter {

    private final LogInterceptor1 logInterceptor1;

    @Autowired
    public CustomWebConfigurer(LogInterceptor1 logInterceptor1) {
        this.logInterceptor1 = logInterceptor1;
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(logInterceptor1);
        super.addInterceptors(registry);
    }
}

定义拦截器，拦截所有controller的请求

@Slf4j
public class LogInterceptor1 extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        String requestParams = getQueryString(request.getParameterMap());
        String headers = getHeaderStr(request);

        log.info("request params = {} header = {}", requestParams, headers);

        return true;
    }

    public static String getHeaderStr(HttpServletRequest request) {
        try {
            StringBuilder sb = new StringBuilder(256);
            Enumeration e = request.getHeaderNames();

            while(e.hasMoreElements()) {
                String name = (String)e.nextElement();
                Enumeration headerValues = request.getHeaders(name);

                while(headerValues.hasMoreElements()) {
                    sb.append(name).append("=").append((String)headerValues.nextElement()).append("&");
                }
            }


            return sb.toString();
        } catch (Exception e) {
            return "";
        }
    }

    public static String getQueryString(Map<String, String[]> params) {
        try {
            StringBuilder sb = new StringBuilder(256);
            if (params != null && !params.isEmpty()) {
                params.keySet().stream().forEach((key) -> sb.append(key).append("=").append(params.get(key)[0]).append("&"));
                sb.deleteCharAt(sb.length() - 1);
            }

            return sb.toString();
        } catch (Exception e) {
            return "";
        }
    }
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.huang</groupId>
  <artifactId>log-spring-boot-starter</artifactId>
  <packaging>jar</packaging>
  <version>1.0.0-SNAPSHOT</version>
  <url>http://maven.apache.org</url>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.12.RELEASE</version>
    <relativePath/>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-test</artifactId>
    </dependency>

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

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

    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
        <includes>
          <include>*.yml</include>
        </includes>
      </resource>
      <resource>
        <directory>src/main/resources</directory>
        <filtering>false</filtering>
        <includes>
          <include>*.yml</include>
        </includes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>

      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-deploy-plugin</artifactId>
        <version>2.8.2</version>
        <configuration>
          <skip>true</skip>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>8</source>
          <target>8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

最终打成jar包，上传到maven仓库。

好了，在我们的开发项目中只要依赖进来这个jar，并且定义一个WebMvcConfigurerAdapter类，并注册上面定义的LogInterceptor1 拦截器就能实现日志打印功能。

pom.xml依赖如下：

 <dependency>
    <groupId>com.huang</groupId>
    <artifactId>log-spring-boot-starter</artifactId>
    <version>1.0.0-SNAPSHOT</version>
 </dependency>

定义CustomWebAppConfigurer类

@Configuration
@Slf4j
public class CustomWebAppConfigurer extends WebMvcConfigurerAdapter {

    @Autowired
    private LogInterceptor1 logInterceptor1;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(logInterceptor1).addPathPatterns("/**");
        super.addInterceptors(registry);
    }
}