折腾：
【未解决】VSCode中搭建Spring Boot的示例程序
期间，虽然
mvn spring-boot:run
可以继续运行了，但是最后出错了：
2020-01-18 20:48:06.237 WARN 19665 --- [ restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'greeting': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'long' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
2020-01-18 20:48:06.240 INFO 19665 --- [ restartedMain] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2020-01-18 20:48:06.256 INFO 19665 --- [ restartedMain] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-01-18 20:48:06.430 ERROR 19665 --- [ restartedMain] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
Parameter 0 of constructor in com.crifan.xxx.Greeting required a bean of type 'long' that could not be found.
Action:
Consider defining a bean of type 'long' in your configuration.
Parameter 0 of constructor in Greeting required a bean of type long that could not be found
去看看此处的
com.crifan.xxx.Greeting
没太看懂，需要怎么改
尝试加：
@Configuration
@ConfigurationProperties("id")结果会报错：
Configuration cannot be resolved to a type Java(16777218)
去快速修复
然后去导入
import org.springframework.context.annotation.Configuration;
即可。
同理，对于：
ConfigurationProperties cannot be resolved to a typeJava(16777218)
去导入
import org.springframework.boot.context.properties.ConfigurationProperties;
是不是这样就意味着：
可以自动给id这个属性，去Configuration配置了？
再去运行
mvn spring-boot:run
看看是否能解决问题。
结果错误有其他变化了：
✗ mvn spring-boot:run [INFO] Scanning for projects... 。。。 [INFO] [INFO] --- spring-boot-maven-plugin:2.2.2.RELEASE:run (default-cli) @ xxx --- [INFO] Attaching agents: [] Exception in thread "main" java.lang.Error: Unresolved compilation problem: at com.crifan.xxx.Greeting.main(Greeting.java:11) [INFO] ------------------------------------------------------------------------ [INFO] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Total time: 4.122 s [INFO] Finished at: 2020-01-18T21:13:33+08:00 [INFO] ------------------------------------------------------------------------ [ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.2.RELEASE:run (default-cli) on project xxx: Application finished with exit code: 1 -> [Help 1] [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
现在从错误
Parameter 0 of constructor in com.crifan.xxx.Greeting required a bean of type 'long' that could not be found.
对应的代码中
public Greeting(long id, String content) {
this.id = id;
this.content = content;
}可以看出大概意思：
Greeting的构造函数中，第一个参数是long的，但是此处缺少了
所以问题变成：
搞清楚，此处运行
mvn spring-boot:run
内部运行的机制，为何没有传递参数给Greeting
然后去试试：
【未解决】spring boot尝试添加@ConstructorBinding以解决错误Parameter 0 of constructor in required a bean of type
恢复到最基本的
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Greeting {
public static void main(String[] args) {
SpringApplication.run(Greeting.class, args);
}
private final long id;
private final String content;
public Greeting(long id, String content) {
this.id = id;
this.content = content;
}
public long getId() {
return id;
}
public String getContent() {
return content;
}
}结果又是最开始的错误
*************************** APPLICATION FAILED TO START *************************** Description: Parameter 0 of constructor in com.crifan.xxx.Greeting required a bean of type 'long' that could not be found. Action: Consider defining a bean of type 'long' in your configuration.
【总结】
此处之前是参考了多个教程：
然后给代码：
src/server/xxx/xxx/src/main/java/com/crifan/xxx/Greeting.java
public class Greeting {加上了：
@SpringBootApplication
public class Greeting {然后之后就是此处错误
Parameter 0 of constructor in com.crifan.xxx.Greeting required a bean of type 'long' that could not be found.
了，而后续有试了多种其他annotation：
- @ConstructorBinding
- @EnableConfigurationProperties
- @ConfigurationPropertiesScan
- @ConfigurationProperties(“id”)
导致更多其他错误。
最后是参考
才搞懂：
此处Greeting中，是不应该加上@SpringBootApplication的
应该是普通的纯的class，即：
src/server/xxx/xxx/src/main/java/com/crifan/xxx/Greeting.java
去掉额外的annotation，只保留普通的类的变量：
package com.crifan.xxx;
// import org.springframework.boot.SpringApplication;
// import org.springframework.boot.autoconfigure.SpringBootApplication;
// import org.springframework.boot.context.properties.ConfigurationProperties;
// import org.springframework.boot.context.properties.ConfigurationPropertiesScan;
// import org.springframework.boot.context.properties.ConstructorBinding;
// import org.springframework.boot.context.properties.EnableConfigurationProperties;
// import org.springframework.context.annotation.Configuration;
// @EnableConfigurationProperties(Greeting::class)
// @Configuration
// @ConfigurationProperties("id")
// @SpringBootApplication
// @ConstructorBinding
// @ConfigurationPropertiesScan
public class Greeting {
// public static void main(String[] args) {
// SpringApplication.run(Greeting.class, args);
// }
private final long id;
private final String content;
public Greeting(long id, String content) {
this.id = id;
this.content = content;
}
public long getId() {
return id;
}
public String getContent() {
return content;
}
}
同时，之前已有GreetingController：
src/server/xxx/xxx/src/main/java/com/crifan/xxx/GreetingController.java
package com.crifan.xxx;
import java.util.concurrent.atomic.AtomicLong;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
@RestController
public class GreetingController {
private static final String template = "Hello, %s!";
private final AtomicLong counter = new AtomicLong();
@GetMapping("/greeting")
public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
return new Greeting(counter.incrementAndGet(), String.format(template, name));
}
}然后再去加上：
src/server/xxx/xxx/src/main/java/com/crifan/xxx/ServingWebContentApplication.java
package com.crifan.xxx;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class ServingWebContentApplication {
public static void main(String[] args) {
SpringApplication.run(ServingWebContentApplication.class, args);
}
}用于启动服务的SpringBootApplication的SpringApplication.run
即可正常运行
mvn spring-boot:run
消除当前错误了。
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