Spring Boot 异常处理



  • 异常处理

    处理API中的异常和错误并向客户端发送正确的响应对于企业应用程序来说非常有用。在本章中,我们将学习如何在Spring Boot中处理异常。在进行异常处理之前,让我们了解以下注解。
  • @ControllerAdvice

    @ControllerAdvice注解用于全局处理异常。
  • @ExceptionHandler

    @ExceptionHandler注解是用于处理特定异常并将自定义响应发送到客户端的注解。
    您可以使用以下代码创建@ControllerAdvice类以全局处理异常-
    
    package com.jc2182.demo.exception;
    
    import org.springframework.web.bind.annotation.ControllerAdvice;
    
    @ControllerAdvice
    public class ProductExceptionController {
    }
    
    
    定义一个继承RuntimeException类的类。
    
    package com.jc2182.demo.exception;
    
    public class ProductNotfoundException extends RuntimeException {
       private static final long serialVersionUID = 1L;
    }
    
    
    您可以定义@ExceptionHandler方法来处理异常。此方法应用于编写Controller Advice类文件。
    
    @ExceptionHandler(value = ProductNotfoundException.class)
    
    public ResponseEntity<Object> exception(ProductNotfoundException exception) {
    }
    
    
    现在,使用下面给出的代码从API引发异常。
    
    @RequestMapping(value = "/products/{id}", method = RequestMethod.PUT)
    public ResponseEntity<Object> updateProduct() { 
       throw new ProductNotfoundException();
    }
    
    
    下面给出了处理异常的完整代码。在此示例中,我们使用了PUT API来更新产品。在这里,在更新产品时,如果找不到产品,则返回响应错误消息为“Product not found”。请注意,ProductNotFoundException异常类应继承RuntimeException。
    
    package com.jc2182.demo.exception;
    
    public class ProductNotfoundException extends RuntimeException {
       private static final long serialVersionUID = 1L;
    }
    
    
    下面给出了用于全局处理异常的Controller Advice类。我们可以在此类文件中定义任何异常处理程序方法。
    
    package com.jc2182.demo.exception;
    
    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.ControllerAdvice;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    
    @ControllerAdvice
    public class ProductExceptionController {
       @ExceptionHandler(value = ProductNotfoundException.class)
       public ResponseEntity<Object> exception(ProductNotfoundException exception) {
          return new ResponseEntity<>("Product not found", HttpStatus.NOT_FOUND);
       }
    }
    
    
    下面提供了产品服务API控制器文件以更新产品。如果未找到产品,则它将引发ProductNotFoundException类。
    现在,使用下面给出的代码从API引发异常。
    
    package com.jc2182.demo.controller;
    
    import java.util.HashMap;
    import java.util.Map;
    
    import org.springframework.http.HttpStatus;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.jc2182.demo.exception.ProductNotfoundException;
    import com.jc2182.demo.model.Product;
    
    @RestController
    public class ProductServiceController {
       private static Map<String, Product> productRepo = new HashMap<>();
       static {
          Product honey = new Product();
          honey.setId("1");
          honey.setName("Honey");
          productRepo.put(honey.getId(), honey);
          
          Product almond = new Product();
          almond.setId("2");
          almond.setName("Almond");
          productRepo.put(almond.getId(), almond);
       }
       
       @RequestMapping(value = "/products/{id}", method = RequestMethod.PUT)
       public ResponseEntity<Object> updateProduct(@PathVariable("id") String id, @RequestBody Product product) { 
          if(!productRepo.containsKey(id))throw new ProductNotfoundException();
          productRepo.remove(id);
          product.setId(id);
          productRepo.put(id, product);
          return new ResponseEntity<>("Product is updated successfully", HttpStatus.OK);
       }
    }
    
    
    下面给出了主要的Spring Boot应用程序类文件的代码
    
    package com.jc2182.demo;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    public class DemoApplication {
       public static void main(String[] args) {
          SpringApplication.run(DemoApplication.class, args);
       }
    }
    
    
    产品的POJO类的代码如下
    
    package com.jc2182.demo.model;
    public class Product {
       private String id;
       private String name;
    
       public String getId() {
          return id;
       }
       public void setId(String id) {
          this.id = id;
       }
       public String getName() {
          return name;
       }
       public void setName(String name) {
          this.name = name;
       }
    }
    
    
    Maven构建的代码– pom.xml如下所示-
    
    <?xml version="1.0" encoding="UTF-8"?>
    <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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.3.0.BUILD-SNAPSHOT</version>
            <relativePath/> <!-- lookup parent from repository -->
        </parent>
        <groupId>com.jc2182</groupId>
        <artifactId>demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>demo</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
                <exclusions>
                    <exclusion>
                        <groupId>org.junit.vintage</groupId>
                        <artifactId>junit-vintage-engine</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
        <repositories>
            <repository>
                <id>spring-milestones</id>
                <name>Spring Milestones</name>
                <url>https://repo.spring.io/milestone</url>
            </repository>
            <repository>
                <id>spring-snapshots</id>
                <name>Spring Snapshots</name>
                <url>https://repo.spring.io/snapshot</url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
            </repository>
        </repositories>
        <pluginRepositories>
            <pluginRepository>
                <id>spring-milestones</id>
                <name>Spring Milestones</name>
                <url>https://repo.spring.io/milestone</url>
            </pluginRepository>
            <pluginRepository>
                <id>spring-snapshots</id>
                <name>Spring Snapshots</name>
                <url>https://repo.spring.io/snapshot</url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
            </pluginRepository>
        </pluginRepositories>
    
    </project>
    
    
    下面给出了Gradle Build – build.gradle的代码-
    
    plugins {
        id 'org.springframework.boot' version '2.3.0.BUILD-SNAPSHOT'
        id 'io.spring.dependency-management' version '1.0.9.RELEASE'
        id 'java'
    }
    
    group = 'com.jc2182'
    version = '0.0.1-SNAPSHOT'
    sourceCompatibility = '1.8'
    
    repositories {
        mavenCentral()
        maven { url 'https://repo.spring.io/milestone' }
        maven { url 'https://repo.spring.io/snapshot' }
    }
    
    dependencies {
        implementation 'org.springframework.boot:spring-boot-starter-web'
        testImplementation('org.springframework.boot:spring-boot-starter-test') {
            exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
        }
    }
    
    test {
        useJUnitPlatform()
    }    
    
    
    RESTFul Web 服务参考上一节
    您可以创建一个可执行的JAR文件,并使用Maven或Gradle命令运行Spring Boot应用程序-
    对于Maven,您可以使用以下命令-
    
    mvn clean install
    
    
    在“BUILD SUCCESS”之后,您可以在target目录下找到JAR文件。
    对于Gradle,您可以使用以下命令-
    
    gradle clean build
    
    
    在“BUILD SUCCESSFUL”之后,您可以在build/libs目录下找到JAR文件。
    您可以使用以下命令运行JAR文件-
    
    java –jar <JARFILE>
    
    
    在Tomcat端口8080上启动应用程序
    现在在POSTMAN应用程序中请求URL,您可以看到如下所示的输出-
    PUT URL:http://localhost:8080/products/3
    springboot excpt