Spring Boot 教程:异常处理

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【注】本文译自:[https://www.tutorialspoint.com/spring_boot/spring_boot_exception_handling.htm](https://www.tutorialspoint.com/spring_boot/spring_boot_exception_handling.htm)
![](https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/000cbc701e3742a692a588ad226dbcd7~tplv-k3u1fbpfcp-zoom-1.image)
对于企业应用而言,在 API 中处理好异常和错误是至关重要的。本文将带你学习如果在 Spring Boot 中处理异常。
在学习异常处理前让我们先来理解下面的注解:

Controller Advice

@ControllerAdvice 注解用于处理全局异常。

Exception Handler

@ExceptionHandler 注解是用于处理指定的异常并向客户端发送一个自定义的响应。
可以使用下面的代码来创建 @ControllerAdvice 类以处理全局异常:
package com.tutorialspoint.demo.exception;import org.springframework.web.bind.annotation.ControllerAdvice;@ControllerAdvice   public class ProductExceptionController {}
    定义一个继承 RuntimeException 的类。
package com.tutorialspoint.demo.exception;public class ProductNotfoundException extends RuntimeException {   private static final long serialVersionUID = 1L;}
    如下所示,可以定义 @ExceptionHandler 方法来处理异常。这个方法应当被用于编写 Controller Advice 类文件。
@ExceptionHandler(value = ProductNotfoundException.class)public ResponseEntity<Object> exception(ProductNotfoundException exception) {}
    现在,使用以下代码来抛出来自 API 的异常:
@RequestMapping(value = "/products/{id}", method = RequestMethod.PUT)public ResponseEntity<Object> updateProduct() {   throw new ProductNotfoundException();}
    完整的异常处理代码如下所示。在这个例子中,我们使用 PUT API 来更新产品。当更新产品时,如果找不到产品,返回的响应消息是 “Product not found”。注意 **ProductNotFoundExceptio**n 异常类应当继承 **RuntimeException**。
package com.tutorialspoint.demo.exception;public class ProductNotfoundException extends RuntimeException {   private static final long serialVersionUID = 1L;}
    Controller Advice 类处理全局异常,如下所示。我们可以在这个类文件中定义任何 Exception Handler 方法。
package com.tutorialspoint.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;@ControllerAdvicepublic class ProductExceptionController {   @ExceptionHandler(value = ProductNotfoundException.class)   public ResponseEntity<Object> exception(ProductNotfoundException exception) {      return new ResponseEntity<>("Product not found", HttpStatus.NOT_FOUND);   }}
    下面的 Product Service API controller 文件更新产品。如果产品不存在,就抛出 ProductNotFoundException 类。
package com.tutorialspoint.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.tutorialspoint.demo.exception.ProductNotfoundException;import com.tutorialspoint.demo.model.Product;@RestControllerpublic 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);   }}
    **主 Spring Boot 应用类**文件如下:
package com.tutorialspoint.demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class DemoApplication {   public static void main(String[] args) {      SpringApplication.run(DemoApplication.class, args);   }}
    **产品 POJO 类** 如下:
package com.tutorialspoint.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 build – pom.xml** 代码如下所示:

<?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   http://maven.apache.org/xsd/maven-4.0.0.xsd">      <modelVersion>4.0.0</modelVersion>   <groupId>com.tutorialspoint</groupId>   <artifactId>demo</artifactId>   <version>0.0.1-SNAPSHOT</version>   <packaging>jar</packaging>   <name>demo</name>   <description>Demo project for Spring Boot</description>   <parent>      <groupId>org.springframework.boot</groupId>      <artifactId>spring-boot-starter-parent</artifactId>      <version>1.5.8.RELEASE</version>      <relativePath/>   </parent>   <properties>      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>      <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>      <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>      </dependency>   </dependencies>   <build>      <plugins>         <plugin>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-maven-plugin</artifactId>         </plugin>      </plugins>   </build>   </project>
    Gradle Build – build.gradle 代码如下:
buildscript {   ext {      springBootVersion = '1.5.8.RELEASE'   }   repositories {      mavenCentral()   }   dependencies {      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")   }}apply plugin: 'java'apply plugin: 'eclipse'apply plugin: 'org.springframework.boot'group = 'com.tutorialspoint'version = '0.0.1-SNAPSHOT'sourceCompatibility = 1.8repositories {   mavenCentral()}dependencies {   compile('org.springframework.boot:spring-boot-starter-web')   testCompile('org.springframework.boot:spring-boot-starter-test')}
你可以使用 Maven 或 Gradle 命令构建 JAR 并运行 Spring Boot 应用:
Maven 命令如下:
mvn clean install
“BUILD SUCCESS” 之后,你可以在 target 目录下找到 JAR 文件。
Gradle 可以使用如下命令:
gradle clean build
“BUILD SUCCESSFUL” 后,你可以在 build/libs 目录下找到 JAR 文件。
你可以使用下面的命令运行 JAR 文件。
java –jar <JARFILE>
在 Tomcat 8080 端口启动应用,如下所示:
![](https://p1-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/4368957acb164c33bcf529761baee5d8~tplv-k3u1fbpfcp-zoom-1.image)
现在,在 POSTMAN 应用中单击下面的 URL,你可以看到如下输出:
更新 URL: [http://localhost:8080/products/3](http://localhost:8080/products/3)
![](https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/e5fe89758b0841f584bcd1bf6da7f5de~tplv-k3u1fbpfcp-zoom-1.image)