处理API中的异常和错误并向客户端发送正确的响应对企业应用程序有利.在本章中,我们将学习如何处理Spring Boot中的异常.
在继续进行异常处理之前,让我们了解以下注释.
@ControllerAdvice是一个注释,用于全局处理异常.
@ExceptionHandler是一个注释,用于处理特定异常并将自定义响应发送到客户端.
您可以使用以下代码创建@ControllerAdvice类来处理异常全局 :
package com.it1352.demo.exception; import org.springframework.web.bind.annotation.ControllerAdvice; @ControllerAdvice public class ProductExceptionController { }
定义一个扩展RuntimeException类的类.
package com.it1352.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,如图所示.此方法应该用于编写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中抛出异常.
@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PUT API更新产品.此处,在更新产品时,如果未找到产品,则将响应错误消息返回为"未找到产品".请注意, ProductNotFoundException 异常类应该扩展 RuntimeException .
package com.it1352.demo.exception; public class ProductNotfoundException extends RuntimeException { private static final long serialVersionUID = 1L; }
下面给出了全局处理异常的Controller Advice类.我们可以在这个类文件中定义任何Exception Handler方法.
package com.it1352.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); } }
下面给出了Product Service API控制器文件以更新产品.如果找不到产品,则会抛出 ProductNotFoundException 类.
package com.it1352.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.it1352.demo.exception.ProductNotfoundException; import com.it1352.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); } }
主Spring Boot应用程序类文件的代码在下面和下面给出;
package com.it1352.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类代码低于 :
package com.it1352.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 的代码如下所示 :
<?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.it1352</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 的代码在下面和下面给出;
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.it1352' version = '0.0.1-SNAPSHOT' sourceCompatibility = 1.8 repositories { mavenCentral() } dependencies { compile('org.springframework.boot:spring-boot-starter-web') testCompile('org.springframework.boot:spring-boot-starter-test') }
您可以创建可执行的JAR文件,并使用Maven或Gradl运行Spring Boot应用程序e命令 :
对于Maven,您可以使用以下命令 :
mvn clean install
在"BUILD SUCCESS"之后,你可以在目标目录下找到JAR文件.
对于Gradle,你可以使用以下命令 :
gradle clean build
之后"BUILD SUCCESSFUL",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>
这将在Tomcat端口8080上启动应用程序,如下所示 :
现在在POSTMAN应用程序中点击以下URL,你可以看到输出如下所示 :
更新网址:http://localhost:8080/products/3