编程软件

IDEA2023以上、Maven3.8、JDK21

创建Spring Boot工程

新建项目

删除无用文件

删除test目录

删除resource里面的static和template文件夹

精简pom.xml

<?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>3.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.example</groupId>
    <artifactId>springdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springdemo</name>
    <description>springdemo</description>

    <properties>
        <java.version>21</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

项目结构分析

target：是源码编译后的文件
pom.xml：定义Springbot的所有依赖项，springboot加载的时候会扫描这个文件的所有依赖项
SpringBoot里面内置了Tomcat

将application.properties重命名为application.yml

server:
  port: 9999

启动Spring Boot工程

运行SpringdemoApplication.java启动springboot工程

写一个测试接口say：hello

controller/WebController.java

package org.example.springdemo.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class WebController {

    //表示这是一个Get请求的接口
    @GetMapping("/hello")       //接口路径,全局唯一
    public String hello() {
        return "Hello World!";      //接口的返回值
    }
}

统一返回包装类Result

包装类：作用是统一后端返回的数据类型，code是作为前端判断请求成功的一句，msg是错误信息，data是返回给前端的数据

package org.example.springdemo.common;

public class Result {
    private String code;
    private Object data;
    private String msg;

    public static Result success(){
        Result result = new Result();
        result.setCode("200");
        result.setMsg("请求成功");
        return result;
    }

    public static Result success(Object data){
        Result result = new Result();
        result.setCode("200");
        result.setData(data);
        result.setMsg("请求成功");
        return result;
    }

    public static Result error(String msg){
        Result result = new Result();
        result.setCode("500");
        result.setMsg(msg);
        return result;
    }

    public static Result error(String code, String msg){
        Result result = new Result();
        result.setCode(code);
        result.setMsg(msg);
        return result;
    }

    public String getCode() {
        return code;
    }

    public Object getData() {
        return data;
    }

    public String getMsg() {
        return msg;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

500错误：常见的系统的错误

抛出这些错误非常不友好，我们应该使用统一的处理方式

全局异常处理器

GlobalExceptionHandler

package org.example.springdemo.exception;

import org.example.springdemo.common.Result;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;


/*
* 全局异常捕获器
*/
@ControllerAdvice("org.example.springdemo.controller")
public class GlobalExceptionHandler {
    private static final Logger log= LoggerFactory.getLogger(GlobalExceptionHandler.class);

    @ExceptionHandler(Exception.class)
    @ResponseBody   //将result对象转换成json的格式，返回出来
    public Result error(Exception e){
        log.error("系统异常", e);
        return Result.error("系统异常");
    }
}

自定义异常

CustomException

package org.example.springdemo.exception;

/**
 * 自定义异常类
 * 运行时异常
 */

public class CustomerException extends RuntimeException{
    private String code;
    private String msg;

    public CustomerException(String code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public CustomerException(String msg) {
        this.code = "500";
        this.msg = msg;
    }

    public CustomerException() {}

    public String getCode() {
        return code;
    }

    public String getMsg() {
        return msg;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

最终版全局异常

package org.example.springdemo.exception;

import org.example.springdemo.common.Result;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;


/*
* 全局异常捕获器
*/
@ControllerAdvice("org.example.springdemo.controller")
public class GlobalExceptionHandler {
    private static final Logger log= LoggerFactory.getLogger(GlobalExceptionHandler.class);

    @ExceptionHandler(Exception.class)
    @ResponseBody   //将result对象转换成json的格式，返回出来
    public Result error(Exception e){
        log.error("系统异常", e);
        return Result.error("系统异常");
    }

    @ExceptionHandler(CustomerException.class)
    @ResponseBody   //将result对象转换成json的格式，返回出来
    public Result customerError(CustomerException e){
        log.error("自定义错误", e);
        return Result.error(e.getCode(),e.getMsg());
    }
}