第一次

.gitignore

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+HELP.md
+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/

pom.xml

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+<?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>
+    <groupId>com.example</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>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <spring-boot.version>2.6.13</spring-boot.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+        </dependency>
+    </dependencies>
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-dependencies</artifactId>
+                <version>${spring-boot.version}</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                    <encoding>UTF-8</encoding>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>${spring-boot.version}</version>
+                <configuration>
+                    <mainClass>com.example.demo.DemoApplication</mainClass>
+                    <skip>true</skip>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>repackage</id>
+                        <goals>
+                            <goal>repackage</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

src/main/java/com/example/demo/DemoApplication.java

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+package com.example.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);
+    }
+
+}

src/main/java/com/example/demo/test/Test.java

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+package com.example.demo.test;
+
+import lombok.extern.log4j.Log4j2;
+
+import java.math.BigDecimal;
+
+@Log4j2
+public class Test {
+
+    public static void main(String[] args) {
+
+        BigDecimal num1 = new BigDecimal(10);
+        BigDecimal num2 = new BigDecimal(5);
+
+        //加法
+        BigDecimal add = num1.add(num2);
+        log.info("BigDecimal加法 ：num1+num2={}",add);
+
+        //减法
+        BigDecimal subtract = num1.subtract(num2);
+        log.info("BigDecimal减法 ：num1-num2={}",subtract);
+
+        //乘法
+        BigDecimal multiply = num1.multiply(num2);
+        log.info("BigDecimal乘法 ：num1*num2={}",multiply);
+
+        //除法
+        BigDecimal divide = num1.divide(num2);
+        log.info("BigDecimal除法 ：num1/num2={}",divide);
+    }
+
+
+
+}

src/test/java/com/example/demo/DemoApplicationTests.java

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+package com.example.demo;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class DemoApplicationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}