Java SpringBoot高級用法詳解

<?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>
<!--  該配置表示Maven坐標  -->
<!--  項目的組id  -->
    <groupId>com.jt</groupId>
<!--  項目名稱  -->
    <artifactId>springboot_demo1</artifactId>
<!--  項目版本號 -->
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_demo1</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>2.4.1</spring-boot.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <!--  SpringBoot的啟動項   wep  相當於引入MVC框架
                    思想："開箱即用"！！！
                    說明: 隻需要引入jar包,簡單的配置即可以使用該功能
                 -->
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
 
    <dependencyManagement>
        <dependencies>
            <!--相當於繼承瞭一個父級-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <!--通過pom標識 是一個父級 -->
                <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>2.4.1</version>
                <configuration>
                    <mainClass>com.jt.SpringbootDemo1Application</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
 
</project>

#YML文件的語法
#1，數據結構  key-value結構
#2，寫法：    key:(空格)value
#3，層及代碼結構，註意縮進
#4，字符集 文件讀取時，默認采取UTF-8編碼 可以寫中文
# 規則： 命名時最好指定前綴.
server:
  port: 8080
  # 指定業務的key
mysql:
  Username: root|
  Password: root||

package com.jt;
 
//import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
//import org.springframework.web.bind.annotation.RequestMapping;
 
@SpringBootApplication
public class SpringbootDemo1Application {
 
    public static void main(String[] args) {
        SpringApplication.run(SpringbootDemo1Application.class, args);
    }
 
    }

package com.jt.contraller;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
/**
 * 說明:
 *  1.將該類交給Spring容器管理
 *  2.SpringMVC負責調用該對象接收用戶的請求.
 *  3.將業務處理之後的結果,為頁面返回JSON數據.
 *  @ResponseBody作用: 將數據轉化為JSON串
 */
@RestController
public class JDBCController {
    //${key} Spring提供的springel表達式 簡稱為:spel表達式
    //語法: 從spring容器內部獲取key,動態為屬性賦值.
    @Value("${mysql.username}")
    String username;    // = "root|";
    @Value("${mysql.password}")
    String password;    // = "root";
 
    @RequestMapping("/getMsg")
    public String getMsg() {
        return "你好數據庫:" + username + password;
    }
}

#默認ISO-8859-1 中文必定亂碼
mysql.username2=mysql數據庫
mysql.password2=你猜猜

package com.jt.contraller;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.PropertySource;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * 說明:
 *  1.將該類交給Spring容器管理
 *  2.SpringMVC負責調用該對象接收用戶的請求.
 *  3.將業務處理之後的結果,為頁面返回JSON數據.
 *  @ResponseBody作用: 將數據轉化為JSON串
 *
 *  propertySource:  value屬性指定路徑
 *                   encoding屬性指定配置文件編碼格式
 */
@RestController
@PropertySource(value="classpath:/mysql.properties",encoding = "UTF-8")
public class JDBCContraller {
    /**
     * 難點: 如何將pro文件交給Spring容器管理????
     * 解決方案: @PropertySource("xxxxxx/xxx.properties") 指定配置文件交給Spring
     *          容器管理
     */
    @Value("${mysql.username2}")
    private String username2;
    @Value("${mysql.password2")
    private String password2;
 
    @RequestMapping("/getMsg2")
    public String getMsg2(){
 
        return "你好數據庫:"+ username2 +password2;
    }
}