前言

经过打工人的不懈努力，终于敲出了多层封装的安卓前后端分离项目的雏形。

前期准备

开发环境：

(1)jdk1.8
(2)Android stdio 4.1 (包含自带的Gradle)
(3)IntelliJ IDEA 2020.2.3 x64 (包含配置好的的Maven)

项目框架及依赖

安卓用了OKHttp
后端用了springboot+mybatis-plus

安卓前端的gradle依赖

dependencies {

    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.squareup.okhttp3:okhttp:4.2.2'
    implementation 'com.google.code.gson:gson:2.7'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
}
    

springboot项目的maven依赖

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.3.2</version>
        </dependency>

        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity</artifactId>
            <version>1.7</version>
        </dependency>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
        </dependency>


    </dependencies>

后端搭建

1.通过mybatis-plus模板生成

根据数据库中的表user创建

生成mvc代码：Generate.java（要放在包的最外层，与初始的springboot启动类平级的位置,例如：放在com.example下）

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.config.DataSourceConfig;
import com.baomidou.mybatisplus.generator.config.GlobalConfig;
import com.baomidou.mybatisplus.generator.config.PackageConfig;
import com.baomidou.mybatisplus.generator.config.StrategyConfig;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;

import java.util.ArrayList;
import java.util.List;

public class Generate {
   
    
    public static void main(String[] args) {
   
    
        
        //创建generator对象
        AutoGenerator autoGenerator = new AutoGenerator();
        //数据源
        DataSourceConfig dataSourceConfig = new DataSourceConfig();
        dataSourceConfig.setDbType(DbType.MYSQL);
        dataSourceConfig.setDriverName("com.mysql.cj.jdbc.Driver");
        dataSourceConfig.setUsername("root");
        dataSourceConfig.setPassword("123456");
        dataSourceConfig.setUrl("jdbc:mysql://localhost:3306/dbName");
        autoGenerator.setDataSource(dataSourceConfig);
        //全局配置
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setOutputDir(System.getProperty("user.dir")+"/src/main/java");
        globalConfig.setAuthor("admin");
        globalConfig.setOpen(false);
        globalConfig.setServiceName("%sService");
        autoGenerator.setGlobalConfig(globalConfig);
        //包信息
        PackageConfig packageConfig = new PackageConfig();
        packageConfig.setParent("com.example");//包名
        packageConfig.setEntity("entity");
        packageConfig.setMapper("mapper");
        packageConfig.setService("service");
        packageConfig.setServiceImpl("service.impl");
        packageConfig.setController("controller");
        autoGenerator.setPackageInfo(packageConfig);
        //策略配置
        StrategyConfig strategyConfig = new StrategyConfig();
        String tablesName="user";
        strategyConfig.setInclude(tablesName);
        
        strategyConfig.setNaming(NamingStrategy.underline_to_camel);
        strategyConfig.setColumnNaming(NamingStrategy.underline_to_camel);
        strategyConfig.setEntityLombokModel(true);
        autoGenerator.setStrategy(strategyConfig);
        //运行
        autoGenerator.execute();
    }
}

生成结果：（没有util）

创建一个结果类Result，用来装结果集（第三个参数装json字符串）

import lombok.Data;
import lombok.EqualsAndHashCode;

@Data
@EqualsAndHashCode(callSuper = false)
public class Result {
   
    
	private int code;
	private String msg;
	private String result;
	public void setSuccess(String msg, String result){
   
    
		this.code=200;
		this.msg="success-"+msg;
		this.result=result;
	}
	public void setInfo(String msg, String result){
   
    
		this.code=400;
		this.msg="warning-"+msg;
		this.result=result;
	}
}

配置文件application改成yml后缀

application.yml内容为：

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/db_name
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:com/example/mapper/xml/*.xml
server:
  port: 8081

控制层：

import com.campus.book.entity.Result;
import com.campus.book.entity.User;
import com.campus.book.service.UserService;
import com.campus.book.util.JsonBean;
import com.google.gson.Gson;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;


import java.io.Serializable;

@RestController
@RequestMapping("//user")
public class UserController {
   
    
	@Autowired
	private UserService userService;

	Gson gson= new GsonBuilder().serializeNulls().create();
	Result result=new Result();

	@PostMapping("/insert")
	public Result insert(String json){
   
    
		User user=null;
		try{
   
    
			user=gson.fromJson(json,User.class);
		}catch (Exception e){
   
    
			e.printStackTrace();
		}
		if(userService.getById(user.getId())!=null){
   
    //id重复！
			result.setInfo("该账号已注册！",null);
		}else{
   
    
			userService.save(user);
			result.setSuccess("注册成功！",gson.toJson(user));
		}
		return result;
	}

	@DeleteMapping("/delete/{id}")
	public Result delete(@PathVariable("id") Serializable id) {
   
    
		result.setSuccess("删除成功！", null);
		boolean is=this.userService.removeById(id);
		if(is){
   
    

		}else{
   
    
			result.setInfo("删除失败！",null);
		}
		return result;
	}

	@PutMapping("/update")
	public Result update(String json) {
   
    
		result.setInfo("更改失败！",json);
		User user=null;
		try{
   
    
			user=gson.fromJson(json,User.class);
			if(this.userService.updateById(user)){
   
    
				result.setSuccess("更改成功！",gson.toJson(userService.getById(user.getId())));
			}
		}catch (Exception e){
   
    
			e.printStackTrace();
		}
		return result;
	}

	@GetMapping("/list")
	public Result list() {
   
    
		result.setSuccess("查询成功！", gson.toJson(this.userService.list()));
		return result;
	}

	@GetMapping("/line/{id}")
	public Result getUser(@PathVariable("id") Serializable id){
   
    
		User user=userService.getById(id);
		if(user!=null){
   
    //存在
			result.setSuccess("查询成功！",gson.toJson(user));
		}else{
   
    //不存在
			result.setSuccess("没有找到相关数据！",null);
		}
		return result;