java | （三十三）springboot

用idea创建了一个springboot架子（基于maven）

访问网站及配置数据源

数据源的配置在application.properties中，生成项目中有默认的，如下：

# 应用名称
spring.application.name=demo
# 数据库驱动：
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 数据源名称
spring.datasource.name=defaultDataSource
# 数据库连接地址
spring.datasource.url=jdbc:mysql://localhost:3306/blue?serverTimezone=UTC
# 数据库用户名&密码：
spring.datasource.username=***
spring.datasource.password=***

web访问：需要@RestController和@RequestMapping

package com.example.demo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.sql.DataSource;

@RestController
@RequestMapping("/test")
public class TestController {
    
    
    @Autowired
    private DataSource dataSource;
    @RequestMapping("/dataSource")
    public String testDataSource(){
    
    
        System.out.println("数据源类型是：" + dataSource.getClass().getName());
        return "OK";
    }
}

在浏览器中输入：

结果：

@Transactional注解

@Transactional用来标识在类或类中的方法上。
标识在类上代表此类中所有非静态公共方法将应用数据库事务。
标识在方法上代表此方法将应用数据库事务；
@Transactional注解还定义了事务的隔离级别和传播行为，异常类型的配置，这些配置定义了事务如何执行，具有哪些特征

事务的隔离级别
DEFAUTL 值为-1，不执行事务
READ_UNCOMMITTED 值为1，未提交读，会产生脏读
READ_COMMITTED 值为2，读写提交，会产生不可重复读
PEATABLE_READ 值为4，可重复读，会产生幻读
SERIALIZABLE 值为8，串行化，最高级别，避免以上所有问题

例如：

package com.example.demo.service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Transactional;

public class DepartmentService {
    
    
    @Transactional(rollbackFor = java.lang.Exception.class,
            isolation = Isolation.READ_COMMITTED,timeout = 1)
    public int saveDepartment(){
    
    
        return 0;
    }
}

在psvm中要有EnableTransactionManagement

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;

//@SpringBootApplication

@SpringBootApplication
@EnableTransactionManagement
public class DemoApplication {
    
    

    public static void main(String[] args) {
    
    
        SpringApplication.run(DemoApplication.class, args);
    }

}

注意：这个注解和org.springframework的spring-tx有关，要引入

多文件配置

参考这篇
文件目录：

在application.properties要加入

spring.profiles.active=dev

application-dev.yml:(修改了端口号）

server:
  port: 8912

结果：

使用了覆盖原有的配置的dev作为设置

springboot整合mybatis

注解方式

属性配置文件

#配置mybatis属性
mybatis.type-aliases-package=com.example.demo

方法的接口：

package com.example.demo.mappers;

import com.example.demo.domin.Department;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface DepartmentMapper {
    
    
    @Select("select * from department")
    List<Department> findAll();
}

Service层

package com.example.demo.service;
import com.example.demo.domin.Department;
import com.example.demo.mappers.DepartmentMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;

@Service
public class DepartmentServiceImp implements DepartmentService {
    
    

    @Autowired
    private DepartmentMapper departmentMapper;

    @Transactional(rollbackFor = java.lang.Exception.class,
            isolation = Isolation.READ_COMMITTED,timeout = 1)
    public int saveDepartment(){
    
    
        return 0;
    }


    @Override
    public List<Department> findAll() {
    
    
        return departmentMapper.findAll();
    }
}

Controller层：

package com.example.demo.controller;

import com.example.demo.domin.Department;
import com.example.demo.service.DepartmentServiceImp;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

@RestController
@RequestMapping("/test")
public class DepartmentController {
    
    
    @Autowired
    private DepartmentServiceImp departmentServiceImp;

    @RequestMapping("/findAll")
    public String findAll(){
    
    
        List<Department> departmentList = departmentServiceImp.findAll();
        System.out.println(departmentList.size());
        return "ok";
    }
}

来访问一下：

结果略
一些注意的坑：
遇到：
这里的情况
需要在启动文件下加上

@EnableTransactionManagement(proxyTargetClass = true)

还有，配置数据库连接地址，是spring.datasource.jdbc-url，如果有问题，可能是写成了spring.datasource.url
最后，有一下错误，

java.sql.SQLException: 不支持的字符集 (在类路径中添加 orai18n.jar): ZHS16GBK

根据这篇文章来搞：
这篇文章

根据xml文件配置

xml：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.demo.domin.Emp">
    <select id="findEmp" resultType="emp" statementType="PREPARED">
        select * from emp
    </select>
</mapper>

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.transaction.annotation.EnableTransactionManagement;

//@SpringBootApplication

@SpringBootApplication
//@EnableTransactionManagement
@EnableTransactionManagement(proxyTargetClass = true)
@MapperScan(value = {
    
    "com.example.demo.mappers","com.example.demo.*.mappers"})
public class DemoApplication {
    
    

    public static void main(String[] args) {
    
    
        SpringApplication.run(DemoApplication.class, args);
    }

}

package com.example.demo.mappers;

import com.example.demo.domin.Department;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface DepartmentMapper {
    
    
    @Select("select * from department")
    List<Department> findAll();
}

package com.example.demo.emp.service;

import com.example.demo.domin.Emp;
import com.example.demo.emp.mappers.EmployeeMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class EmpServiceImp implements EmpService{
    
    

    @Autowired
    private EmployeeMapper employeeMapper;

    @Override
    public List<Emp> findEmp() {
    
    
        return employeeMapper.findEmp();
    }
}

package com.example.demo.emp.Controller;

import com.example.demo.domin.Emp;
import com.example.demo.emp.service.EmpService;

import com.example.demo.emp.service.EmpServiceImp;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.ModelAndView;

import java.util.List;

@Controller
@RequestMapping("/emp")
public class EmpController {
    
    
    @Autowired
    private EmpService empServiceImp;
    @RequestMapping("/findEmp")
    public ModelAndView findEmp(){
    
    
        List<Emp> list = empServiceImp.findEmp();
        System.out.println(list.size());
        ModelAndView view = new ModelAndView("com/example/demo/page/index.jsp");

        return view;
    }
}

MyBatis Plus

简称MP，是myBatis的一个功能增强组件，唯一目的简化sql代码编写，提高效率，提供更多可以选择的简便操作数据API，它不对myBatis做任何更改，springboot提供了对MP的方便整合

配置：在pow加入

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

配置lombok
配置lombok后，可以在类中不用生成set和get方法，以及一些其它方法
pow.xml

            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.16.10</version>
            </dependency>

建立Mapper（之前用了这个Mapper写了findAll方法，这里的findAll与示例无关）

package com.example.demo.mappers;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.demo.domin.Department;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper
public interface DepartmentMapper extends BaseMapper<Department> {
    
    
    @Select("select * from department")
    List<Department> findAll();
}

查询方法

在建立了Mapper，这个Mapper接口继承了BaseMapper，可以免费使用里面的方法，而不用写select语句了
DepartmentService

    @Autowired
    private DepartmentMapper departmentMapper;


    @Override
    public List<Department> queryDepList(){
    
    
        return departmentMapper.selectList(null);
    }

Controller

@RequestMapping("/findAll2")
public String queryDep(){
    
    
    List<Department> departmentList = departmentServiceImp.queryDepList();
    System.out.println(departmentList.size());
    departmentList.forEach(System.out::println);
    return "ook";
}

结果：

删除

domin
注意，要用@TableId注解主键，不然不会根据主键删除成功

package com.example.demo.domin;

import com.baomidou.mybatisplus.annotation.TableId;
import lombok.Data;

import java.util.Date;

@Data(staticConstructor = "newInstance")
public class Department {
    
    
    @TableId(value = "ID")
    private String id;
    private String name;
    private String code;
    private Date newdate;
    private String descs;
   
}

service层

    @Autowired
    private DepartmentMapper departmentMapper;
    @Override
    public int deleteById(String id) {
    
    
        return departmentMapper.deleteById(id);
    }

controller层

@RequestMapping("/delete")
public String deleteDep(){
    
    
    System.out.println(departmentServiceImp.deleteById("depid8"));
    departmentServiceImp.queryDepList().forEach(System.out::println);
    return "deleteOK";
}

插入

使用静态构造方法：
domin同上

package com.example.demo.domin;

import com.baomidou.mybatisplus.annotation.TableId;
import lombok.Data;

import java.util.Date;

@Data(staticConstructor = "newInstance")
public class Department {
    
    
    @TableId(value = "ID")
    private String id;
    private String name;
    private String code;
    private Date newdate;
    private String descs;
}

service（节选，下同）

    @Override
    public int insertDep(Department department) {
    
    
        return departmentMapper.insert(department);
    }

controller
注意，这里用了构造方法来创建实例，这是设置好的

    @RequestMapping("/insert")
    public int insertDep(){
    
    
        Department department = Department.newInstance();
        department.setId("DEPID1009");
        department.setCode("7788");
        department.setName("卡卡部");
        department.setNewdate(new Date());
        department.setDescs("案例");
        return departmentServiceImp.insertDep(department);
    }

结果：数据库插入一条数据

查询一条记录（根据id）

    @Override
    public Department selectById(String id) {
    
    
        return departmentMapper.selectById(id);
    }

查询返回Map

新建xml文件，注意namespace

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.demo.mappers.DepartmentMapper">
    <select id="findDepMap" resultType="map">
        select id,name,newdate from department
    </select>
</mapper>

DepartmentMapper.java

package com.example.demo.mappers;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.demo.domin.Department;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Map;

@Mapper
public interface DepartmentMapper extends BaseMapper<Department> {
    
    
    @Select("select * from department")
    List<Department> findAll();

    public List<Map<String,Object>> findDepMap();//与xml一致
}

DepartmentServiceImp.java

    @Override
    public List<Map<String, Object>> findDepMap() {
    
    
        List<Map<String,Object>> list = departmentMapper.findDepMap();
        System.out.println("查询的总语句数："+list.size());
        return list;
    }

Controller.java

    @RequestMapping("sm")
    public String selectMap(){
    
    
        List<Map<String,Object>> list = departmentServiceImp.findDepMap();
        list.get(0).keySet().forEach(System.out::println);//全是大写
        return "yes";
    }

结果:

可以看到，键名都是大写