当下后端的开发上,对于数据库的操作从之前的ssh到ssm,现在springboot对spring中的各个组件的整合及简化配置。从操作后端的数据上从先前的hibernate到现在的mybatis,hibernate是一个对象关系映射框架,它将java对象与数据库表建立映射关系,是一个全自动的orm框架,hibernate以操作java中与数据库中的表对应的实体类来操作数据库。mybatis相对hibernate,以自己手写SQL来操作数据库,对比hibernate操作相对复杂一些,但同时的对数据库的操作能通过手写SQL来优化。mybatis-plus对mybatis的功能进一步加强,封装了基本的查询操作,减少了代码量,同时带有自己的代码生成器。
首先需要导入jar,下面是maven导包的xml代码
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plus-boot-starterartifactId>
<version>3.4.0version>
dependency>
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plus-generatorartifactId>
<version>3.4.0version>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-freemarkerartifactId>
dependency>
下面是代码自动生成的方法
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.core.exceptions.MybatisPlusException;
import com.baomidou.mybatisplus.core.toolkit.StringPool;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.generator.AutoGenerator;
import com.baomidou.mybatisplus.generator.InjectionConfig;
import com.baomidou.mybatisplus.generator.config.*;
import com.baomidou.mybatisplus.generator.config.po.TableInfo;
import com.baomidou.mybatisplus.generator.config.rules.NamingStrategy;
import com.baomidou.mybatisplus.generator.engine.FreemarkerTemplateEngine;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class CodeGenerator {
private static final String dbName = "数据库名";
private static final String driverClassName = "com.mysql.cj.jdbc.Driver";
private static final String dbUrl = "jdbc:mysql://127.0.0.1:3306/" + dbName + "?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2B8";
private static final String dbUsername = "数据库的账号";
private static final String dbPassword = "数据库的密码";
private static final String basePackageName = "包名";
private static final String author = "作者名";
// 是否开启swagger日志
private static final boolean useSwagger = false;
// 是否覆盖
private static final boolean isOverride = false;
/**
* 获取某个数据库中的所有表名
* @param dbName
* @return
* @throws Exception
*/
private static String[] getTables(String dbName) throws Exception {
List<String> tables = new ArrayList<>();
Connection connection = null;
PreparedStatement ps = null;
ResultSet resultSet = null;
try {
Class.forName(driverClassName);
connection = DriverManager.getConnection(dbUrl,dbUsername,dbPassword);
String sql = "select table_name from information_schema.tables where table_schema=?";
ps = connection.prepareStatement(sql);
ps.setString(1,dbName);
resultSet = ps.executeQuery();
while (resultSet.next()) {
tables.add(resultSet.getString("table_name"));
}
String[] result = tables.toArray(new String[tables.size()]);
return result;
} catch (Exception e) {
e.printStackTrace();
} finally {
if (resultSet != null) {
try {
resultSet.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (ps != null) {
try {
ps.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (connection != null) {
try {
connection.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
throw new Exception("数据库连接异常!");
}
/**
* 直接获取数据库中的所有表名然后自动生成
* 自动生成entity、mapper、service、controller的代码
* @throws Exception
*/
private static void generateAllInfo() throws Exception {
// 代码生成器
AutoGenerator mpg = new AutoGenerator();
// 全局配置
GlobalConfig gc = new GlobalConfig();
String projectPath = System.getProperty("user.dir");
gc.setOutputDir(projectPath + "/src/main/java");
gc.setAuthor(author);
gc.setOpen(false);
gc.setSwagger2(useSwagger); //实体属性 Swagger2 注解
gc.setFileOverride(isOverride); // 是否覆盖
gc.setServiceName("%sService"); //去Service的I前缀
mpg.setGlobalConfig(gc);
// 数据源配置
DataSourceConfig dsc = new DataSourceConfig();
dsc.setUrl(dbUrl);
dsc.setDriverName(driverClassName);
dsc.setUsername(dbUsername);
dsc.setPassword(dbPassword);
dsc.setDbType(DbType.MYSQL);
mpg.setDataSource(dsc);
// 包配置
PackageConfig pc = new PackageConfig();
pc.setModuleName(null);
pc.setParent(basePackageName);
mpg.setPackageInfo(pc);
// 自定义配置
InjectionConfig cfg = new InjectionConfig() {
@Override
public void initMap() {}
};
// 如果模板引擎是 freemarker
String templatePath = "/templates/mapper.xml.ftl";
// 如果模板引擎是 velocity
// String templatePath = "/templates/mapper.xml.vm";
// 自定义输出配置
List<FileOutConfig> focList = new ArrayList<>();
// 自定义配置会被优先输出
focList.add(new FileOutConfig(templatePath) {
@Override
public String outputFile(TableInfo tableInfo) {
// 自定义输出文件名 , 如果你 Entity 设置了前后缀、此处注意 xml 的名称会跟着发生变化!!
return projectPath + "/src/main/resources/mapper/" +
"/" + tableInfo.getEntityName() + "Mapper" + StringPool.DOT_XML;
}
});
cfg.setFileOutConfigList(focList);
mpg.setCfg(cfg);
// 配置模板
TemplateConfig templateConfig = new TemplateConfig();
templateConfig.setXml(null);
mpg.setTemplate(templateConfig);
// 策略配置
StrategyConfig strategy = new StrategyConfig();
strategy.setNaming(NamingStrategy.underline_to_camel);
strategy.setColumnNaming(NamingStrategy.underline_to_camel);
strategy.setEntityLombokModel(true);
strategy.setRestControllerStyle(true);
strategy.setInclude(getTables(dbName));
strategy.setControllerMappingHyphenStyle(true);
mpg.setStrategy(strategy);
mpg.setTemplateEngine(new FreemarkerTemplateEngine());
mpg.execute();
}
public static void main(String[] args) {
try {
generateAllInfo();
} catch (Exception e) {
e.printStackTrace();
}
}
}