MyBatis Generator使用com.mysql.cj.jdbc.Driver遇到的问题

MyBatis Generator使用com.mysql.cj.jdbc.Driver

Mybatis Generator 1.3.5

新建了一个decision库，并创建了一张user表

import org.apache.commons.lang3.StringUtils;
import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.*;
import org.mybatis.generator.internal.DefaultShellCallback;
import com.google.common.base.CaseFormat;
import java.text.SimpleDateFormat;
import java.util.*;
import static com.tydt.decision.core.ProjectConstant.*;

public class CodeGenerator {
    //JDBC配置，请修改为你项目的实际配置
    private static final String JDBC_URL = "jdbc:mysql://localhost:3306/decision?serverTimezone=GMT%2B8&characterEncoding=utf8";
    private static final String JDBC_USERNAME = "root";
    private static final String JDBC_PASSWORD = "root";
    private static final String JDBC_DIVER_CLASS_NAME = "com.mysql.cj.jdbc.Driver";

    private static final String PROJECT_PATH = System.getProperty("user.dir");//项目在硬盘上的基础路径
    private static final String TEMPLATE_FILE_PATH = PROJECT_PATH + "/src/test/resources/generator/template";//模板位置

    private static final String JAVA_PATH = "/src/main/java"; //java文件路径
    private static final String RESOURCES_PATH = "/src/main/resources";//资源文件路径

    private static final String PACKAGE_PATH_SERVICE = packageConvertPath(SERVICE_PACKAGE);//生成的Service存放路径
    private static final String PACKAGE_PATH_SERVICE_IMPL = packageConvertPath(SERVICE_IMPL_PACKAGE);//生成的Service实现存放路径
    private static final String PACKAGE_PATH_CONTROLLER = packageConvertPath(CONTROLLER_PACKAGE);//生成的Controller存放路径

    private static final String AUTHOR = "Beibei";//@author
    private static final String DATE = new SimpleDateFormat("yyyy/MM/dd").format(new Date());//@date

    public static void main(String[] args) {
        genCode("user");
        //genCodeByCustomModelName("输入表名","输入自定义Model名称");
    }

    /**
     * 通过数据表名称生成代码，Model 名称通过解析数据表名称获得，下划线转大驼峰的形式。
     * 如输入表名称 "t_user_detail" 将生成 TUserDetail、TUserDetailMapper、TUserDetailService ...
     * @param tableNames 数据表名称...
     */
    public static void genCode(String... tableNames) {
        for (String tableName : tableNames) {
            genCodeByCustomModelName(tableName, null);
        }
    }

    /**
     * 通过数据表名称，和自定义的 Model 名称生成代码
     * 如输入表名称 "t_user_detail" 和自定义的 Model 名称 "User" 将生成 User、UserMapper、UserService ...
     * @param tableName 数据表名称
     * @param modelName 自定义的 Model 名称
     */
    public static void genCodeByCustomModelName(String tableName, String modelName) {
        genModelAndMapper(tableName, modelName);
    }


    public static void genModelAndMapper(String tableName, String modelName) {
        Context context = new Context(ModelType.FLAT);
        context.setId("Potato");
        context.setTargetRuntime("MyBatis3Simple");
        context.addProperty(PropertyRegistry.CONTEXT_BEGINNING_DELIMITER, "`");
        context.addProperty(PropertyRegistry.CONTEXT_ENDING_DELIMITER, "`");

        JDBCConnectionConfiguration jdbcConnectionConfiguration = new JDBCConnectionConfiguration();
        jdbcConnectionConfiguration.setConnectionURL(JDBC_URL);
        jdbcConnectionConfiguration.setUserId(JDBC_USERNAME);
        jdbcConnectionConfiguration.setPassword(JDBC_PASSWORD);
        jdbcConnectionConfiguration.setDriverClass(JDBC_DIVER_CLASS_NAME);
        context.setJdbcConnectionConfiguration(jdbcConnectionConfiguration);

        PluginConfiguration pluginConfiguration = new PluginConfiguration();
        pluginConfiguration.setConfigurationType("tk.mybatis.mapper.generator.MapperPlugin");
        pluginConfiguration.addProperty("mappers", MAPPER_INTERFACE_REFERENCE);
        context.addPluginConfiguration(pluginConfiguration);

        JavaModelGeneratorConfiguration javaModelGeneratorConfiguration = new JavaModelGeneratorConfiguration();
        javaModelGeneratorConfiguration.setTargetProject(PROJECT_PATH + JAVA_PATH);
        javaModelGeneratorConfiguration.setTargetPackage(MODEL_PACKAGE);
        context.setJavaModelGeneratorConfiguration(javaModelGeneratorConfiguration);

        SqlMapGeneratorConfiguration sqlMapGeneratorConfiguration = new SqlMapGeneratorConfiguration();
        sqlMapGeneratorConfiguration.setTargetProject(PROJECT_PATH + RESOURCES_PATH);
        sqlMapGeneratorConfiguration.setTargetPackage("mapper");
        context.setSqlMapGeneratorConfiguration(sqlMapGeneratorConfiguration);

        JavaClientGeneratorConfiguration javaClientGeneratorConfiguration = new JavaClientGeneratorConfiguration();
        javaClientGeneratorConfiguration.setTargetProject(PROJECT_PATH + JAVA_PATH);
        javaClientGeneratorConfiguration.setTargetPackage(MAPPER_PACKAGE);
        javaClientGeneratorConfiguration.setConfigurationType("XMLMAPPER");
        context.setJavaClientGeneratorConfiguration(javaClientGeneratorConfiguration);

        TableConfiguration tableConfiguration = new TableConfiguration(context);
        tableConfiguration.setTableName(tableName);
        if (StringUtils.isNotEmpty(modelName))tableConfiguration.setDomainObjectName(modelName);
        tableConfiguration.setGeneratedKey(new GeneratedKey("id", "Mysql", true, null));
        context.addTableConfiguration(tableConfiguration);

        List<String> warnings;
        MyBatisGenerator generator;
        try {
            Configuration config = new Configuration();
            config.addContext(context);
            config.validate();

            boolean overwrite = true;
            DefaultShellCallback callback = new DefaultShellCallback(overwrite);
            warnings = new ArrayList<String>();
            generator = new MyBatisGenerator(config, callback, warnings);
            generator.generate(null);
        } catch (Exception e) {
            throw new RuntimeException("生成Model和Mapper失败", e);
        }

        if (generator.getGeneratedJavaFiles().isEmpty() || generator.getGeneratedXmlFiles().isEmpty()) {
            throw new RuntimeException("生成Model和Mapper失败：" + warnings);
        }
        if (StringUtils.isEmpty(modelName)) modelName = tableNameConvertUpperCamel(tableName);
        System.out.println(modelName + ".java 生成成功");
        System.out.println(modelName + "Mapper.java 生成成功");
        System.out.println(modelName + "Mapper.xml 生成成功");
    }

    private static String tableNameConvertUpperCamel(String tableName) {
        return CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, tableName.toLowerCase());

    }

    private static String packageConvertPath(String packageName) {
        return String.format("/%s/", packageName.contains(".") ? packageName.replaceAll("\\.", "/") : packageName);
    }
}

直接运行后输出

User.java 生成成功
UserMapper.java 生成成功
UserMapper.xml 生成成功

但是打开User.java，发现字段包括本地所有包换user表的字段

org.mybatis.generator.internal.db.DatabaseIntrospector

ResultSet rs = databaseMetaData.getColumns(localCatalog, localSchema,localTableName, "%");

localCatalog是null，在底层会执行SHOW DATABASES 得到所有的数据库

在连接中少配置了一个属性nullCatalogMeansCurrent=true

将连接配置的那句改为

JDBC_URL = "jdbc:mysql://localhost:3306/decision?serverTimezone=GMT%2B8&characterEncoding=utf8&nullCatalogMeansCurrent=true"

修改完后，重新运行，User.java里面的字段只是decision数据库里的user了，问题解决

nullCatalogMeansCurrent=true使用com.mysql.cj.jdbc.Driver这个驱动的时候，要加上这个属性。

在项目中不需要加，但是在使用Mybatis Generator时要加上。

原文地址：https://www.cnblogs.com/baby123/p/10439194.html