本篇文章为大家展示了mybatis plus中怎么自定义主键生成器IKeyGenerator，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。
1. 继承IKeyGenerator
计算
安全
数据库
网络和加速
企业服务
@Slf4j
@Component
public class MybatisKeyGenerator implements IKeyGenerator {
@Value("${server.worker-id}")
private Integer workerId;
@Value("${server.data-center-id}")
private Integer dataCenterId;
@Override
public String executeSql(String incrementerName) {
log.info("mybatis plus keyGenerator: " + incrementerName + "(" + workerId + "," + dataCenterId + ")");
long uid = new SnowflakeIdWorker(workerId, dataCenterId).nextId();
return "select " + uid + " from dual";
}
}2. 定义entity, 需要有@KeySequence注解，和IdType.INPUT或者IdType.ID_WORKER
@Data
@TableName("test1")
@KeySequence("mybatisKeyGenerator")
public class Test {
@TableId(type = IdType.INPUT)
private Long id;
private String name;
}3.测试:
@Autowired
private TestMapper testMapper;
@Override
public void run(String... args) throws Exception {
Test test = new Test();
test.setName("CCC"+ LocalDateTime.now());
testMapper.insert(test);
System.out.println(">>>> test:"+ test);
}源码查看：
1. com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration
// 从spring容器中获取IKeyGenerator
//注入主键生成器
if (this.applicationContext.getBeanNamesForType(IKeyGenerator.class, false,
false).length > 0) {
IKeyGenerator keyGenerator = this.applicationContext.getBean(IKeyGenerator.class);
globalConfig.getDbConfig().setKeyGenerator(keyGenerator);
}2. 在扫描实体时候，会扫描KeySequence注解
/* 开启了自定义 KEY 生成器 */
if (null != dbConfig.getKeyGenerator()) {
tableInfo.setKeySequence(clazz.getAnnotation(KeySequence.class));
}3. 插入数据时：com.baomidou.mybatisplus.core.injector.methods.Insert
// 表包含主键处理逻辑,如果不包含主键当普通字段处理
if (StringUtils.isNotEmpty(tableInfo.getKeyProperty())) {
if (tableInfo.getIdType() == IdType.AUTO) {
/** 自增主键 */
keyGenerator = new Jdbc3KeyGenerator();
keyProperty = tableInfo.getKeyProperty();
keyColumn = tableInfo.getKeyColumn();
} else {
// 如果有注解，则获取自定义的主键生成器
if (null != tableInfo.getKeySequence()) {
// 这里获取的就是注入的生成器，执行生成器接口executeSql，传入值为注解里面的value
keyGenerator = TableInfoHelper.genKeyGenerator(tableInfo, builderAssistant, sqlMethod.getMethod(), languageDriver);
keyProperty = tableInfo.getKeyProperty();
keyColumn = tableInfo.getKeyColumn();
}
}
}4.
/**
* <p>
* 自定义 KEY 生成器
* </p>
*/
public static KeyGenerator genKeyGenerator(TableInfo tableInfo, MapperBuilderAssistant builderAssistant,
String baseStatementId, LanguageDriver languageDriver) {
IKeyGenerator keyGenerator = GlobalConfigUtils.getKeyGenerator(builderAssistant.getConfiguration());
if (null == keyGenerator) {
throw new IllegalArgumentException("not configure IKeyGenerator implementation class.");
}
String id = baseStatementId + SelectKeyGenerator.SELECT_KEY_SUFFIX;
Class<?> resultTypeClass = tableInfo.getKeySequence().clazz();
StatementType statementType = StatementType.PREPARED;
String keyProperty = tableInfo.getKeyProperty();
String keyColumn = tableInfo.getKeyColumn();
// 执行语句keyGenerator.executeSql(tableInfo.getKeySequence().value())
SqlSource sqlSource = languageDriver.createSqlSource(builderAssistant.getConfiguration(),
keyGenerator.executeSql(tableInfo.getKeySequence().value()), null);
builderAssistant.addMappedStatement(id, sqlSource, statementType, SqlCommandType.SELECT, null, null, null,
null, null, resultTypeClass, null, false, false, false,
new NoKeyGenerator(), keyProperty, keyColumn, null, languageDriver, null);
id = builderAssistant.applyCurrentNamespace(id, false);
MappedStatement keyStatement = builderAssistant.getConfiguration().getMappedStatement(id, false);
SelectKeyGenerator selectKeyGenerator = new SelectKeyGenerator(keyStatement, true);
builderAssistant.getConfiguration().addKeyGenerator(id, selectKeyGenerator);
return selectKeyGenerator;
}上述内容就是mybatis plus中怎么自定义主键生成器IKeyGenerator，你们学到知识或技能了吗？如果还想学到更多技能或者丰富自己的知识储备，欢迎关注亿速云行业资讯频道。
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原文链接：https://my.oschina.net/wangxinxx/blog/5045134
