一、前言
在开发中,有时我们可能会需要获取SQL中的表名,那么因为不同的数据源类型SQL会存在部分差异,那么我们就可以使用alibaba 的druid包实现不同的数据源类型的sql解析。
二、引入相关maven依赖
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.2.8</version>
</dependency>
三、通过工具类SqlUtils实现对SQL的解析。
public class QualitySqlUtils {
/**
* 根据sql及数据源类型获取表名
*/
public static List<String> getSelectSqlTable(String sql, String dbType) {
List<String> tableList = new ArrayList<>();
List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
SchemaStatVisitor visitor;
for (SQLStatement sqlStatement : stmtList) {
if (DbType.mysql.name().equalsIgnoreCase(dbType)) {
visitor = new MySqlSchemaStatVisitor();
} else if (DbType.hive.name().equalsIgnoreCase(dbType)) {
visitor = new HiveSchemaStatVisitor();
} else if (DbType.postgresql.name().equalsIgnoreCase(dbType)) {
visitor = new PGSchemaStatVisitor();
} else if (DbType.oracle.name().equalsIgnoreCase(dbType)) {
visitor = new OracleSchemaStatVisitor();
} else {
visitor = new SchemaStatVisitor(DbType.of(dbType));
}
sqlStatement.accept(visitor);
Map<TableStat.Name, TableStat> tables = visitor.getTables();
for (Map.Entry<TableStat.Name, TableStat> entry: tables.entrySet()){
String value = entry.getValue().toString();
if (StringUtils.isNotBlank(value)) {
tableList.add(entry.getKey().getName());
}
}
}
return tableList;
}
/**
* 根据sql获取查询的字段
*/
public static Map<String, String> getSelectSqlColumn(String sql, String dbType) {
Map<String, String> columnMap = new HashMap<>();
List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
for (int i = 0; i < stmtList.size(); i++) {
SQLStatement stmt = stmtList.get(i);
if (stmt instanceof SQLSelectStatement) {
SQLSelectStatement sqlSelectStatement = (SQLSelectStatement) stmt;
SQLSelect select = sqlSelectStatement.getSelect();
SQLSelectQueryBlock query = (SQLSelectQueryBlock) select.getQuery();
List<SQLSelectItem> selectList = query.getSelectList();
selectList.forEach(item->{
columnMap.put(item.getExpr().toString(), item.getAlias());
});
}
}
return columnMap;
}
}
三、测试结果
public class testDemo{
public static void main(String[] args) {
String sql = "select t.* from table1 as t left join table2 t2 on t.id = t2.id";
List<String> tableList =getSelectSqlTable(sql, "mysql");
System.out.println("获取到的表名: "+tableList);
}
}
运行结果如下:
大家感兴趣可以尝试下。