ClassInstance

在使用阿里canal时同步数据，由于现在的canal-adapter满足不了公司需求，于是我用canal-client自己实现同步，这里需要解析ddl语句，涉及到自己写sql解析有点麻烦，所以找了一下这种组件，能用组件的就用组件，不能的就自己写了，这里分享一下，我用的是阿里的druid，他里面有解析sql的代码，直接拿来用。

maven引入：

	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>5.1.33</version>
	</dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.9</version>
        </dependency>

package parse;

import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.alibaba.druid.sql.SQLUtils;
import com.alibaba.druid.sql.ast.SQLStatement;
import com.alibaba.druid.sql.dialect.postgresql.visitor.PGSchemaStatVisitor;
import com.alibaba.druid.stat.TableStat.*;
import com.alibaba.druid.stat.*;
import com.alibaba.druid.util.JdbcConstants;
 

public class testparse {
 
    public static void main(String[] args) {
 
        String sql= ""
                + "insert into tar select * from boss_table bo, ("
                    + "select a.f1, ff from emp_table a "
                    + "inner join log_table b "
                    + "on a.f2 = b.f3"
                    + ") f "
                    + "where bo.f4 = f.f5 "
                    + "group by bo.f6 , f.f7 having count(bo.f8) > 0 "
                    + "order by bo.f9, f.f10;"
                    + "select func(f) from test1; "
                    + "";
        String dbType = JdbcConstants.POSTGRESQL;
 
        //格式化输出
        String result = SQLUtils.format(sql, dbType);
        System.out.println(result); // 缺省大写格式
        List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
 
        //解析出的独立语句的个数
        System.out.println("size is:" + stmtList.size());
        for (int i = 0; i < stmtList.size(); i++) {
 
            SQLStatement stmt = stmtList.get(i);
            
            PGSchemaStatVisitor visitor = new PGSchemaStatVisitor();
            stmt.accept(visitor);
            Map<String, String> aliasmap = visitor.getAliasMap();
            for (Iterator iterator = aliasmap.keySet().iterator(); iterator.hasNext();) {
                String key = iterator.next().toString();
                System.out.println("[ALIAS]" + key + " - " + aliasmap.get(key));
            }
            Set<Column> groupby_col = visitor.getGroupByColumns();
            //
            for (Iterator iterator = groupby_col.iterator(); iterator.hasNext();) {
                Column column = (Column) iterator.next();
                System.out.println("[GROUP]" + column.toString());
            }
            //获取表名称
            System.out.println("table names:");
            Map<Name, TableStat> tabmap = visitor.getTables();
            for (Iterator iterator = tabmap.keySet().iterator(); iterator.hasNext();) {
                Name name = (Name) iterator.next();
                System.out.println(name.toString() + " - " + tabmap.get(name).toString());
            }
            //System.out.println("Tables : " + visitor.getCurrentTable());
            //获取操作方法名称,依赖于表名称
            System.out.println("Manipulation : " + visitor.getTables());
            //获取字段名称
            System.out.println("fields : " + visitor.getColumns());
        }
 
    }
 
}