SingleColumnResultSqlConditionBuilder

import java.util.List;
import com.alibaba.druid.sql.SQLUtils;
import com.alibaba.druid.sql.ast.SQLExpr;
import com.alibaba.druid.sql.ast.SQLStatement;
import com.alibaba.druid.sql.ast.expr.SQLBinaryOpExpr;
import com.alibaba.druid.sql.ast.expr.SQLBinaryOperator;
import com.alibaba.druid.sql.ast.expr.SQLCharExpr;
import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
import com.alibaba.druid.sql.ast.statement.SQLSelect;
import com.alibaba.druid.sql.ast.statement.SQLSelectItem;
import com.alibaba.druid.sql.ast.statement.SQLSelectQuery;
import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectQueryBlock;
import com.alibaba.druid.sql.dialect.oracle.visitor.OracleOutputVisitor;
import com.alibaba.druid.util.JdbcUtils;

public class SingleColumnResultSqlConditionBuilder {

    private String sql;
    private String conditionValue;

    public SingleColumnResultSqlConditionBuilder(String sql, String conditionValue) {
        super();
        this.sql = sql;
        this.conditionValue = conditionValue;
    }

    public String build() {
        List stmtList = SQLUtils.parseStatements(this.sql, JdbcUtils.ORACLE);
        if (stmtList.size() > 1) {
            throw new IllegalArgumentException("sql:" + this.sql + ",只能是一条语句语句");
        }
        SQLStatement singleOneStme = stmtList.get(0);
        if (!(singleOneStme instanceof SQLSelectStatement)) {
            throw new IllegalArgumentException("sql:" + this.sql + ",只能查询语句");
        }

        SQLSelectStatement sqlSelectStatement = (SQLSelectStatement) singleOneStme;
        SQLSelect sqlSelect = sqlSelectStatement.getSelect();
        SQLSelectQuery sqlSelectQuery = sqlSelect.getQuery();
        
        //是查询语句块
        if (sqlSelectQuery instanceof OracleSelectQueryBlock) {
            OracleSelectQueryBlock oracleSelectQueryBlock = (OracleSelectQueryBlock)sqlSelectQuery;
            List sqlSelectItems = oracleSelectQueryBlock.getSelectList();
            if (sqlSelectItems.size() > 1) {
                throw new IllegalArgumentException("sql:" + this.sql + ",只能返回单列");
            }
            SQLSelectItem sqlSelectItem = sqlSelectItems.get(0);
            SQLExpr sqlExpr = sqlSelectItem.getExpr();
            if (!(sqlExpr instanceof SQLIdentifierExpr)) {
                throw new IllegalArgumentException("sql:" + this.sql + ",返回的单列只能是标识符");
            }
            SQLIdentifierExpr sqlIdentifierExpr = (SQLIdentifierExpr) sqlExpr;
            String column = sqlIdentifierExpr.getName();

            // 构建额外的where条件
            SQLExpr oldWhereSqlExpr = oracleSelectQueryBlock.getWhere();
            
            SQLExpr left = new SQLIdentifierExpr(column);
            SQLExpr right = new SQLCharExpr(conditionValue);
            SQLBinaryOpExpr condition = new SQLBinaryOpExpr(left, SQLBinaryOperator.Equality, right);

            // 追加where条件
            if (oldWhereSqlExpr != null) {
                SQLExpr newWhereSqlExpr = new SQLBinaryOpExpr(oldWhereSqlExpr, SQLBinaryOperator.BooleanAnd, condition);
                oracleSelectQueryBlock.setWhere(newWhereSqlExpr);
            } else {

                oracleSelectQueryBlock.setWhere(condition);
            }
        }
        // 追加结果到buffer中
        StringBuffer resultSqlBuffer = new StringBuffer();
        
        OracleOutputVisitor oracleOutputVisitor = new OracleOutputVisitor(resultSqlBuffer);
        oracleOutputVisitor.setPrettyFormat(false);
        singleOneStme.accept(oracleOutputVisitor);

        String resultsql = resultSqlBuffer.toString();
        return resultsql;
    }
}

 

转载于:https://www.cnblogs.com/weiguangyue/p/9997147.html