详解java如何解析和生成sql

<dependency>
    <groupId>com.github.jsqlparser</groupId>
    <artifactId>jsqlparser</artifactId>
    <version>3.2</version>
</dependency>

package com.et;

import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.statement.select.Select;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.SelectItem;
import net.sf.jsqlparser.expression.Expression;

import java.util.List;

public class SqlParserExample {
    public static void main(String[] args) {
        // SQL query to be parsed
        String sql = "SELECT id, name FROM users WHERE age > 30";
        try {
            // Parse the SQL statement
            Statement statement = CCJSqlParserUtil.parse(sql);
            
            // Ensure the parsed statement is a SELECT statement
            if (statement instanceof Select) {
                Select selectStatement = (Select) statement;
                PlainSelect plainSelect = (PlainSelect) selectStatement.getSelectBody();

                // Get the selected columns
                List<SelectItem> selectItems = plainSelect.getSelectItems();
                System.out.println("Selected columns:");
                for (SelectItem item : selectItems) {
                    System.out.println(item);
                }

                // Get the WHERE condition
                Expression where = plainSelect.getWhere();
                System.out.println("WHERE condition:");
                if (where != null) {
                    System.out.println(where);
                } else {
                    System.out.println("No WHERE condition");
                }
            }
        } catch (Exception e) {
            e.printStackTrace(); // Print the stack trace in case of an exception
        }
    }
}

package com.et;

import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.schema.Table;
import net.sf.jsqlparser.statement.select.Select;
import net.sf.jsqlparser.statement.select.SelectBody;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.SelectItem;
import net.sf.jsqlparser.expression.LongValue;
import net.sf.jsqlparser.expression.BinaryExpression;
import net.sf.jsqlparser.expression.operators.relational.GreaterThan;
import net.sf.jsqlparser.statement.select.SelectExpressionItem; // Ensure SelectExpressionItem class is imported

import java.util.ArrayList;
import java.util.List;

public class SqlGeneratorExample {
    public static void main(String[] args) {
        // Create a Select object
        Select select = new Select();
        
        // Create a PlainSelect object
        PlainSelect plainSelect = new PlainSelect();
        
        // Set the selected columns
        List<SelectItem> selectItems = new ArrayList<>();
        selectItems.add(new SelectExpressionItem(new Column("id"))); // Use Column class for "id"
        selectItems.add(new SelectExpressionItem(new Column("name"))); // Use Column class for "name"
        plainSelect.setSelectItems(selectItems);
        
        // Set the table
        Table table = new Table("users");
        plainSelect.setFromItem(table);
        
        // Set the WHERE condition
        BinaryExpression whereCondition = new GreaterThan(); // Create a GreaterThan expression
        whereCondition.setLeftExpression(new Column("id")); // Set the left expression to the "id" column
        whereCondition.setRightExpression(new LongValue(10)); // Set the right expression to a LongValue of 10
        plainSelect.setWhere(whereCondition);
        
        // Set the PlainSelect as the SelectBody
        select.setSelectBody(plainSelect);
        
        // Generate the SQL statement
        String generatedSql = select.toString();
        System.out.println(generatedSql); // Print the generated SQL statement
    }
}