MybatisPlusInterceptor实现sql拦截器(超详细)

MyBatis-Plus 提供了插件接口 MybatisPlusInterceptor，用于拦截 MyBatis 的相关操作，例如 SQL 查询、插入、更新、删除等。

以下是一个简单的 MyBatisPlusInterceptor 实现示例，用于拦截并修改 SQL 语句：

import com.baomidou.mybatisplus.core.parser.ISqlParser;
import com.baomidou.mybatisplus.extension.handlers.AbstractSqlParserHandler;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.operators.conditional.AndExpression;
import net.sf.jsqlparser.expression.operators.relational.EqualsTo;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.PlainSelect;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.plugin.*;
 
import java.sql.Connection;
import java.util.Properties;
 
@Intercepts({
    @Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})
})
public class MyInterceptor extends MybatisPlusInterceptor {
 
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        // 获取StatementHandler，实际处理者
        StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
        // 获得SQL
        BoundSql boundSql = statementHandler.getBoundSql();
        String sql = boundSql.getSql();
        System.out.println("Original SQL: " + sql);
 
        // 修改SQL
        String modifiedSql = modifySql(sql);
        System.out.println("Modified SQL: " + modifiedSql);
 
        // 反射修改SQL
        Field sqlField = boundSql.getClass().getDeclaredField("sql");
        sqlField.setAccessible(true);
        sqlField.set(boundSql, modifiedSql);
 
        // 继续执行
        return invocation.proceed();
    }
 
    private String modifySql(String originalSql) {
        try {
            // 解析SQL
            PlainSelect plainSelect = (PlainSelect) CCJSqlParserUtil.parse(originalSql);
            // 添加额外条件
            EqualsTo equalsTo = new EqualsTo();
            equalsTo.setLeftExpression(new Column("字段名"));
            equalsTo.setRightExpression(new StringValue("条件值"));
            AndExpression andExpression = new AndExpression(equalsTo);
            plainSelect.setWhere(andExpression);
            // 生成修改后的SQL
            return plainSelect.toString()