Jsqlparser简单学习

学习链接

java设计模式：访问者模式

github使用示例参考

测试 JSqlParser使用示例

JSqlParse（一）基本增删改查语句build
JSqlParse（二）带where的查询语句build

JSqlParser专栏系列教程

jsqlparser:基于抽象语法树(AST)遍历SQL语句的语法元素

Sql解析转换之JSqlParse完整介绍

JSqlParser系列之二代码结构（原）

JSQLPARSER解析SQL知识入门

jsqlparser基本使用

模块

访问者模式

访问者模式理解：

1. 有固定结构的数据封装类，结构基本不会发生变化。它们都有1个接收访问者的方法。

2. 访问者针对每1个具体的结构封装类都有1个具体的访问方法。

3. 在具体的结构封装类接收访问者的方法中，可直接调用访问者针对当前结构类的方法。

4. 如果封装类结构不是固定的，那么不能使用这种模式

parser模块

statement模块

Expression模块

deparser模块

测试

TestDrop

先创建java对象（结构），使用deparser将java对象转为（得到）sql字符串

import net.sf.jsqlparser.schema.Table;
import net.sf.jsqlparser.statement.drop.Drop;
import net.sf.jsqlparser.util.deparser.DropDeParser;
import org.junit.Test;public class TestDrop {@Testpublic void test_drop() {// 创建DropDrop drop = new Drop();// 创建TableTable table = new Table();table.setName("sys_user");// 设置dropdrop.setName(table);drop.setType("table");drop.setIfExists(true);// 最终的sqlStringBuilder stringBuilder = new StringBuilder();// 使用DropDeParser来将java对象(封装了sql信息)转为具体的sql语句// （这里的代码是参照StatementDeParser#visit(Drop)）DropDeParser dropDeParser = new DropDeParser(stringBuilder);dropDeParser.deParse(drop);// 获取最终的目标sqlString sql = dropDeParser.getBuffer().toString();// DROP table IF EXISTS sys_userSystem.out.println(sql);}}

TestSelect

给原来的sql语句添加查询条件：age > 18 and dept_id in (1,2,3)

package com.zzhua;import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.LongValue;
import net.sf.jsqlparser.expression.operators.conditional.AndExpression;
import net.sf.jsqlparser.expression.operators.relational.EqualsTo;
import net.sf.jsqlparser.expression.operators.relational.ExpressionList;
import net.sf.jsqlparser.expression.operators.relational.InExpression;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.Select;
import net.sf.jsqlparser.statement.select.SelectBody;
import net.sf.jsqlparser.util.deparser.ExpressionDeParser;
import net.sf.jsqlparser.util.deparser.SelectDeParser;
import net.sf.jsqlparser.util.deparser.StatementDeParser;
import org.junit.Test;import java.util.ArrayList;public class TestSelect {@Testpublic void test_select() throws JSQLParserException {Statement statement = CCJSqlParserUtil.parse("select id,nick_name from sys_user where id > 10");if (statement instanceof Select) {System.out.println("select语句");Select select = (Select) statement;StringBuilder buffer = new StringBuilder();// （这里的代码是参照 StatementDeParser#visit(Select)）// SelectParser实现了SelectVisitor接口, 能够访问PlainSelect、SetOperationList、WithItemSelectDeParser selectDeParser = new SelectDeParser();selectDeParser.setBuffer(buffer);ExpressionDeParser expressionDeParser = new ExpressionDeParser(selectDeParser, buffer);selectDeParser.setExpressionVisitor(expressionDeParser);// SelectBody接收selectParser的访问(访问的结果会添加到buffer中)select.getSelectBody().accept(selectDeParser);// 输出原始的sql: SELECT id, nick_name FROM sys_user WHERE id > 10System.out.println(buffer);SelectBody selectBody = select.getSelectBody();if (selectBody instanceof PlainSelect) {// 原来的selectBodyPlainSelect plainSelect = (PlainSelect) select.getSelectBody();// age = 18EqualsTo equalsTo = new EqualsTo();Column ageColumn = new Column("age");equalsTo.setLeftExpression(ageColumn);equalsTo.setRightExpression(new LongValue(18));// 在原来的where条件中拼接上刚刚创建的条件 age=18, 并使用And连接起来AndExpression andExpression1 = new AndExpression(plainSelect.getWhere(), equalsTo);// dept_id in (1,2,3)InExpression inExpression = new InExpression();inExpression.setLeftExpression(new Column("dept_id"));ExpressionList expressionList = new ExpressionList(new ArrayList<>());expressionList.getExpressions().add(new LongValue(1));expressionList.getExpressions().add(new LongValue(2));expressionList.getExpressions().add(new LongValue(3));inExpression.setRightItemsList(expressionList);AndExpression andExpression2 = new AndExpression(andExpression1, inExpression);// 替换掉原来的where条件plainSelect.setWhere(andExpression2);// 直接参考StatementDeParserStatementDeParser statementDeParser = new StatementDeParser(new StringBuilder());Select newSelect = new Select();newSelect.setSelectBody(plainSelect);statementDeParser.visit(newSelect);// 输出sql: SELECT id, nick_name FROM sys_user WHERE id > 10 AND age = 18 AND dept_id IN (1, 2, 3)System.out.println(statementDeParser.getBuffer());}}}}

TestSelectVisitor

@Slf4j
public class TestSelectVisitor {public static void main(String[] args) throws Exception {String sqlStr ="SELECT\n" +"                su.dept_id `deptId`,\n" +"                su.user_id,\n" +"                sr.role_id,\n" +"                su.user_name,\n" +"                sd.dept_name,\n" +"                sr.role_name\n" +"            FROM\n" +"                sys_user AS su\n" +"                JOIN sys_dept sd ON su.dept_id = sd.dept_id\n" +"                JOIN sys_user_role sur ON sur.user_id = su.user_id\n" +"                JOIN sys_role sr ON sur.role_id = sr.role_id\n" +"            WHERE\n" +"                sd.dept_name = '研发部门'\n" +"                AND su.user_name = 'admin'\n" +"                AND su.dept_id = 103\n" +"                OR sr.role_name = '超级管理员'\n" +"                ORDER BY\n" +"                sd.create_time DESC";Select querySql = (Select)CCJSqlParserUtil.parse(sqlStr);querySql.getSelectBody().accept(new SelectVisitorAdapter() {@Overridepublic void visit(PlainSelect plainSelect) {log.info("--------------查询列名----------------------------------------");plainSelect.getSelectItems().stream().forEach(selectItem -> {selectItem.accept(new SelectItemVisitorAdapter() {@Overridepublic void visit(SelectExpressionItem selectExpressionItem) {log.info(selectExpressionItem.getExpression().toString());if (selectExpressionItem.getAlias()!=null) {log.info("列别名 {}",selectExpressionItem.getAlias().getName());}}});});log.info("--------------From Table Info----------------------------------------");log.info(plainSelect.getFromItem().toString());if (plainSelect.getFromItem().getAlias()!=null) {log.info("表别名"+plainSelect.getFromItem().getAlias().getName());}log.info("--------------Join Table Info----------------------------------------");plainSelect.getJoins().stream().forEach(join -> {log.info(join.toString());log.info("关联表：{} ",join.getRightItem());if (join.getRightItem().getAlias()!=null) {log.info("关联表别名：{}",join.getRightItem().getAlias().getName());}log.info("关联条件：{}",join.getOnExpression().toString());});log.info("--------------Where  Info----------------------------------------");plainSelect.getWhere().accept(new ExpressionVisitorAdapter() {@Overridepublic void visitBinaryExpression(BinaryExpression expr) {log.info("表达式：{}",expr.toString());log.info("表达式左侧：{}",expr.getLeftExpression().toString());log.info("表达式右侧：{}",expr.getRightExpression().toString());}});log.info("--------------增加查询条件----------------------------------------");try {plainSelect.setWhere(new AndExpression(CCJSqlParserUtil.parseCondExpression("1=1"),plainSelect.getWhere()));} catch (JSQLParserException e) {throw new RuntimeException(e);}}});log.info("语句：{}",querySql.toString());}
}/*
--------------查询列名----------------------------------------
su.dept_id
列别名 `deptId`
su.user_id
sr.role_id
su.user_name
sd.dept_name
sr.role_name
--------------From Table Info----------------------------------------
sys_user AS su
表别名su
--------------Join Table Info----------------------------------------
JOIN sys_dept sd ON su.dept_id = sd.dept_id
关联表：sys_dept sd 
关联表别名：sd
关联条件：su.dept_id = sd.dept_id
JOIN sys_user_role sur ON sur.user_id = su.user_id
关联表：sys_user_role sur 
关联表别名：sur
关联条件：sur.user_id = su.user_id
JOIN sys_role sr ON sur.role_id = sr.role_id
关联表：sys_role sr 
关联表别名：sr
关联条件：sur.role_id = sr.role_id
--------------Where  Info----------------------------------------
表达式：sd.dept_name = '研发部门' AND su.user_name = 'admin' AND su.dept_id = 103 OR sr.role_name = '超级管理员'
表达式左侧：sd.dept_name = '研发部门' AND su.user_name = 'admin' AND su.dept_id = 103
表达式右侧：sr.role_name = '超级管理员'
--------------增加查询条件----------------------------------------
语句：SELECT su.dept_id `deptId`, su.user_id, sr.role_id, su.user_name, sd.dept_name, sr.role_name FROM sys_user AS su JOIN sys_dept sd ON su.dept_id = sd.dept_id JOIN sys_user_role sur ON sur.user_id = su.user_id JOIN sys_role sr ON sur.role_id = sr.role_id WHERE 1 = 1 AND sd.dept_name = '研发部门' AND su.user_name = 'admin' AND su.dept_id = 103 OR sr.role_name = '超级管理员' ORDER BY sd.create_time DESC
*/