文章目录
学习链接
JSqlParse（一）基本增删改查语句build
JSqlParse（二）带where的查询语句build
jsqlparser:基于抽象语法树(AST)遍历SQL语句的语法元素
模块
访问者模式
访问者模式理解：
-
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。
-
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。
-
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。
-
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
java
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 {
@Test
public void test_drop() {
// 创建Drop
Drop drop = new Drop();
// 创建Table
Table table = new Table();
table.setName("sys_user");
// 设置drop
drop.setName(table);
drop.setType("table");
drop.setIfExists(true);
// 最终的sql
StringBuilder 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sql
String sql = dropDeParser.getBuffer().toString();
// DROP table IF EXISTS sys_user
System.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)
java
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 {
@Test
public 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、WithItem
SelectDeParser 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 > 10
System.out.println(buffer);
SelectBody selectBody = select.getSelectBody();
if (selectBody instanceof PlainSelect) {
// 原来的selectBody
PlainSelect plainSelect = (PlainSelect) select.getSelectBody();
// age = 18
EqualsTo 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StatementDeParser
StatementDeParser 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
java
@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() {
@Override
public void visit(PlainSelect plainSelect) {
log.info("--------------查询列名----------------------------------------");
plainSelect.getSelectItems().stream().forEach(selectItem -> {
selectItem.accept(new SelectItemVisitorAdapter() {
@Override
public 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() {
@Override
public 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
*/