JSqlParser是一个与RDBMS无关的SQL语句解析器，支持多种方言，例如Oracle、SQL Server、MySQL、MariaDB、PostgreSQL、H2等。
JSqlParser将SQL语句转换为JAVA类的可遍历层次结构，还可以用于通过API从Java代码创建SQL语句。现在普遍使用的MyBatis-plus以及分页插件PageHelper都是借助JSqlParser实现SQL解析的。
JSqlParser源码主要包括以下几类对象：
对于下列SQL语句：
SELECT name, age, score FROM user WHERE id=1;
转换为Java对象层次结构为：
解析SQL代码实例：
public static void parseSQL() {
//Select语句样本
String sql1 = "select t1.f1,t1.f2,t2.id,count(*) from table1 t1 left join table2 t2 right join (select * from table3) t3 where t1.id='10' or (t1.id between 1 and 3 and t1.id>'12') group by t.f1 order by t.f1 desc,tf2 asc limit 1,20";
//Insert语句样本
String sql2 = "insert into table(f1,f2) values (1,2)";
//Create语句样本
String sql3 = "CREATE TABLE `sys_user` (n" +
" `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '编号',n" +
" `name` varchar(200) DEFAULT '' COMMENT '名称',n" +
" `age` tinyint(4) DEFAULT NULL COMMENT '年龄',n" +
" `create_by` varchar(64) DEFAULT '' COMMENT '创建者',n" +
" `create_time` datetime DEFAULT NULL COMMENT '创建时间',n" +
" `update_by` varchar(64) DEFAULT '' COMMENT '更新者',n" +
" `update_time` datetime DEFAULT NULL COMMENT '更新时间',n" +
" `remark` varchar(500) DEFAULT NULL COMMENT '备注',n" +
" PRIMARY KEY (`id`)n" +
") ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='用户表';";
try {
//处理Select语句
Select select = (Select) CCJSqlParserUtil.parse(sql1);
TablesNamesFinder tablesNamesFinder = new TablesNamesFinder();
List<String> tableList = tablesNamesFinder.getTableList(select);
// 获取到查询sql中的所有表名
System.out.println("表名:" + tableList);
//处理Insert语句
Insert insert = (Insert) CCJSqlParserUtil.parse(sql2);
System.out.println("插入的表" + insert.getTable());
System.out.println("插入的列" + insert.getColumns());
System.out.println("插入的值" + insert.getItemsList());
//处理Create Table语句
Statement statement = CCJSqlParserUtil.parse(sql3);
if (statement instanceof CreateTable) {
CreateTable createTable = ((CreateTable) statement);
Table table = createTable.getTable();
//通过columnDefinition进而可以获取列名、数据类型等
List<ColumnDefinition> columnDefinitions = createTable.getColumnDefinitions();
System.out.println(table);
System.out.println(columnDefinitions);
}
} catch (Exception e) {
e.printStackTrace();
}
}
输出如下：
表名:[table1, table2, table3]
插入的表table
插入的列[f1, f2]
插入的值(1, 2)
`sys_user`
[`id` bigint (20) NOT NULL AUTO_INCREMENT COMMENT '编号', `username` varchar (200) DEFAULT '' COMMENT '名称', `age` tinyint (4) DEFAULT NULL COMMENT '年龄', `create_by` varchar (64) DEFAULT '' COMMENT '创建者', `create_time` datetime DEFAULT NULL COMMENT '创建时间', `update_by` varchar (64) DEFAULT '' COMMENT '更新者', `update_time` datetime DEFAULT NULL COMMENT '更新时间', `remark` varchar (500) DEFAULT NULL COMMENT '备注']
/**
* 创建SQL查询语句
*
* @throws JSQLParserException
*/
public static void createSQL() throws JSQLParserException {
// 单表全量
Table table = new Table("sys_user");
//查询所有列
Select select = SelectUtils.buildSelectFromTable(table);
// SELECT * FROM sys_user
System.out.println(select);
// 指定列查询
Select buildSelectFromTableAndExpressions = SelectUtils.buildSelectFromTableAndExpressions(new Table("test"), new Column("col1"), new Column("col2"));
// SELECT col1, col2 FROM sys_user
System.out.println(buildSelectFromTableAndExpressions);
// WHERE =
EqualsTo equalsTo = new EqualsTo(); // 等于表达式
// 设置表达式左边值
equalsTo.setLeftExpression(new Column(table, "user_id"));
// 设置表达式右边值
equalsTo.setRightExpression(new StringValue("123456"));
// 转换为更细化的Select对象
PlAInSelect plainSelect = (PlainSelect) select.getSelectBody();
plainSelect.setWhere(equalsTo);
// SELECT * FROM sys_user WHERE sys_user.user_id = '123456'
System.out.println(plainSelect);
// WHERE != <>
NotEqualsTo notEqualsTo = new NotEqualsTo();
notEqualsTo.setLeftExpression(new Column(table, "user_id")); // 设置表达式左边值
notEqualsTo.setRightExpression(new StringValue("123456"));// 设置表达式右边值
PlainSelect plainSelectNot = (PlainSelect) select.getSelectBody();
plainSelectNot.setWhere(notEqualsTo);
System.out.println(plainSelectNot);// SELECT * FROM sys_user WHERE sys_user.user_id <> '123456'
// 其他运算符, 参考上面代码添加表达式即可
GreaterThan gt = new GreaterThan(); // ">"
GreaterThanEquals geq = new GreaterThanEquals(); // ">="
MinorThan mt = new MinorThan(); // "<"
MinorThanEquals leq = new MinorThanEquals();// "<="
IsNullExpression isNull = new IsNullExpression(); // "is null"
isNull.setNot(true);// "is not null"
LikeExpression nlike = new LikeExpression();
nlike.setNot(true); // "not like"
Between bt = new Between();
bt.setNot(true);// "not between"
// WHERE LIKE
LikeExpression likeExpression = new LikeExpression(); // 创建Like表达式对象
likeExpression.setLeftExpression(new Column("username")); // 表达式左边
likeExpression.setRightExpression(new StringValue("张%")); // 右边表达式
PlainSelect plainSelectLike = (PlainSelect) select.getSelectBody();
plainSelectLike.setWhere(likeExpression);
System.out.println(plainSelectLike); // SELECT * FROM sys_user WHERE username LIKE '张%'
// WHERE IN
Set<String> deptIds = Sets.newLinkedHashSet(); // 创建IN范围的元素集合
deptIds.add("0001");
deptIds.add("0002");
ItemsList itemsList = new ExpressionList(deptIds.stream().map(StringValue::new).collect(Collectors.toList())); // 把集合转变为JSQLParser需要的元素列表
InExpression inExpression = new InExpression(new Column("dept_id "), itemsList); // 创建IN表达式对象，传入列名及IN范围列表
PlainSelect plainSelectIn = (PlainSelect) select.getSelectBody();
plainSelectIn.setWhere(inExpression);
System.out.println(plainSelectIn); // SELECT * FROM sys_user WHERE dept_id IN ('0001', '0002')
// WHERE BETWEEN AND
Between between = new Between();
between.setBetweenExpressionStart(new LongValue(18)); // 设置起点值
between.setBetweenExpressionEnd(new LongValue(30)); // 设置终点值
between.setLeftExpression(new Column("age")); // 设置左边的表达式，一般为列
PlainSelect plainSelectBetween = (PlainSelect) select.getSelectBody();
plainSelectBetween.setWhere(between);
System.out.println(plainSelectBetween); // SELECT * FROM sys_user WHERE age BETWEEN 18 AND 30
// WHERE AND 多个条件结合,都需要成立
AndExpression andExpression = new AndExpression(); // AND 表达式
andExpression.setLeftExpression(equalsTo); // AND 左边表达式
andExpression.setRightExpression(between); // AND 右边表达式
PlainSelect plainSelectAnd = (PlainSelect) select.getSelectBody();
plainSelectAnd.setWhere(andExpression);
System.out.println(plainSelectAnd); // SELECT * FROM sys_user WHERE sys_user.user_id = '123456' AND age BETWEEN 18 AND 30
// WHERE OR 多个条件满足一个条件成立返回
OrExpression orExpression = new OrExpression();// OR 表达式
orExpression.setLeftExpression(equalsTo); // OR 左边表达式
orExpression.setRightExpression(between); // OR 右边表达式
PlainSelect plainSelectOr = (PlainSelect) select.getSelectBody();
plainSelectOr.setWhere(orExpression);
System.out.println(plainSelectOr); // SELECT * FROM sys_user WHERE sys_user.user_id = '123456' OR age BETWEEN 18 AND 30
// ORDER BY 排序
OrderByElement orderByElement = new OrderByElement(); // 创建排序对象
orderByElement.isAsc(); // 设置升序排列 从小到大
orderByElement.setExpression(new Column("col01")); // 设置排序字段
PlainSelect plainSelectOrderBy = (PlainSelect) select.getSelectBody();
plainSelectOrderBy.addOrderByElements(orderByElement);
// SELECT * FROM sys_user WHERE sys_user.user_id = '123456' OR age BETWEEN 18 AND 30 ORDER BY col01
System.out.println(plainSelectOrderBy);
}
输出如下：
SELECT * FROM sys_user
SELECT col1, col2 FROM sys_user
SELECT * FROM sys_user WHERE sys_user.user_id = '123456'
SELECT * FROM sys_user WHERE sys_user.user_id <> '123456'
SELECT * FROM sys_user WHERE username LIKE '张%'
SELECT * FROM sys_user WHERE dept_id IN ('0001', '0002')
SELECT * FROM sys_user WHERE age BETWEEN 18 AND 30
SELECT * FROM sys_user WHERE sys_user.user_id = '123456' AND age BETWEEN 18 AND 30
SELECT * FROM sys_user WHERE sys_user.user_id = '123456' OR age BETWEEN 18 AND 30
SELECT * FROM sys_user WHERE sys_user.user_id = '123456' OR age BETWEEN 18 AND 30 ORDER BY col01
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