JSqlparser github地址
JSqlParser is a SQL statement parser. It translates SQLs in a traversable hierarchy of Java classes. JSqlParser is not limited to one database but provides support for a lot of specials of Oracle, SqlServer, MySQL, PostgreSQL … To name some, it has support for Oracles join syntax using (+), PostgreSQLs cast syntax using ::, relational operators like != and so on.
JSqlParser 是SQL语句分析的插件，他使用Java语言去解析SQL。
sqlparser提供很多的数据库语法解析支持其中支持很多oracle的特殊语法。
可以结合mybatis的拦截修改SQL来实现多租户、SQL拼接甚至联表的功能。
可以参考我之前写的MyBatis通过拦截修改SQL
<repositories>
<repository>
<id>jsqlparser-snapshots</id>
<snapshots>
<enabled>true</enabled>
</snapshots>
<url>https://oss.sonatype.org/content/groups/public/</url>
</repository>
</repositories><dependency> <groupId>com.github.jsqlparser</groupId> <artifactId>jsqlparser</artifactId> <version>4.4</version> </dependency>
public class TestSqlparser {
public static void main(String[] args) throws JSQLParserException {
// 根据sql创建select
Select stmt = (Select) CCJSqlParserUtil.parse("SELECT col1 AS a, col2 AS b, col3 AS c FROM table T WHERE col1 = 10 AND col2 = 20 AND col3 = 30");
Map<String, Expression> map = new HashMap<>();
Map<String, String> mapTable = new HashMap<>();
((PlainSelect) stmt.getSelectBody()).getFromItem().accept(new FromItemVisitorAdapter() {
@Override
public void visit(Table table) {
// 获取别名 => 表名
mapTable.put(table.getAlias().getName(), table.getName());
}
});
((PlainSelect) stmt.getSelectBody()).getWhere().accept(new ExpressionVisitorAdapter() {
@Override
public void visit(AndExpression expr) {
// 获取where表达式
System.out.println(expr);
}
});
for (SelectItem selectItem : ((PlainSelect)stmt.getSelectBody()).getSelectItems()) {
selectItem.accept(new SelectItemVisitorAdapter() {
@Override
public void visit(SelectExpressionItem item) {
// 获取字段别名 => 字段名
map.put(item.getAlias().getName(), item.getExpression());
}
});
}
System.out.println("map " + map);
System.out.println("mapTables" + mapTable);
}
}
创建Select（非SQL String 创建）
@Test
public void testCreateSelect1 () throws JSQLParserException {
Select select1 = SelectUtils.buildSelectFromTable(new Table("mytable"));
Select select2 = SelectUtils.buildSelectFromTableAndExpressions(new Table("mytable"), new Column("a"), new Column("b"));
Select select3 = SelectUtils.buildSelectFromTableAndExpressions(new Table("mytable"), "a+b", "test");
System.out.println(select1.toString());
System.out.println(select2.toString());
System.out.println(select3.toString());
}
@Test
public void testCreateSelect2() throws JSQLParserException {
Insert insert = (Insert) CCJSqlParserUtil.parse("insert into mytable (col1) values (1)");
System.out.println(insert.toString());
//adding a column
insert.getColumns().add(new Column("col2"));
//adding a value using a visitor
insert.getItemsList().accept(new ItemsListVisitor() {
public void visit(SubSelect subSelect) {
throw new UnsupportedOperationException("Not supported yet.");
}
public void visit(ExpressionList expressionList) {
expressionList.getExpressions().add(new LongValue(5));
}
@Override
public void visit(NamedExpressionList namedExpressionList) {
}
public void visit(MultiExpressionList multiExprList) {
throw new UnsupportedOperationException("Not supported yet.");
}
});
System.out.println(insert.toString());
//adding another column
insert.getColumns().add(new Column("col3"));
//adding another value (the easy way)
((ExpressionList) insert.getItemsList()).getExpressions().add(new LongValue(10));
System.out.println(insert.toString());
}
import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.LongValue;
import net.sf.jsqlparser.expression.StringValue;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.util.deparser.ExpressionDeParser;
import net.sf.jsqlparser.util.deparser.SelectDeParser;
import net.sf.jsqlparser.util.deparser.StatementDeParser;
public class ReplaceColumnValues {
static class ReplaceColumnAndLongValues extends ExpressionDeParser {
@Override
public void visit(StringValue stringValue) {
this.getBuffer().append("?");
}
@Override
public void visit(LongValue longValue) {
this.getBuffer().append("?");
}
}
public static String cleanStatement(String sql) throws JSQLParserException {
StringBuilder buffer = new StringBuilder();
ExpressionDeParser expr = new ReplaceColumnAndLongValues();
SelectDeParser selectDeparser = new SelectDeParser(expr, buffer);
expr.setSelectVisitor(selectDeparser);
expr.setBuffer(buffer);
StatementDeParser stmtDeparser = new StatementDeParser(expr, selectDeparser, buffer);
Statement stmt = CCJSqlParserUtil.parse(sql);
stmt.accept(stmtDeparser);
return stmtDeparser.getBuffer().toString();
}
public static void main(String[] args) throws JSQLParserException {
System.out.println(cleanStatement("SELECT 'abc', 5 FROM mytable WHERE col='test'"));
System.out.println(cleanStatement("UPDATE table1 A SET A.columna = 'XXX' WHERE A.cod_table = 'YYY'"));
System.out.println(cleanStatement("INSERT INTO example (num, name, address, tel) VALUES (1, 'name', 'test ', '1234-1234')"));
System.out.println(cleanStatement("DELETE FROM table1 where col=5 and col2=4"));
}
}
输出：
SELECT ?, ? FROM mytable WHERE col = ?
UPDATE table1 A SET A.columna = ? WHERE A.cod_table = ?
INSERT INTO example (num, name, address, tel) VALUES (?, ?, ?, ?)
DELETE FROM table1 WHERE col = ? AND col2 = ?
替换条件字段col_1到col1
@Test
public void replace () throws JSQLParserException {
Select stmt = (Select) CCJSqlParserUtil.parse("SELECT col1 AS a, col2 AS b, col3 AS c FROM table WHERE col_1 = 10 AND col_2 = 20 AND col_3 = 30");
System.out.println("before " + stmt.toString());
((PlainSelect)stmt.getSelectBody()).getWhere().accept(new ExpressionVisitorAdapter() {
@Override
public void visit(Column column) {
column.setColumnName(column.getColumnName().replace("_", ""));
}
});
System.out.println("after " + stmt.toString());
}
Statement stmt = CCJSqlParserUtil.parse("SELECT * FROM tab1");
Statements stmt = CCJSqlParserUtil.parseStatements("SELECT * FROM tab1; SELECT * FROM tab2");
Expression expr = CCJSqlParserUtil.parseExpression("a*(5+mycolumn)");可以直接将String SQL片段解析成Expression再将expr插入到SQL语句中。
获取所有tableNames
Statement statement = CCJSqlParserUtil.parse("SELECT * FROM MY_TABLE1");
Select selectStatement = (Select) statement;
TablesNamesFinder tablesNamesFinder = new TablesNamesFinder();
List<String> tableList = tablesNamesFinder.getTableList(selectStatement);自动生成别名
Select select = (Select) CCJSqlParserUtil.parse("select a,b,c from test");
final AddAliasesVisitor instance = new AddAliasesVisitor();
select.getSelectBody().accept(instance);结果：
SELECT a AS A1, b AS A2, c AS A3 FROM test
SQL函数
/**
* SQL 函数
* SELECT function(列) FROM 表
*/
@Test
public void testFun() throws JSQLParserException {
Table t1 = new Table("tab1").withAlias(new Alias("t1").withUseAs(true)); // 表1
PlainSelect plainSelect = new PlainSelect();
plainSelect.setFromItem(t1); // 设置FROM t1= > SELECT FROM tab1 AS t1
List<SelectItem> selectItemList = new ArrayList<>(); // 查询元素集合
SelectExpressionItem selectExpressionItem001 = new SelectExpressionItem(); // 元素1表达式
selectExpressionItem001.setExpression(new Column(t1,"col001"));
SelectExpressionItem selectExpressionItem002 = new SelectExpressionItem(); // 元素2表达式
selectExpressionItem002.setExpression(new Column(t1,"col002"));
selectItemList.add(0, selectExpressionItem001); // 添加入队
selectItemList.add(1, selectExpressionItem002); // 添加入队
// COUNT
SelectExpressionItem selectExpressionItemCount = new SelectExpressionItem(); // 创建函数元素表达式
selectExpressionItemCount.setAlias(new Alias("count")); // 设置别名
Function function = new Function(); // 创建函数对象 Function extends ASTNodeAccessImpl implements Expression
function.setName("COUNT"); // 设置函数名
ExpressionList expressionListCount = new ExpressionList(); // 创建参数表达式
expressionListCount.setExpressions(Collections.singletonList(new Column(t1, "id")));
function.setParameters(expressionListCount); // 设置参数
selectExpressionItemCount.setExpression(function);
selectItemList.add(2,selectExpressionItemCount);
plainSelect.setSelectItems(selectItemList); // 添加查询元素集合入select对象
System.err.println(plainSelect); // SELECT t1.col001, t1.col002, COUNT(t1.id) AS count FROM tab1 AS t1
}单表where条件拼装
/**
* 单表SQL查询
*
* @throws JSQLParserException
*/
@Test
public void testSelectOneTable() throws JSQLParserException {
// 单表全量
Table table = new Table("test");
Select select = SelectUtils.buildSelectFromTable(table);
System.err.println(select); // SELECT * FROM test
// 指定列查询
Select buildSelectFromTableAndExpressions = SelectUtils.buildSelectFromTableAndExpressions(new Table("test"), new Column("col1"), new Column("col2"));
System.err.println(buildSelectFromTableAndExpressions); // SELECT col1, col2 FROM test
// WHERE =
EqualsTo equalsTo = new EqualsTo(); // 等于表达式
equalsTo.setLeftExpression(new Column(table, "user_id")); // 设置表达式左边值
equalsTo.setRightExpression(new StringValue("123456"));// 设置表达式右边值
PlainSelect plainSelect = (PlainSelect) select.getSelectBody(); // 转换为更细化的Select对象
plainSelect.setWhere(equalsTo);
System.err.println(plainSelect);// SELECT * FROM test WHERE test.user_id = '123456'
// 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.err.println(plainSelectNot);// SELECT * FROM test WHERE test.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.err.println(plainSelectLike); // SELECT * FROM test 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.err.println(plainSelectIn); // SELECT * FROM test 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.err.println(plainSelectBetween); // SELECT * FROM test 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.err.println(plainSelectAnd); // SELECT * FROM test WHERE test.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.err.println(plainSelectOr); // SELECT * FROM test WHERE test.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);
System.err.println(plainSelectOrderBy); // SELECT * FROM test WHERE test.user_id = '123456' OR age BETWEEN 18 AND 30 ORDER BY col01
}JOIN 拼装
/**
* 多表SQL查询
* JOIN / INNER JOIN: 如果表中有至少一个匹配，则返回行
* LEFT JOIN: 即使右表中没有匹配，也从左表返回所有的行
* RIGHT JOIN: 即使左表中没有匹配，也从右表返回所有的行
* FULL JOIN: 只要其中一个表中存在匹配，就返回行
*/
@Test
public void testSelectManyTable() {
Table t1 = new Table("tab1").withAlias(new Alias("t1").withUseAs(true)); // 表1
Table t2 = new Table("tab2").withAlias(new Alias("t2", false)); // 表2
PlainSelect plainSelect = new PlainSelect().addSelectItems(new AllColumns()).withFromItem(t1); // SELECT * FROM tab1 AS t1
// JOIN ON 如果表中有至少一个匹配，则返回行
Join join = new Join(); // 创建Join对象
join.withRightItem(t2); // 添加Join的表 JOIN t2 =>JOIN tab2 t2
EqualsTo equalsTo = new EqualsTo(); // 添加 = 条件表达式 t1.user_id = t2.user_id
equalsTo.setLeftExpression(new Column(t1, "user_id "));
equalsTo.setRightExpression(new Column(t2, "user_id "));
join.withOnExpression(equalsTo);// 添加ON
plainSelect.addJoins(join);
System.err.println(plainSelect); // SELECT * FROM tab1 AS t1 JOIN tab2 t2 ON t1.user_id = t2.user_id
// 设置join参数可实现其他类型join
// join.setLeft(true); LEFT JOIN
// join.setRight(true); RIGHT JOIN
// join.setFull(true); FULL JOIN
// join.setInner(true);
}String sql = "DROP INDEX IF EXISTS idx_tab2_id;";
// validate statement if it's valid for all given databases.
Validation validation = new Validation(Arrays.asList(DatabaseType.SQLSERVER, DatabaseType.MARIADB,
DatabaseType.POSTGRESQL, DatabaseType.H2), sql);
List<ValidationError> errors = validation.validate();
// validate against pre-defined FeaturesAllowed.DML set
String sql = "CREATE TABLE tab1 (id NUMERIC(10), val VARCHAR(30))";
Validation validation = new Validation(Arrays.asList(FeaturesAllowed.DML), sql);
List<ValidationError> errors = validation.validate();
// only DML is allowed, got error for using a DDL statement
log.error (errors);Validates metadata such as names of tables, views, columns for their existence or non-existence
java.sql.Connection connection = ...;
String sql = "ALTER TABLE mytable ADD price numeric(10,5) not null";
Validation validation = new Validation(Arrays.asList(new JdbcDatabaseMetaDataCapability(connection,
// NamesLookup: Databases handle names differently
NamesLookup.UPPERCASE)), sql);
List<ValidationError> errors = validation.validate();
// do something else with the parsed statements
Statements statements = validation.getParsedStatements();
// check for validation-errors
if (!errors.isEmpty()) {
...
}我们可以借助JSqlparser来解析SQL并且动态拼接生成SQL，在Mybatis-plus中的租户其实也是类似这样实现的。
甚至有兴趣的同学可以自己做一个SQL拼装器，将前台筛选的条件转换为SQL进行查询。所有的查询字段、条件、联表等等都做成动态拼装。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
