SQL解析利器JSqlParser

2023-04-21 今日头条 Esgoon

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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：

expression：SQL构建相关类，比如Function、EqualsTo、AndExpression、InExpression等表达式用于构建SQL。
parser：SQL解析相关类，比如CCJSqlParserUtil、CCJSqlParserManager、抽象语法树对象等。
schema：主要存放数据库schema相关的类，比如Database、Table、Column等。
statement：封装了数据库操作对象，create、insert、delete、select、drop、alter、truncate等。
util：各种工具类、不同DB版本、SQL标准等处理类，如SelectUtils、DatabaseType等。

解析SQL

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

/**
 * 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