Java JSqlParser解析,修改和生成SQL语句的实用技巧

在Java中使用 JSqlParser 可以高效地解析、修改和生成SQL语句。以下是实用技巧和操作示例，涵盖核心功能和常见场景：

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1. 添加依赖

确保项目中引入 JSqlParser 的依赖（以Maven为例）：

<dependency>
    <groupId>com.github.jsqlparser</groupId>
    <artifactId>jsqlparser</artifactId>
    <version>4.9</version> <!-- 根据需要选择最新版本 -->
</dependency>
<dependency>
    <groupId>com.github.jsqlparser</groupId>
    <artifactId>jsqlparser</artifactId>
    <version>4.9</version> <!-- 根据需要选择最新版本 -->
</dependency>
<dependency>
    <groupId>com.github.jsqlparser</groupId>
    <artifactId>jsqlparser</artifactId>
    <version>4.9</version> <!-- 根据需要选择最新版本 -->
</dependency>

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2. 解析SQL语句

通过 CCJSqlParserUtil.parse() 方法将SQL字符串解析为抽象语法树（AST）。

示例：解析SELECT语句

import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.Select;
public class ParseExample {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            System.out.println("解析成功: " + select);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.Select;

public class ParseExample {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            System.out.println("解析成功: " + select);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.Select;

public class ParseExample {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            System.out.println("解析成功: " + select);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

解析结果

• 返回 Select 对象，包含查询的表名、字段、条件等结构化信息。
• 支持解析 INSERT、UPDATE、DELETE 等其他SQL类型。

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3. 修改SQL语句

通过操作AST节点动态修改SQL，例如添加条件、更改字段或表名。

示例：添加WHERE条件

import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.*;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;
public class ModifySQL {
    public static void main(String[] args) {
        try {
            String sql = "SELECT * FROM orders WHERE status = 'completed'";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();
            // 创建新条件
            Expression newCondition = new EqualsTo(
                new Column("amount"),
                new LongValue(100)
            );
            // 合并条件（AND）
            if (plainSelect.getWhere() != null) {
                AndExpression andExpression = new AndExpression(plainSelect.getWhere(), newCondition);
                plainSelect.setWhere(andExpression);
            } else {
                plainSelect.setWhere(newCondition);
            }
            System.out.println("修改后的SQL: " + select);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.*;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;

public class ModifySQL {
    public static void main(String[] args) {
        try {
            String sql = "SELECT * FROM orders WHERE status = 'completed'";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();

            // 创建新条件
            Expression newCondition = new EqualsTo(
                new Column("amount"),
                new LongValue(100)
            );

            // 合并条件（AND）
            if (plainSelect.getWhere() != null) {
                AndExpression andExpression = new AndExpression(plainSelect.getWhere(), newCondition);
                plainSelect.setWhere(andExpression);
            } else {
                plainSelect.setWhere(newCondition);
            }

            System.out.println("修改后的SQL: " + select);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.expression.*;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;

public class ModifySQL {
    public static void main(String[] args) {
        try {
            String sql = "SELECT * FROM orders WHERE status = 'completed'";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();

            // 创建新条件
            Expression newCondition = new EqualsTo(
                new Column("amount"),
                new LongValue(100)
            );

            // 合并条件（AND）
            if (plainSelect.getWhere() != null) {
                AndExpression andExpression = new AndExpression(plainSelect.getWhere(), newCondition);
                plainSelect.setWhere(andExpression);
            } else {
                plainSelect.setWhere(newCondition);
            }

            System.out.println("修改后的SQL: " + select);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}

结果

SELECT * FROM orders WHERE status = 'completed' AND amount = 100
SELECT * FROM orders WHERE status = 'completed' AND amount = 100
SELECT * FROM orders WHERE status = 'completed' AND amount = 100

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4. 生成SQL语句

通过构建AST节点生成SQL，适用于动态SQL生成场景。

示例：生成SELECT语句

import net.sf.jsqlparser.statement.select.*;
public class GenerateSQL {
    public static void main(String[] args) {
        Select select = new Select();
        PlainSelect plainSelect = new PlainSelect();
        // 设置SELECT字段
        plainSelect.addSelectItems(
            new SelectExpressionItem(new Column("id")),
            new SelectExpressionItem(new Column("name"))
        );
        // 设置FROM表
        plainSelect.setFromItem(new Table("users"));
        // 设置WHERE条件
        plainSelect.setWhere(new EqualsTo(new Column("age"), new LongValue(25)));
        select.setSelectBody(plainSelect);
        System.out.println("生成的SQL: " + select.toString());
    }
}
import net.sf.jsqlparser.statement.select.*;

public class GenerateSQL {
    public static void main(String[] args) {
        Select select = new Select();
        PlainSelect plainSelect = new PlainSelect();

        // 设置SELECT字段
        plainSelect.addSelectItems(
            new SelectExpressionItem(new Column("id")),
            new SelectExpressionItem(new Column("name"))
        );

        // 设置FROM表
        plainSelect.setFromItem(new Table("users"));

        // 设置WHERE条件
        plainSelect.setWhere(new EqualsTo(new Column("age"), new LongValue(25)));

        select.setSelectBody(plainSelect);
        System.out.println("生成的SQL: " + select.toString());
    }
}
import net.sf.jsqlparser.statement.select.*;

public class GenerateSQL {
    public static void main(String[] args) {
        Select select = new Select();
        PlainSelect plainSelect = new PlainSelect();

        // 设置SELECT字段
        plainSelect.addSelectItems(
            new SelectExpressionItem(new Column("id")),
            new SelectExpressionItem(new Column("name"))
        );

        // 设置FROM表
        plainSelect.setFromItem(new Table("users"));

        // 设置WHERE条件
        plainSelect.setWhere(new EqualsTo(new Column("age"), new LongValue(25)));

        select.setSelectBody(plainSelect);
        System.out.println("生成的SQL: " + select.toString());
    }
}

结果

SELECT id, name FROM users WHERE age = 25
SELECT id, name FROM users WHERE age = 25
SELECT id, name FROM users WHERE age = 25

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5. 提取SQL信息

从AST中提取表名、字段、条件等关键信息。

示例：提取表名和字段

import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;
public class ExtractInfo {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();
            // 提取表名
            System.out.println("表名: " + plainSelect.getFromItem());
            // 提取字段
            plainSelect.getSelectItems().forEach(item -> {
                if (item instanceof SelectExpressionItem) {
                    System.out.println("字段: " + ((SelectExpressionItem) item).getExpression());
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;

public class ExtractInfo {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();

            // 提取表名
            System.out.println("表名: " + plainSelect.getFromItem());

            // 提取字段
            plainSelect.getSelectItems().forEach(item -> {
                if (item instanceof SelectExpressionItem) {
                    System.out.println("字段: " + ((SelectExpressionItem) item).getExpression());
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.select.*;

public class ExtractInfo {
    public static void main(String[] args) {
        try {
            String sql = "SELECT id, name FROM users WHERE age > 18";
            Select select = (Select) CCJSqlParserUtil.parse(sql);
            PlainSelect plainSelect = (PlainSelect) select.getSelectBody();

            // 提取表名
            System.out.println("表名: " + plainSelect.getFromItem());

            // 提取字段
            plainSelect.getSelectItems().forEach(item -> {
                if (item instanceof SelectExpressionItem) {
                    System.out.println("字段: " + ((SelectExpressionItem) item).getExpression());
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

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6. 处理复杂SQL

解析多语句SQL

通过分割字符串逐条解析（需注意分号、注释等特殊情况）：

String sql = "SELECT * FROM table1; INSERT INTO table2 VALUES (1, 'test');";
String[] statements = sql.split(";");
for (String stmt : statements) {
    if (!stmt.trim().isEmpty()) {
        try {
            Statement statement = CCJSqlParserUtil.parse(stmt);
            System.out.println("解析结果: " + statement);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}
String sql = "SELECT * FROM table1; INSERT INTO table2 VALUES (1, 'test');";
String[] statements = sql.split(";");
for (String stmt : statements) {
    if (!stmt.trim().isEmpty()) {
        try {
            Statement statement = CCJSqlParserUtil.parse(stmt);
            System.out.println("解析结果: " + statement);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}
String sql = "SELECT * FROM table1; INSERT INTO table2 VALUES (1, 'test');";
String[] statements = sql.split(";");
for (String stmt : statements) {
    if (!stmt.trim().isEmpty()) {
        try {
            Statement statement = CCJSqlParserUtil.parse(stmt);
            System.out.println("解析结果: " + statement);
        } catch (JSQLParserException e) {
            e.printStackTrace();
        }
    }
}

处理嵌套查询

JSqlParser支持解析子查询，例如：

SELECT id FROM (SELECT id FROM users WHERE age > 18) AS subquery
SELECT id FROM (SELECT id FROM users WHERE age > 18) AS subquery
SELECT id FROM (SELECT id FROM users WHERE age > 18) AS subquery

解析后可通过AST遍历子查询结构。

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7. 注意事项

1. SQL方言支持：JSqlParser主要支持标准SQL，部分数据库特定语法可能需要自定义处理。
2. 性能优化：解析复杂SQL时，建议缓存AST或分步处理。
3. 错误处理：捕获 JSQLParserException 以处理语法错误。

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8. 应用场景

• SQL审计：检测潜在SQL注入风险。
• SQL改写：动态添加分页、排序等逻辑。
• SQL迁移：将一种数据库的SQL转换为另一种数据库的语法。

通过以上技巧，JSqlParser可显著提升SQL处理的灵活性和效率，适用于数据库工具开发、查询优化等场景。