mybatis 拦截器如何通过Invocation获取完整sql

语句并进行修改？

Mybatis拦截器可以通过Invocation对象获取完整的SQL语句并进行修改。在拦截器的intercept方法中，可以获取到方法调用的相关信息，包括Mapper接口、方法名、方法参数等。通过这些信息，可以获取到BoundSql对象，它包含了原始的SQL语句和参数信息。可以通过BoundSql对象获取完整的SQL语句并进行修改，然后再将修改后的SQL语句设置回BoundSql对象即可。

具体实现可以参考以下代码：

public Object intercept(Invocation invocation) throws Throwable {
    Object[] args = invocation.getArgs();
    MappedStatement mappedStatement = (MappedStatement) args[0];
    Object parameterObject = args[1];
    BoundSql boundSql = mappedStatement.getBoundSql(parameterObject);
    String sql = boundSql.getSql();

    // 在这里对SQL语句进行修改
    String newSql = modifySql(sql);

    // 将修改后的SQL语句重新设置回BoundSql对象中
    BoundSql newBoundSql = new BoundSql(mappedStatement.getConfiguration(), newSql, boundSql.getParameterMappings(), parameterObject);
    MappedStatement newMappedStatement = copyFromMappedStatement(mappedStatement, new BoundSqlSqlSource(newBoundSql));
    args[0] = newMappedStatement;
    return invocation.proceed();
}

private String modifySql(String sql) {
    // 在这里可以对SQL语句进行修改，例如添加分页的limit条件
    return "select * from (" + sql + ") limit 0, 10";
}

private MappedStatement copyFromMappedStatement(MappedStatement mappedStatement, SqlSource newSqlSource) {
    MappedStatement.Builder builder = new MappedStatement.Builder(mappedStatement.getConfiguration(), mappedStatement.getId(), newSqlSource, mappedStatement.getSqlCommandType());
    builder.resource(mappedStatement.getResource());
    builder.fetchSize(mappedStatement.getFetchSize());
    builder.statementType(mappedStatement.getStatementType());
    builder.keyGenerator(mappedStatement.getKeyGenerator());
    builder.keyProperty(mappedStatement.getKeyProperty());
    builder.timeout(mappedStatement.getTimeout());
    builder.parameterMap(mappedStatement.getParameterMap());
    builder.resultMaps(mappedStatement.getResultMaps());
    builder.cache(mappedStatement.getCache());
    builder.useCache(mappedStatement.isUseCache());
    return builder.build();
}