4. A method performed by a system implemented on a computer for preprocessing print documents that have not yet been printed by a printing plant, the system including a memory configured to store computer programs and a processor configured to realize, when the computer programs stored in the memory are called and executed, a document inputting unit, a document processing unit, and a document outputting unit, wherein the document processing unit comprises one or more document processing sub-units, each of the one or more document processing sub-units comprises a document checking functional module and a document processing functional module, the method comprising: step A, receiving print documents that have not yet been printed by the document inputting unit; step B, performing processing, by the document processing unit, on the print documents that have not yet been printed and are received by the document inputting unit, wherein step B comprises: step B1, determining, by a system scheduling unit, whether there is a document processing sub-unit that has not yet processed the print documents that have not yet been printed among the one or more document processing sub-units, if yes, then step B2, submitting, by the system scheduling unit, the print documents that have not yet been printed to the document processing sub-unit that has not yet processed the print documents that have not yet been printed for processing, otherwise, then step C; step B2 further comprises: step B11, determining, by the document checking functional module, whether the print documents that have not yet been printed comply with a specified standard, if yes, then step C, otherwise, step B12, determining, by the document checking functional module, whether a problem that a part of the print documents that have not yet been printed and do not comply with the specified standard can be solved by the document processing functional module, if yes, step B13, performing processing on the print documents that have not yet been printed and do not comply with the specified standard so as to cause them to comply with the specified standard by the document processing functional module, then step C, otherwise, step B14, terminating the method; and step C, outputting, by the document outputting unit, the print documents that have been processed by the document processing unit.
4. A method performed by a system implemented on a computer for preprocessing print documents that have not yet been printed by a printing plant, the system including a memory configured to store computer programs and a processor configured to realize, when the computer programs stored in the memory are called and executed, a document inputting unit, a document processing unit, and a document outputting unit, wherein the document processing unit comprises one or more document processing sub-units, each of the one or more document processing sub-units comprises a document checking functional module and a document processing functional module, the method comprising: step A, receiving print documents that have not yet been printed by the document inputting unit; step B, performing processing, by the document processing unit, on the print documents that have not yet been printed and are received by the document inputting unit, wherein step B comprises: step B1, determining, by a system scheduling unit, whether there is a document processing sub-unit that has not yet processed the print documents that have not yet been printed among the one or more document processing sub-units, if yes, then step B2, submitting, by the system scheduling unit, the print documents that have not yet been printed to the document processing sub-unit that has not yet processed the print documents that have not yet been printed for processing, otherwise, then step C; step B2 further comprises: step B11, determining, by the document checking functional module, whether the print documents that have not yet been printed comply with a specified standard, if yes, then step C, otherwise, step B12, determining, by the document checking functional module, whether a problem that a part of the print documents that have not yet been printed and do not comply with the specified standard can be solved by the document processing functional module, if yes, step B13, performing processing on the print documents that have not yet been printed and do not comply with the specified standard so as to cause them to comply with the specified standard by the document processing functional module, then step C, otherwise, step B14, terminating the method; and step C, outputting, by the document outputting unit, the print documents that have been processed by the document processing unit. 6. The method according to claim 4 , wherein the document outputting unit comprises a document outputting functional module, and step C comprises: step C1, submitting, by the system scheduling unit, the print documents that have been processed by the document processing unit to the document outputting functional module, and step C2, saving, by the document outputting functional module, the print documents that have been well processed to a specified storage location or submitting the same to a related external system.