SoFunction
Updated on 2025-04-13

Java implements multiple document merging

1. Project background and introduction

1.1 Project Overview

In practical applications, we often need to merge multiple scattered document files into a complete document, such as the summary of log files, the integration of data reports, the merger of configuration files, etc. Manual merging is not only time-consuming and labor-intensive, but also error-prone, so implementing an automated document merging tool has practical significance.

This project uses Java to implement a simple and general document merging tool, mainly targeting text files merging. You can easily read the contents of multiple text files and splice them into a complete file, while ensuring the correctness of file encoding and formatting.

1.2 Development Motives and Application Scenarios

The main motivations for developing document merging tools include:

  • Improve efficiency: Automatically merging documents can greatly reduce manual operations and improve data processing efficiency.
  • Reduce error rate: The program automatically handles the format and content errors that may occur when copying and pasting manually.
  • Widely used: Document merging tools have practical application scenarios in the fields of log summary, report generation, data backup, etc.
  • Learning and Practice: Implementing document merging can help developers become familiar with key technologies such as Java I/O operations, exception handling, and performance optimization.

1.3 The significance of document merging

Document merging refers to integrating multiple independent file contents into a complete document. It can not only be used for data sorting and reporting generation, but also as part of text preprocessing, which facilitates subsequent data analysis and processing.

2. Selection of relevant theoretical knowledge and technology

2.1 Document file type and basic format

This article focuses on the merging of text files (such as .txt files). Text files usually store plain text data in UTF-8 or other common encoding formats, and their contents can be read and written through a character stream.

2.2 Basics of text file operation

In Java, the operation of text files mainly depends on the following classes:

  • FileReader / FileWriter: Suitable for character stream reading and writing.
  • BufferedReader/BufferedWriter: Provides buffering function to improve read and write efficiency.
  • Files class (Java 7 and above): Provides NIO file operation interface.

2.3 Java I/O basics

Java I/O includes two major systems: byte stream and character stream. For text files, we mainly use character streams (Reader/Writer) combined with buffered streams for efficient operations, and at the same time use the Files class for simple file reading and writing.

2.4 Performance and exception handling

  • Performance: Using BufferedReader and BufferedWriter can significantly reduce disk I/O times and improve merge speeds. For large file merging, chunked reads and writes can also be considered.
  • Exception handling: During file operation, exceptions such as IOException, file encoding errors, etc. should be caught and handled appropriately to ensure the program runs smoothly.

2.5 Technical selection

This project does not rely on third-party libraries, and uses Java built-in class libraries to complete file merging operations. If you need to support formats such as PDF and Word, you may need Apache PDFBox and Apache POI. The examples in this article are mainly aimed at plain text files.

3. System architecture and module design

3.1 Overall architecture design

The overall architecture of this document merger tool is mainly divided into three layers:

  • Data input layer: Read the content of multiple text files.
  • Merge processing layer: splice the read content to generate the content of a complete document.
  • Output layer: Write the merged document content into the target file, and provide log information and error prompts.

3.2 Main module division

DocumentReader module: Responsible for reading all contents of a single text file and handling file encoding issues.

DocumentMerger module: Responsible for merging the contents of multiple documents, which can be merged in order, or you can add delimiters or titles as needed.

DocumentWriter module: Responsible for writing the merged content to the target document and handling possible exceptions when writing files.

Main class: As a program entrance, it accepts input parameters (such as file path list, target file path), calls the corresponding module to complete document merging, and outputs logs.

3.3 Class diagrams and flow diagrams

The following is an example of the system class diagram:

classDiagram
    class DocumentReader {
      + String readDocument(String filePath)
    }
    
    class DocumentMerger {
      + String mergeDocuments(List<String> documents)
    }
    
    class DocumentWriter {
      + void writeDocument(String filePath, String content)
    }
    
    class Main {
      + main(String[] args)
    }
    
Main --> DocumentReader: Call
Main --> DocumentMerger: Call
Main --> DocumentWriter: Call

Flowchart example:

flowchart TD
A[get the list of documents to be merged] --> B[Read document content one by one]
B --> C [Merge everything into one large string]
C --> D[Write to target file]
D --> E[Output merge completion prompt]

4. Project implementation ideas and detailed design

4.1 Requirements Analysis and Core Functions

Document merging tools need to implement the following functions:

  • Read text files with multiple specified paths and deal with encoding issues;
  • Merge all document content in the specified order, supporting the addition of delimiters or titles;
  • Write the merged content to the target file;
  • Exception processing is performed for cases such as file not exist, read errors, and write failures.

4.2 Data reading and variable combination generation

Read file content:

Use BufferedReader to read the file contents, use StringBuilder to splice each line of data, and add newlines to ensure the format is correct.

Supports multiple encodings:

You can use (Path, Charset) to specify the encoding to read the file to ensure that Chinese or other characters are not garbled.

4.3 Expression evaluation and dynamic calculation

In document merging, dynamic evaluation is not involved, but it can provide an extended interface, such as automatically adding dynamic information such as merge date, file title, etc. during merging. The text content will be merged directly in this example.

4.4 Error handling and scalability design

Error handling:

For files that do not exist, read or write exceptions, catch IOException and prompt the user; logs can be recorded to track problems.

Extensible design:

Adopting a modular design, DocumentReader, DocumentMerger and DocumentWriter are all independently implemented, which facilitates subsequent expansion to support document merging in more formats (such as PDF and Word) or provide a graphical interface.

5. Complete code implementation and detailed comments

5.1 Overall code structure description

The code of this project is integrated into a Java file, mainly including the following classes:

DocumentReader class: implements reading file content from a specified path.

DocumentMerger class: implements the merge of multiple document content.

DocumentWriter class: implements the merged content to the target file.

Main class: program entrance, construct test data (such as file path list), call the above module to complete document merging, and output the results.

5.2 Java implements complete source code for document merging

/**
  * @Title:
  * @Description: Use Java to implement document merging tools,
  * This tool is able to combine the contents of multiple text files into a complete document.
  * Use BufferedReader to read the file content in the code, and use StringBuilder to splice it.
  * Finally, use BufferedWriter to write the result to the target file.  It is accompanied by detailed comments to facilitate understanding of the implementation process and expansion ideas.
  * @Author: [Your name]
  * @Date: [Date]
  */
 
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
import ;
 
/**
  * DocumentReader class is used to read the entire contents of a single text file.
  */
class DocumentReader {
    /**
      * Read the text file content of the specified path
      * @param filePath file path
      * @return File content string
      * @throws IOException If the file is read incorrectly
      */
    public String readDocument(String filePath) throws IOException {
        StringBuilder content = new StringBuilder();
        // Use the specified UTF-8 encoding to read the file        try (BufferedReader reader = ((filePath), StandardCharsets.UTF_8)) {
            String line;
            while ((line = ()) != null) {
                (line).append(());
            }
        }
        return ();
    }
}
 
/**
  * DocumentMerger class is used to merge multiple document content.
  */
class DocumentMerger {
    /**
      * Merge multiple document contents and splice them with the specified delimiter.
      * @param documents list of document content
      * @param separator separator string (for example "\n-----\n")
      * @return The merged document content
      */
    public String mergeDocuments(List&lt;String&gt; documents, String separator) {
        StringBuilder merged = new StringBuilder();
        for (int i = 0; i &lt; (); i++) {
            ((i));
            if (i &lt; () - 1) {
                (separator);
            }
        }
        return ();
    }
}
 
/**
  * DocumentWriter class is used to write text content to the target file.
  */
class DocumentWriter {
    /**
      * Write content to the file with the specified path
      * @param filePath target file path
      * @param content what to write
      * @throws IOException If an error occurred during writing
      */
    public void writeDocument(String filePath, String content) throws IOException {
        // Write to the file using BufferedWriter, specify UTF-8 encoding        try (BufferedWriter writer = ((filePath), StandardCharsets.UTF_8)) {
            (content);
        }
    }
}
 
/**
  * Main class is a program entry, demonstrating how to use the document merging tool to complete the merge operation of multiple text files.
  */
public class Main {
    public static void main(String[] args) {
        // Define the path list of files to be merged (can be modified to command line parameters or configuration files according to actual conditions)        List&lt;String&gt; filePaths = new ArrayList&lt;&gt;();
        ("");
        ("");
        ("");
        
        // Define the path to the merged target file        String outputFilePath = "merged_document.txt";
        // Define the separator between documents        String separator = () + "-----" + ();
        
        DocumentReader reader = new DocumentReader();
        DocumentMerger merger = new DocumentMerger();
        DocumentWriter writer = new DocumentWriter();
        
        List&lt;String&gt; documents = new ArrayList&lt;&gt;();
        // Read all document content        for (String path : filePaths) {
            try {
                String content = (path);
                (content);
                ("Read the document successfully:" + path);
            } catch (IOException e) {
                ("Read Documents" + path + " fail:" + ());
            }
        }
        
        // Merge the document content        String mergedContent = (documents, separator);
        try {
            (outputFilePath, mergedContent);
            ("Document merge successfully, output file:" + outputFilePath);
        } catch (IOException e) {
            ("Writing to the target file failed:" + ());
        }
    }
}

6. Code interpretation

6.1 Function description of main classes and methods

DocumentReader class

Responsible for reading text content from the specified file path. Use Java NIO's () to specify UTF-8 encoding to read the file content line by line, and use StringBuilder to splice it to return the complete text string.

DocumentMerger Class

Receives a list of strings, each representing the contents of a document, and then splicing them into a complete string based on the specified delimiter. This allows the content of each sub-document to be clearly separated in the merged document.

DocumentWriter Class

Write the merged content to the target file. Use () to write to the file and specify the encoding format at the same time to ensure that Chinese and special characters are output correctly.

Main Class

The program entrance defines the document path and output file path that need to be merged, calls each module to read, merge and write files in sequence, and finally outputs prompt information. In the sample code, exceptions are caught through try-catch and error messages are output to ensure the robustness of the program.

6.2 Core process analysis

File reading: Iterate through the entered file path list, read the file content one by one through DocumentReader, and store the read results in a List.

Content merge: Pass all the read document content into the () method, splicing it according to the specified delimiter, and generate the final merged text string.

File writing: Write the merged content into the target file through () to complete the entire document merging process.

7. Testing scheme and performance analysis

7.1 Test environment and test data

Development environment: Use JDK 1.8 or higher, IntelliJ IDEA or Eclipse is recommended for development and debugging.

Running platform: Windows and Linux can run.

Test data: Prepare several text files (for example, , ) in advance, the content can be plain text or contains multiple lines of data to test the document merging function.

7.2 Main functional test cases

Basic merge test: Enter multiple existing text file paths to verify that the content in the output file correctly contains all source file content and separators.

Exception handling test: Test whether the program outputs an error prompt and continues to process other files when an input file does not exist or cannot be read.

Encoding test: Test whether documents containing Chinese or special characters will not be garbled after being merged.

7.3 Performance indicators and optimization suggestions

Performance metrics:

  • File reading and writing speed (for large files and large files).
  • Memory usage (using BufferedReader/BufferedWriter buffering operations reduces memory consumption).

Optimization suggestions:

  • For large file merging, you can consider reading and writing in chunks to avoid loading everything into memory at once.
  • Multiple files are read asynchronously with multithreading and then merge the results to improve overall efficiency.
  • For frequent merge operations, the cache mechanism can be added to reduce the number of disk I/O times.

8. Project Summary and Future Outlook

8.1 Project gains and experience summary

Through this project, we have implemented a Java-based document merging tool in detail and mastered the following key technologies:

  • Efficient reading and writing text files with the Java NIO API.
  • The separator design enables neat splicing of multiple document contents.
  • Use exception capture mechanism to ensure the robustness of file operations.
  • Modular design ideas help subsequent expansions support document merging in more formats.

8.2 Follow-up optimization and expansion direction

In the future, projects can be expanded and optimized in the following aspects:

Supports other document formats: Extended to support the merger of PDF and Word documents (Apache PDFBox and Apache POI can be used).

Graphical interface: Develop a graphical user interface, allowing users to intuitively select files, set separators, and preview the merge results.

Multi-threading and asynchronous processing: parallel reading and merging of large amounts of files to improve efficiency in large data scenarios.

Configuration and logging: Dynamically adjust parameters through configuration files and log the merge process, which is easy to debug and monitor.

9. Appendix: FAQs and Solutions

Question 1: Is there an encoding error or garbled code when reading the file?

Solution: Make sure to specify the correct encoding when reading the file (e.g. UTF-8) and use the same encoding when writing to the file.

Question 2: Is an input file not present or inaccessible?

Solution: Perform a file existence check before reading the file. If the file does not exist, record the error message and skip the file.

Question 3: Is the merged document format confusing?

Solution: You can customize the separator when merging to ensure that there is a clear separation between each document content, while dealing with the problem of end-of-line newlines.

Conclusion

This article provides a comprehensive introduction to how to use Java to implement a document merging tool from project background, truth table and Boolean logic foundation (extended to document merging), system architecture design, detailed implementation ideas, to complete code (with detailed notes), code interpretation, test plan and performance analysis, to project summary and future prospects. Through this project, you not only learn how to read, merge and write text files, but also understand the key technologies of modular design, exception handling and performance optimization, providing an effective solution for subsequent processing of log files, report generation and other scenarios.

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