Analysis of the implementation principle of incremental compiler framework in the Java class library
Analysis of the implementation principle of incremental compiler framework in the Java class library
Overview
Incremental compilation refers to the compilation process of only re -compilation of changes and dependencies, and does not re -compile the compilation process of the entire project.The incremental compiler framework in the Java class library can significantly reduce the compilation time and improve the work efficiency of developers.This article will analyze the implementation principle of the incremental compiler framework in the Java library and provide relevant Java code examples.
1. Modify detection
The first step of incremental compilation is to detect the change of source code.When the source code file or dependency item is modified, the compiler framework will mark these files and add them to the re -compiled list.In Java, the file system monitor (File System Watcher) can be used to detect the changes in the file.The following is a sample code that uses Java's WatchService class to implement file modification and detection:
import java.io.IOException;
import java.nio.file.*;
import java.nio.file.WatchEvent.Kind;
import static java.nio.file.StandardWatchEventKinds.*;
public class FileWatcher {
public static void main(String[] args) throws IOException, InterruptedException {
// Create a file system monitor
WatchService watcher = FileSystems.getDefault().newWatchService();
// Monitor the file change in the specified directory
Path directory = Paths.get("path/to/directory");
directory.register(watcher, ENTRY_MODIFY);
// Changes in circular surveillance files
while (true) {
WatchKey key = watcher.take();
for (WatchEvent<?> event : key.pollEvents()) {
Kind<?> kind = event.kind();
if (kind == ENTRY_MODIFY) {
System.out.println("File modified: " + event.context());
// Add to the re -compiled list
}
}
key.reset();
}
}
}
2. Re -compile
After detecting changes in the source code, the compiler framework needs to re -compile these code to generate updated class files.The Java compiler provides a programming interface, such as the JavacomPiler class, which can dynamically compile the Java source code at runtime.The following is an example code that uses the JavacomPiler class to re -compile the Java source code:
import javax.tools.*;
public class JavaCompilerExample {
public static void main(String[] args) {
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
// Specify the source code file
Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(Arrays.asList("path/to/Source.java"));
// Set the compilation option
List<String> options = Arrays.asList("-d", "path/to/outputDirectory");
DiagnosticCollector<JavaFileObject> diagnosticCollector = new DiagnosticCollector<>();
JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnosticCollector, options, null, compilationUnits);
// Execute the compilation task
boolean success = task.call();
if (success) {
System.out.println("Compilation successful");
} else {
List<Diagnostic<? extends JavaFileObject>> diagnostics = diagnosticCollector.getDiagnostics();
for (Diagnostic<? extends JavaFileObject> diagnostic : diagnostics) {
System.out.println("Error: " + diagnostic.getMessage(null));
}
}
}
}
3. Build a dependency diagram
When compiling incremental compilation, the compiler framework needs to accurately know the dependency relationship between the source code to determine which code needs to be re -compiled.You can use ABSTRACT SYNTAX TREE) to build a dependency diagram.AST is an abstract representation of the source code, which can identify the dependent relationship between the source code by traversing the AST tree.The following are examples of using the Javaparser library to build AST tree and analyze the dependent relationship:
import com.github.javaparser.JavaParser;
import com.github.javaparser.ast.CompilationUnit;
import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration;
import java.io.FileInputStream;
import java.io.IOException;
public class DependencyAnalyzer {
public static void main(String[] args) throws IOException {
CompilationUnit cu = JavaParser.parse(new FileInputStream("path/to/Source.java"));
// Get the class and interface declaration in the source code
cu.getChildNodesByType(ClassOrInterfaceDeclaration.class).forEach(clazz -> {
System.out.println("Class: " + clazz.getName());
System.out.println("Dependencies: " + clazz.getExtendedTypes());
// Construct a dependency diagram according to the dependency relationship
});
}
}
4. Incremental compiler framework packaging
To facilitate use and extension, the above functions can be encapsulated into an incremental compiler framework.This framework can provide some advanced functions, such as management of incremental compilation tasks, parallel compilation, and error treatment.The following is an example code of a simple incremental compiler framework:
import java.util.*;
public class IncrementalCompiler {
private List<String> modifiedFiles;
public IncrementalCompiler() {
modifiedFiles = new ArrayList<>();
}
public void addModifiedFile(String filePath) {
modifiedFiles.add(filePath);
}
public void compile() {
// Detect the change of the source code
for (String filePath : modifiedFiles) {
// The files that need to be re -compiled
}
// Build a dependency diagram
// Re -compile the source code according to the dependency diagram
}
public static void main(String[] args) {
IncrementalCompiler compiler = new IncrementalCompiler();
compiler.addModifiedFile("path/to/Source.java");
compiler.compile();
}
}
Summarize
The incremental compiler framework in the Java class library achieves the purpose of compiling only changing code by detecting changes in the source code, re -compiling and modified code, and building a dependent relationship diagram.By encapping these functions into an incremental compiler framework, developers can easily compile incremental compilation and improve development efficiency.The example code provided above can help readers better understand the implementation principle of incremental compiler framework in the Java class library.
