利用Eclipse JDT ASTRewrite向java源码添加代码

最新推荐文章于 2019-11-17 16:39:45 发布

翻译最新推荐文章于 2019-11-17 16:39:45 发布 · 1k 阅读

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本文介绍了一个具体的Java代码示例，展示了如何通过AST Rewriting的方式向现有的Java类中添加新的方法调用。此过程涉及使用Eclipse JDT Core库解析Java源文件、创建AST树、进行AST树的修改，并最终将修改后的AST树转换回源代码。

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1、修改前

public class Main {
    public static void main(String[] args) {
    }
    public static void add() {
        int i = 1;
        System.out.println(i);
    }
}

2、修改后

public class Main {
    public static void main(String[] args) {
        add();
    }
    public static void add() {
        int i = 1;
        System.out.println(i);
    }
}

3、源码

private void AddStatements() throws MalformedTreeException, BadLocationException, CoreException {

        IProject project = ResourcesPlugin.getWorkspace().getRoot().getProject("testAddComments");
        IJavaProject javaProject = JavaCore.create(project);
        IPackageFragment package1 = javaProject.getPackageFragments()[0];

        // get first compilation unit
        ICompilationUnit unit = package1.getCompilationUnits()[0];

        // parse compilation unit
        CompilationUnit astRoot = parse(unit);

        // create a ASTRewrite
        AST ast = astRoot.getAST();
        ASTRewrite rewriter = ASTRewrite.create(ast);

        // for getting insertion position
        TypeDeclaration typeDecl = (TypeDeclaration) astRoot.types().get(0);
        MethodDeclaration methodDecl = typeDecl.getMethods()[0];
        Block block = methodDecl.getBody();

        // create new statements for insertion
        MethodInvocation newInvocation = ast.newMethodInvocation();
        newInvocation.setName(ast.newSimpleName("add"));
        Statement newStatement = ast.newExpressionStatement(newInvocation);

        //create ListRewrite
        ListRewrite listRewrite = rewriter.getListRewrite(block, Block.STATEMENTS_PROPERTY);
        listRewrite.insertFirst(newStatement, null);

        TextEdit edits = rewriter.rewriteAST();

        // apply the text edits to the compilation unit
        Document document = new Document(unit.getSource());

        edits.apply(document);

        // this is the code for adding statements
        unit.getBuffer().setContents(document.get());
    }