使用JavaParser进行java源码解析 - viruseeee - 博客园

安宇雨 - 随手采集
2021-12-28 20:03:00
随手采集
0000-未整理-等待研究

JavaParser下载地址：http://code.google.com/p/javaparser/downloads/list

刚开始接触的时候觉得和JDT里的Parser类不太一样。查了一下WiKi，发现它访问编译单元成员，需要调用相应子元素对应的Visitor类的visit（）方法。此方法可以通过复写来实现自己需要的功能。我需要的功能是将编译单元里的所有MethodDeclaration取出，因此利用传递句柄的方式，实现代码如下：

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1 public static List<MethodDeclaration> getMethodList(CompilationUnit cu) { 2 List<MethodDeclaration> methodList = new ArrayList<MethodDeclaration>();
3 new MethodGetterVisitor().visit(cu, methodList); 4
5 return methodList; 6 }
7
8 private static class MethodGetterVisitor extends VoidVisitorAdapter<Object> { 9
10 @SuppressWarnings("unchecked") 11 @Override 12 public void visit(MethodDeclaration n, Object arg) { 13 List<MethodDeclaration> methodList = new ArrayList<MethodDeclaration>(); 14 methodList = (List<MethodDeclaration>) arg; 15 methodList.add(n); 16 } 17 }

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官方还提供了不通过Visitor改变一个类成员方法的示例（相对Visitor更复杂）：

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1 public class MethodChanger { 2
3 public static void main(String[] args) throws Exception { 4 // creates an input stream for the file to be parsed
5 FileInputStream in = new FileInputStream("test.java");
6
7 CompilationUnit cu;
8 try { 9 // parse the file
10 cu = JavaParser.parse(in); 11 } finally { 12 in.close(); 13 } 14
15 // change the methods names and parameters
16 changeMethods(cu); 17
18 // prints the changed compilation unit
19 System.out.println(cu.toString()); 20 } 21
22 private static void changeMethods(CompilationUnit cu) { 23 List<TypeDeclaration> types = cu.getTypes(); 24 for (TypeDeclaration type : types) { 25 List<BodyDeclaration> members = type.getMembers(); 26 for (BodyDeclaration member : members) { 27 if (member instanceof MethodDeclaration) { 28 MethodDeclaration method = (MethodDeclaration) member; 29 changeMethod(method); 30 } 31 } 32 } 33 } 34
35 private static void changeMethod(MethodDeclaration n) { 36 // change the name of the method to upper case
37 n.setName(n.getName().toUpperCase()); 38
39 // create the new parameter
40 Parameter newArg = ASTHelper.createParameter(ASTHelper.INT_TYPE, "value"); 41
42 // add the parameter to the method
43 ASTHelper.addParameter(n, newArg); 44 } 45 }

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最后附上WiKi里给出的编译单元创建示例：

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1 public class ClassCreator { 2
3 public static void main(String[] args) throws Exception { 4 // creates the compilation unit
5 CompilationUnit cu = createCU(); 6
7 // prints the created compilation unit
8 System.out.println(cu.toString());
9 } 10
11 /**
12 * creates the compilation unit 13 */
14 private static CompilationUnit createCU() { 15 CompilationUnit cu = new CompilationUnit(); 16 // set the package
17 cu.setPakage(new PackageDeclaration(ASTHelper.createNameExpr("java.parser.test"))); 18
19 // create the type declaration
20 ClassOrInterfaceDeclaration type = new ClassOrInterfaceDeclaration(ModifierSet.PUBLIC, false, "GeneratedClass"); 21 ASTHelper.addTypeDeclaration(cu, type); 22
23 // create a method
24 MethodDeclaration method = new MethodDeclaration(ModifierSet.PUBLIC, ASTHelper.VOID_TYPE, "main"); 25 method.setModifiers(ModifierSet.addModifier(method.getModifiers(), ModifierSet.STATIC)); 26 ASTHelper.addMember(type, method); 27
28 // add a parameter to the method
29 Parameter param = ASTHelper.createParameter(ASTHelper.createReferenceType("String", 0), "args"); 30 param.setVarArgs(true); 31 ASTHelper.addParameter(method, param); 32
33 // add a body to the method
34 BlockStmt block = new BlockStmt(); 35 method.setBody(block); 36
37 // add a statement do the method body
38 NameExpr clazz = new NameExpr("System"); 39 FieldAccessExpr field = new FieldAccessExpr(clazz, "out"); 40 MethodCallExpr call = new MethodCallExpr(field, "println"); 41 ASTHelper.addArgument(call, new StringLiteralExpr("Hello World!")); 42 ASTHelper.addStmt(block, call); 43
44 return cu; 45 } 46 }