使用Eclipse AST来解析Java

Eclipse中有个Outline视图,这个视图内可以显示类的各种信息,包括属性、方法等。同时在这个视图内点击哪里,就能定位的类什么地方。这是个神奇的东西,那么它是如何实现的呢?其实就是AST(Abstract Syntax Tree),抽象语法树了。利用这个来对Java源码进行解析。
另外,Eclipse有一个AST View插件,使用这个能更加的清楚的看到解析后的效果。

Eclipse AST View

依赖的jar包

  • org.eclipse.core.contenttype_3.4.100.v20110423-0524.jar
  • org.eclipse.core.jobs_3.5.101.v20120113-1953.jar
  • org.eclipse.core.resources_3.7.101.v20120125-1505.jar
  • org.eclipse.core.runtime_3.7.0.v20110110.jar
  • org.eclipse.equinox.common_3.6.0.v20110523.jar
  • org.eclipse.equinox.preferences_3.4.2.v20120111-2020.jar
  • org.eclipse.jdt.core_3.7.3.v20120119-1537.jar
  • org.eclipse.osgi_3.7.2.v20120110-1415.jar

这些包都可以在eclipse的plugin目录找到。可能版本有所区别。
如果使用maven管理,经个人试验,直接使用以下dependency也是可以的。

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<dependency>
<groupId>org.eclipse.tycho</groupId>
<artifactId>org.eclipse.jdt.core</artifactId>
<version>3.8.0.v_C03</version>
</dependency>
<dependency>
<groupId>org.eclipse.core</groupId>
<artifactId>org.eclipse.core.runtime</artifactId>
<version>3.6.0.v20100505</version>
</dependency>
<dependency>
<groupId>org.eclipse.core</groupId>
<artifactId>org.eclipse.core.resources</artifactId>
<version>3.6.0.v20100526-0737</version>
</dependency>

如何解析Java

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package cn.shenyanchao.ast;

import org.apache.commons.io.FileUtils;
import org.eclipse.jdt.core.dom.*;

import java.io.File;
import java.io.IOException;
import java.util.List;

/**
* Created with IntelliJ IDEA.
*
* @author shenyanchao
* Date: 6/13/13
* Time: 11:52 AM
*/
public class AstAnalyzer {
public static void main(String[] args) throws IOException {

String javaSource = FileUtils.readFileToString(new File("/home/shenyanchao/IdeaProjects/ast/src/main/java/cn/shenyanchao/from/ShenYanChaoAST.java"));

ASTParser parser = ASTParser.newParser(AST.JLS3);
parser.setSource(javaSource.toCharArray());

// 使用解析器进行解析并返回AST上下文结果(CompilationUnit为根节点)
CompilationUnit result = (CompilationUnit) parser.createAST(null);

result.imports();
result.getPackage();
result.getCommentList();
System.out.println(result.getCommentList().toString());

TypeDeclaration type = (TypeDeclaration) result.types().get(0);
System.out.println("---------Type---------");
System.out.println(type.toString());

MethodDeclaration method = type.getMethods()[0];
method.parameters();
method.isConstructor();

System.out.println("---------Method---------");
System.out.println(method.toString());
method.getName();
method.getModifiers();
Type returnType = method.getReturnType2();
System.out.println("returnType = " + returnType.toString());

Block methodBody = method.getBody();
List<Statement> statementList = methodBody.statements();

System.out.println(statementList.toString());

statementList.get(0);

ExpressionStatement ifs = (ExpressionStatement) method.getBody().statements().get(1);
Assignment expression = (Assignment) ifs.getExpression();
Expression exp = expression.getRightHandSide();

System.out.println(result.toString());
}
}

如何创建Java

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    package cn.shenyanchao.ast;

import org.eclipse.jdt.core.dom.*;

/**
* Created with IntelliJ IDEA.
*
* @author shenyanchao
* Date: 6/13/13
* Time: 11:27 AM
*/
public class AstHelloWorld {

public static void main(String[] args) {
AST ast = AST.newAST(AST.JLS3);
CompilationUnit compilationUnit = ast.newCompilationUnit();

// 创建类
TypeDeclaration programClass = ast.newTypeDeclaration();
programClass.setName(ast.newSimpleName("HelloWorld"));
programClass.modifiers().add(
ast.newModifier(Modifier.ModifierKeyword.PUBLIC_KEYWORD));
compilationUnit.types().add(programClass);

// 创建包
PackageDeclaration packageDeclaration = ast.newPackageDeclaration();
packageDeclaration.setName(ast.newName("cn.shenyanchao.hello"));
compilationUnit.setPackage(packageDeclaration);

MethodDeclaration main = ast.newMethodDeclaration();
main.setName(ast.newSimpleName("main"));
main.modifiers().add(
ast.newModifier(Modifier.ModifierKeyword.PUBLIC_KEYWORD));
main.modifiers().add(ast.newModifier(Modifier.ModifierKeyword.STATIC_KEYWORD));
main.setReturnType2(ast.newPrimitiveType(PrimitiveType.VOID));
programClass.bodyDeclarations().add(main);
Block mainBlock = ast.newBlock();
main.setBody(mainBlock);

// 给main方法定义String[]参数
SingleVariableDeclaration mainParameter = ast
.newSingleVariableDeclaration();
mainParameter.setName(ast.newSimpleName("arg"));
mainParameter.setType(ast.newArrayType(ast.newSimpleType(ast
.newName("String"))));
main.parameters().add(mainParameter);

MethodInvocation println = ast.newMethodInvocation();
println.setName(ast.newSimpleName("println"));

//生成String类型的常量
StringLiteral s = ast.newStringLiteral();
s.setLiteralValue("Hello World");
println.arguments().add(s);

println.setExpression(ast.newName("System.out"));

mainBlock.statements().add(ast.newExpressionStatement(println));

System.out.println(compilationUnit.toString());
}
}

具体的使用手册,参见http://www.shenyanchao.cn/blog/2013/06/07/eclipse-ast/

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