JavaParser
JavaParser is java 1-14 Parser and Abstract Syntax Tree for Java, including preview features to Java 13.
该项目包含一组实现具有高级分析功能的Java 1.0-Java 14 Parser的库。
这包括Java 13的预览功能，以及Java 14的预览功能正在进行中。
学习资料
阅读：https://leanpub.com/javaparservisited/read_full
TODO: 整本书的学习笔记。
入门例子
Sample project with a basic Maven + JavaParser setup
Sample project with basic Maven + JavaSymbolSolver set up
Inspecting an AST
maven 引入
<dependency>
<groupId>com.github.javaparser</groupId>
<artifactId>javaparser-symbol-solver-core</artifactId>
<version>3.15.21</version>
</dependency>
ps: 需要设置 jdk 级别为 1.8
断点
public static void main(String[] args) {
// Parse the code you want to inspect:
CompilationUnit cu = StaticJavaParser.parse("class X { int x; }");
// Now comes the inspection code:
System.out.println(cu);
}
我们可以通过断点的方式获取 "class X { int x; }" 的信息。
输出
// Now comes the inspection code:
YamlPrinter printer = new YamlPrinter(true);
System.out.println(printer.output(cu));
直接输出
---
root(Type=CompilationUnit):
types:
- type(Type=ClassOrInterfaceDeclaration):
isInterface: "false"
name(Type=SimpleName):
identifier: "X"
members:
- member(Type=FieldDeclaration):
variables:
- variable(Type=VariableDeclarator):
name(Type=SimpleName):
identifier: "x"
type(Type=PrimitiveType):
type: "INT"
...
xml 格式
<root type='CompilationUnit'><types><type type='ClassOrInterfaceDeclaration' isInterface='false'><name type='SimpleName' identifier='X'></name><members><member type='FieldDeclaration'><variables><variable type='VariableDeclarator'><name type='SimpleName' identifier='x'></name><type type='PrimitiveType' type='INT'></type></variable></variables></member></members></type></types></root>
修改 class 文件
直接参考 Sample project with a basic Maven + JavaParser setup
maven 引入
<dependency>
<groupId>com.github.javaparser</groupId>
<artifactId>javaparser-core</artifactId>
<version>3.15.21</version>
</dependency>
原始 java 类
ps: 某种角度是为了展现强大，所以代码很冗余，很长。
import com.github.javaparser.utils.CodeGenerationUtils;
import com.github.javaparser.utils.SourceRoot;
public class Blabla {
private final void method1013(StreamBuffer buf, int opcode) {
if (opcode != 1) {
if (opcode != 2) {
if (opcode != 4) {
do {
if (opcode != 5) {
if (opcode == 6)
((Class94) this).anInt1477 = buf.readUnsignedShort();
else {
if (opcode != 7) {
if (opcode != 8) {
if (opcode == 11)
((Class94) this).anInt1456 = 1;
else if (opcode != 12) {
if (opcode != 16) {
if (opcode == 23)
((Class94) this).anInt1424 = (buf.readUnsignedShort());
else if (opcode != 24) {
if (opcode == 25)
((Class94) this).anInt1487 = (buf.readUnsignedShort());
else if (opcode == 26)
anInt1435 = (buf.readUnsignedShort());
else if (opcode < 30 || opcode >= 35) {
if (opcode >= 35 && opcode < 40)
((Class94) this).aStringArray1475[-35 + opcode] = (buf.readString());
else if (opcode == 40) {
int i_48_ = (buf.readUnsignedByte());
aShortArray1457 = (new short[i_48_]);
aShortArray1492 = (new short[i_48_]);
for (int i_49_ = 0; i_49_ < i_48_; i_49_++) {
aShortArray1457[i_49_] = (short) buf.readUnsignedShort();
aShortArray1492[i_49_] = (short) buf.readUnsignedShort();
}
} else if (opcode != 41) {
if (opcode == 42) {
int i_50_ = (buf.readUnsignedByte());
aByteArray1501 = (new byte[i_50_]);
for (int i_51_ = 0; (i_51_ < i_50_); i_51_++) aByteArray1501[i_51_] = (buf.readByte(false));
} else if (opcode != 65) {
if (opcode == 78)
anInt1479 = (buf.readUnsignedShort());
else if (opcode == 79)
anInt1438 = (buf.readUnsignedShort());
else if (opcode != 90) {
if (opcode != 91) {
if (opcode == 92)
anInt1450 = buf.readUnsignedShort();
else if (opcode != 93) {
if (opcode != 95) {
if (opcode != 96) {
if (opcode == 97)
((Class94) this).anInt1474 = buf.readUnsignedShort();
else if (opcode == 98)
((Class94) this).anInt1500 = buf.readUnsignedShort();
else if (opcode < 100 || opcode >= 110) {
if (opcode == 110)
anInt1423 = buf.readUnsignedShort();
else if (opcode != 111) {
if (opcode == 112)
anInt1480 = buf.readUnsignedShort();
else if (opcode != 113) {
if (opcode == 114)
anInt1439 = buf.readByte(false) * 5;
else if (opcode == 115)
((Class94) this).anInt1462 = buf.readUnsignedByte();
else if (opcode != 121) {
if (opcode != 122) {
if (opcode == 125) {
anInt1493 = buf.readByte(false) << 2;
anInt1465 = buf.readByte(false) << 2;
anInt1437 = buf.readByte(false) << 2;
} else if (opcode == 126) {
anInt1498 = buf.readByte(false) << 2;
anInt1470 = buf.readByte(false) << 2;
anInt1446 = buf.readByte(false) << 2;
} else if (opcode == 127) {
((Class94) this).anInt1455 = buf.readUnsignedByte();
((Class94) this).anInt1426 = buf.readUnsignedShort();
} else if (opcode != 128) {
if (opcode == 129) {
((Class94) this).anInt1433 = buf.readUnsignedByte();
((Class94) this).anInt1468 = buf.readUnsignedShort();
} else if (opcode == 130) {
((Class94) this).anInt1440 = buf.readUnsignedByte();
((Class94) this).anInt1483 = buf.readUnsignedShort();
} else if (opcode != 132) {
if (opcode == 249) {
int i_52_ = buf.readUnsignedByte();
if (((Class94) this).aClass194_1472 == null) {
int i_53_ = Class307.calculateSize(i_52_);
((Class94) this).aClass194_1472 = new HashTable(i_53_);
}
for (int i_54_ = 0; i_54_ < i_52_; i_54_++) {
boolean bool = buf.readUnsignedByte() == 1;
int i_55_ = buf.method2507(125);
Node class279;
if (bool)
class279 = new StringNode(buf.readString());
else
class279 = new IntegerNode(buf.readInt());
((Class94) this).aClass194_1472.add((long) i_55_, class279);
}
}
} else {
int i_56_ = buf.readUnsignedByte();
((Class94) this).anIntArray1441 = new int[i_56_];
for (int i_57_ = 0; i_56_ > i_57_; i_57_++) ((Class94) this).anIntArray1441[i_57_] = buf.readUnsignedShort();
}
} else {
((Class94) this).anInt1442 = buf.readUnsignedByte();
((Class94) this).anInt1476 = buf.readUnsignedShort();
}
} else
((Class94) this).anInt1431 = buf.readUnsignedShort();
} else
((Class94) this).anInt1429 = buf.readUnsignedShort();
} else
anInt1458 = buf.readByte(false);
} else
anInt1503 = buf.readUnsignedShort();
} else {
if (((Class94) this).anIntArray1460 == null) {
((Class94) this).anIntArray1460 = new int[10];
((Class94) this).anIntArray1445 = new int[10];
}
((Class94) this).anIntArray1460[-100 + opcode] = buf.readUnsignedShort();
((Class94) this).anIntArray1445[opcode - 100] = buf.readUnsignedShort();
}
} else
((Class94) this).anInt1443 = buf.readUnsignedByte();
} else
((Class94) this).anInt1494 = buf.readUnsignedShort();
} else
anInt1490 = buf.readUnsignedShort();
} else
anInt1466 = buf.readUnsignedShort();
} else
anInt1454 = (buf.readUnsignedShort());
} else
((Class94) this).aBoolean1463 = true;
} else {
int i_58_ = (buf.readUnsignedByte());
aShortArray1504 = (new short[i_58_]);
aShortArray1488 = (new short[i_58_]);
for (int i_59_ = 0; i_59_ < i_58_; i_59_++) {
aShortArray1488[i_59_] = (short) buf.readUnsignedShort();
aShortArray1504[i_59_] = (short) buf.readUnsignedShort();
}
}
} else
((Class94) this).aStringArray1485[opcode + -30] = (buf.readString());
} else
anInt1449 = (buf.readUnsignedShort());
} else
((Class94) this).aBoolean1502 = true;
} else
((Class94) this).anInt1473 = (buf.readInt());
} else {
((Class94) this).anInt1491 = buf.readUnsignedShort();
if (((Class94) this).anInt1491 > 32767)
((Class94) this).anInt1491 -= 65536;
}
} else {
((Class94) this).anInt1425 = buf.readUnsignedShort();
if (((Class94) this).anInt1425 <= 32767)
break;
((Class94) this).anInt1425 -= 65536;
}
break;
}
break;
}
((Class94) this).anInt1444 = buf.readUnsignedShort();
} while (false);
} else
((Class94) this).anInt1436 = buf.readUnsignedShort();
} else
((Class94) this).aString1434 = buf.readString();
} else
anInt1481 = buf.readUnsignedShort();
}
}
核心代码
import com.github.javaparser.ast.CompilationUnit;
import com.github.javaparser.ast.expr.BinaryExpr;
import com.github.javaparser.ast.stmt.IfStmt;
import com.github.javaparser.ast.stmt.Statement;
import com.github.javaparser.ast.visitor.ModifierVisitor;
import com.github.javaparser.ast.visitor.Visitable;
import com.github.javaparser.utils.CodeGenerationUtils;
import com.github.javaparser.utils.Log;
import com.github.javaparser.utils.SourceRoot;
import java.nio.file.Paths;
/**
* Some code that uses JavaParser.
*/
public class LogicPositivizer {
public static void main(String[] args) {
// JavaParser has a minimal logging class that normally logs nothing.
// Let's ask it to write to standard out:
Log.setAdapter(new Log.StandardOutStandardErrorAdapter());
// SourceRoot is a tool that read and writes Java files from packages on a certain root directory.
// In this case the root directory is found by taking the root from the current Maven module,
// with src/main/resources appended.
SourceRoot sourceRoot = new SourceRoot(CodeGenerationUtils.mavenModuleRoot(LogicPositivizer.class).resolve("src/main/resources"));
// Our sample is in the root of this directory, so no package name.
CompilationUnit cu = sourceRoot.parse("", "Blabla.java");
Log.info("Positivizing!");
cu.accept(new ModifierVisitor<Void>() {
/**
* For every if-statement, see if it has a comparison using "!=".
* Change it to "==" and switch the "then" and "else" statements around.
*/
@Override
public Visitable visit(IfStmt n, Void arg) {
// Figure out what to get and what to cast simply by looking at the AST in a debugger!
n.getCondition().ifBinaryExpr(binaryExpr -> {
if (binaryExpr.getOperator() == BinaryExpr.Operator.NOT_EQUALS && n.getElseStmt().isPresent()) {
/* It's a good idea to clone nodes that you move around.
JavaParser (or you) might get confused about who their parent is!
*/
Statement thenStmt = n.getThenStmt().clone();
Statement elseStmt = n.getElseStmt().get().clone();
n.setThenStmt(elseStmt);
n.setElseStmt(thenStmt);
binaryExpr.setOperator(BinaryExpr.Operator.EQUALS);
}
});
return super.visit(n, arg);
}
}, null);
// This saves all the files we just read to an output directory.
sourceRoot.saveAll(
// The path of the Maven module/project which contains the LogicPositivizer class.
CodeGenerationUtils.mavenModuleRoot(LogicPositivizer.class)
// appended with a path to "output"
.resolve(Paths.get("output")));
}
}
结果
import com.github.javaparser.utils.CodeGenerationUtils;
import com.github.javaparser.utils.SourceRoot;
public class Blabla {
private final void method1013(StreamBuffer buf, int opcode) {
if (opcode == 1)
anInt1481 = buf.readUnsignedShort();
else {
if (opcode == 2)
((Class94) this).aString1434 = buf.readString();
else {
if (opcode == 4)
((Class94) this).anInt1436 = buf.readUnsignedShort();
else {
do {
if (opcode != 5) {
if (opcode == 6)
((Class94) this).anInt1477 = buf.readUnsignedShort();
else {
if (opcode == 7) {
((Class94) this).anInt1425 = buf.readUnsignedShort();
if (((Class94) this).anInt1425 <= 32767)
break;
((Class94) this).anInt1425 -= 65536;
} else {
if (opcode == 8) {
((Class94) this).anInt1491 = buf.readUnsignedShort();
if (((Class94) this).anInt1491 > 32767)
((Class94) this).anInt1491 -= 65536;
} else {
if (opcode == 11)
((Class94) this).anInt1456 = 1;
else if (opcode == 12)
((Class94) this).anInt1473 = (buf.readInt());
else {
if (opcode == 16)
((Class94) this).aBoolean1502 = true;
else {
if (opcode == 23)
((Class94) this).anInt1424 = (buf.readUnsignedShort());
else if (opcode == 24)
anInt1449 = (buf.readUnsignedShort());
else {
if (opcode == 25)
((Class94) this).anInt1487 = (buf.readUnsignedShort());
else if (opcode == 26)
anInt1435 = (buf.readUnsignedShort());
else if (opcode < 30 || opcode >= 35) {
if (opcode >= 35 && opcode < 40)
((Class94) this).aStringArray1475[-35 + opcode] = (buf.readString());
else if (opcode == 40) {
int i_48_ = (buf.readUnsignedByte());
aShortArray1457 = (new short[i_48_]);
aShortArray1492 = (new short[i_48_]);
for (int i_49_ = 0; i_49_ < i_48_; i_49_++) {
aShortArray1457[i_49_] = (short) buf.readUnsignedShort();
aShortArray1492[i_49_] = (short) buf.readUnsignedShort();
}
} else if (opcode == 41) {
int i_58_ = (buf.readUnsignedByte());
aShortArray1504 = (new short[i_58_]);
aShortArray1488 = (new short[i_58_]);
for (int i_59_ = 0; i_59_ < i_58_; i_59_++) {
aShortArray1488[i_59_] = (short) buf.readUnsignedShort();
aShortArray1504[i_59_] = (short) buf.readUnsignedShort();
}
} else {
if (opcode == 42) {
int i_50_ = (buf.readUnsignedByte());
aByteArray1501 = (new byte[i_50_]);
for (int i_51_ = 0; (i_51_ < i_50_); i_51_++) aByteArray1501[i_51_] = (buf.readByte(false));
} else if (opcode == 65)
((Class94) this).aBoolean1463 = true;
else {
if (opcode == 78)
anInt1479 = (buf.readUnsignedShort());
else if (opcode == 79)
anInt1438 = (buf.readUnsignedShort());
else if (opcode == 90)
anInt1454 = (buf.readUnsignedShort());
else {
if (opcode == 91)
anInt1466 = buf.readUnsignedShort();
else {
if (opcode == 92)
anInt1450 = buf.readUnsignedShort();
else if (opcode == 93)
anInt1490 = buf.readUnsignedShort();
else {
if (opcode == 95)
((Class94) this).anInt1494 = buf.readUnsignedShort();
else {
if (opcode == 96)
((Class94) this).anInt1443 = buf.readUnsignedByte();
else {
if (opcode == 97)
((Class94) this).anInt1474 = buf.readUnsignedShort();
else if (opcode == 98)
((Class94) this).anInt1500 = buf.readUnsignedShort();
else if (opcode < 100 || opcode >= 110) {
if (opcode == 110)
anInt1423 = buf.readUnsignedShort();
else if (opcode == 111)
anInt1503 = buf.readUnsignedShort();
else {
if (opcode == 112)
anInt1480 = buf.readUnsignedShort();
else if (opcode == 113)
anInt1458 = buf.readByte(false);
else {
if (opcode == 114)
anInt1439 = buf.readByte(false) * 5;
else if (opcode == 115)
((Class94) this).anInt1462 = buf.readUnsignedByte();
else if (opcode == 121)
((Class94) this).anInt1429 = buf.readUnsignedShort();
else {
if (opcode == 122)
((Class94) this).anInt1431 = buf.readUnsignedShort();
else {
if (opcode == 125) {
anInt1493 = buf.readByte(false) << 2;
anInt1465 = buf.readByte(false) << 2;
anInt1437 = buf.readByte(false) << 2;
} else if (opcode == 126) {
anInt1498 = buf.readByte(false) << 2;
anInt1470 = buf.readByte(false) << 2;
anInt1446 = buf.readByte(false) << 2;
} else if (opcode == 127) {
((Class94) this).anInt1455 = buf.readUnsignedByte();
((Class94) this).anInt1426 = buf.readUnsignedShort();
} else if (opcode == 128) {
((Class94) this).anInt1442 = buf.readUnsignedByte();
((Class94) this).anInt1476 = buf.readUnsignedShort();
} else {
if (opcode == 129) {
((Class94) this).anInt1433 = buf.readUnsignedByte();
((Class94) this).anInt1468 = buf.readUnsignedShort();
} else if (opcode == 130) {
((Class94) this).anInt1440 = buf.readUnsignedByte();
((Class94) this).anInt1483 = buf.readUnsignedShort();
} else if (opcode == 132) {
int i_56_ = buf.readUnsignedByte();
((Class94) this).anIntArray1441 = new int[i_56_];
for (int i_57_ = 0; i_56_ > i_57_; i_57_++) ((Class94) this).anIntArray1441[i_57_] = buf.readUnsignedShort();
} else {
if (opcode == 249) {
int i_52_ = buf.readUnsignedByte();
if (((Class94) this).aClass194_1472 == null) {
int i_53_ = Class307.calculateSize(i_52_);
((Class94) this).aClass194_1472 = new HashTable(i_53_);
}
for (int i_54_ = 0; i_54_ < i_52_; i_54_++) {
boolean bool = buf.readUnsignedByte() == 1;
int i_55_ = buf.method2507(125);
Node class279;
if (bool)
class279 = new StringNode(buf.readString());
else
class279 = new IntegerNode(buf.readInt());
((Class94) this).aClass194_1472.add((long) i_55_, class279);
}
}
}
}
}
}
}
}
} else {
if (((Class94) this).anIntArray1460 == null) {
((Class94) this).anIntArray1460 = new int[10];
((Class94) this).anIntArray1445 = new int[10];
}
((Class94) this).anIntArray1460[-100 + opcode] = buf.readUnsignedShort();
((Class94) this).anIntArray1445[opcode - 100] = buf.readUnsignedShort();
}
}
}
}
}
}
}
}
} else
((Class94) this).aStringArray1485[opcode + -30] = (buf.readString());
}
}
}
}
}
break;
}
break;
}
((Class94) this).anInt1444 = buf.readUnsignedShort();
} while (false);
}
}
}
}
}
JavaParser的快速完整API
JavaParser站点的两个API背后的想法迷失在JavaParser网站的黑暗角落。
这是一种尝试：-)
我在这里讨论的API实际上是JavaParser和StaticJavaParser类的API。
快速开始
建立该API的目的是使普通用例尽可能轻松。
最后，此API是完整API的快捷方式的集合。
import static com.github.javaparser.StaticJavaParser.*;
// ...
CompilationUnit cu = parse("class X{}");
StaticJavaParser.parse 处理的是一个完整的 java 文件，你也可以处理一个 File 或者是文件流。
- 编译表达式
Expression expression = StaticJavaParser.parseExpression("1+1");
JavaParser api
建立此API的目的是为了获得存在的所有灵活性，并提供更多性能。
import static com.github.javaparser.ParseStart.*;
import static com.github.javaparser.Providers.provider;
...
JavaParser javaParser = new JavaParser();
ParseResult result = javaParser.parse(COMPILATION_UNIT, provider("class X{}"));
result.ifSuccessful(cu ->
// use cu
);
或者
import static com.github.javaparser.ParseStart.*;
import static com.github.javaparser.Providers.provider;
...
new JavaParser().parse(COMPILATION_UNIT, provider("class X{}")).ifSuccessful(cu ->
System.out.println(cu)
);
完整的API由JavaParser构造函数和整套解析方法组成，其中有一个额外的功能-一个用于实际解析的功能。
它永远不会引发异常。 ParseResult可以告诉您解析是否正常，如果遇到问题，请告诉我们。
重用JavaParser实例将提高速度。
JavaParser实例不是线程安全的！
extra parse方法的第一个参数指示您将传递的源类型。 通常，它是一个编译单元，但是您可以解析表达式，名称等。
额外解析方法的第二个参数提供源代码。 提供者是对任何种类输入的抽象。
完整的API可让您随意组合这些参数。
再次解析Javadoc是一个例外。 为此，您需要JavadocParser。
可以在构造函数中传递配置。
ParserConfiguration configuration = new ParserConfiguration();
JavaParser parser = new JavaParser(configuration);
ParseResult parseResult = parser.parse(EXPRESSION, provider("1+1"));
if (!parseResult.isSuccessful()) {
System.out.println(parseResult.getProblems().toString());
}
// a failed parse does not always mean there is no result.
parseResult.getResult().ifPresent(System.out::println);
if (parseResult.getCommentsCollection().isPresent()) {
// ...
}
一次性分析整个项目
JavaParser非常适合分析Java代码，并提供了一种一次性处理源目录的方法。
但是它缺少分析项目的方法，该项目可能包含多个源目录。
以前的答案是手动创建所有SourceRoot，然后可以对其进行分析。
让我们回顾一下JavaParser存储库的以下示例。
为了解析存储库中的所有文件，您必须手动定义每个模块的根目录，然后使用每个源根目录创建SourceRoot，然后可以对其进行进一步处理。
Path projectRoot = path-to-project-root;
String[] roots = new String[]{
"javaparser-core/src/main/java",
"javaparser-core-testing/src/test/java",
"javaparser-core-generators/src/main/java",
"javaparser-core-metamodel-generator/src/main/java",
"javaparser-symbol-solver-core/src/main/java",
"javaparser-symbol-solver-logic/src/main/java",
"javaparser-symbol-solver-model/src/main/java",
"javaparser-symbol-solver-testing/src/test/java"
};
for (String root : roots) {
SourceRoot sourceRoot = new SourceRoot(projectRoot.resolve(root));
List<ParseResult> parseResults = sourceRoot.tryToParse();
}
我们需要一种自动实现此目的的方法，从而避免了所有人重新发明轮子的麻烦。
为此，我们介绍ProjectRootand CollectionStrategy。
如果仅需要解析Java文件，则仅收集项目中的SourceRoots就足够了。
但是，如果您还想解析java文件中的符号，则还需要收集jar文件。
使用ParserCollectionStrategy或SymbolSolverCollectionStrategy，您可以分别指定要解析还是解析。
以下示例显示如何初始化ProjectRoot：
// only parsing
private final ProjectRoot projectRoot =
new ParserCollectionStrategy()
.collect(root);
// parsing and resolving
private final ProjectRoot projectRoot =
new SymbolSolverCollectionStrategy()
.collect(root);
