从 Java 注释处理器访问源代码

I had a problem where I had to access some source code (the initializer code for a non-String/non-primitive constant) and got it solved by accessing the source code via the Compiler Tree API.

这是一般配方:

1.创建自定义 TreePathScanner:

private static class CodeAnalyzerTreeScanner extends TreePathScanner<Object, Trees> {

private String fieldName;

private String fieldInitializer;

public void setFieldName(String fieldName) {
    this.fieldName = fieldName;
}

public String getFieldInitializer() {
    return this.fieldInitializer;
}

@Override
public Object visitVariable(VariableTree variableTree, Trees trees) {
    if (variableTree.getName().toString().equals(this.fieldName)) {
        this.fieldInitializer = variableTree.getInitializer().toString();
    }

    return super.visitVariable(variableTree, trees);
}

<强>2.在您的 AbstractProcessor 中，通过覆盖 init 方法保存对当前编译树的引用:

@Override
public void init(ProcessingEnvironment pe) {
    super.init(pe);
    this.trees = Trees.instance(pe);
}

3.获取 VariableElement 的初始化源代码(在您的情况下为枚举):

// assuming theClass is a javax.lang.model.element.Element reference
// assuming theField is a javax.lang.model.element.VariableElement reference
String fieldName = theField.getSimpleName().toString();
CodeAnalyzerTreeScanner codeScanner = new CodeAnalyzerTreeScanner();
TreePath tp = this.trees.getPath(theClass);

codeScanner.setFieldName(fieldName);
codeScanner.scan(tp, this.trees);
String fieldInitializer = codeScanner.getFieldInitializer();

就是这样！最后 fieldInitializer 变量将包含用于初始化我的常量的确切代码行.通过一些调整，您应该能够使用相同的配方来访问源树中其他元素类型的源代码(即方法、包声明等)