Studieren Sie den zur Aufgabe gehörenden Lehrbrief und lösen Sie die Aufgaben darin. Testen Sie ihre Lösungen zunächst am besten
interaktiv in der JShell.
package name.panitz.util;
import java.util.Set;
import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import javax.tools.Diagnostic.Kind;
import javax.lang.model.type.*;
import java.io.*;
@SupportedAnnotationTypes("name.panitz.util.CheckDataObject")
@SupportedSourceVersion(SourceVersion.RELEASE_16)
public class DataObjectProcessor extends AbstractProcessor {
@Override
public boolean process(Set<?extends TypeElement>as,RoundEnvironment env){
try{
for (var element : env.getElementsAnnotatedWith(CheckDataObject.class)) {
String packageName = ((PackageElement)element.getEnclosingElement())
.getQualifiedName().toString();
var cs = ((TypeElement)element);
generateSetter(packageName,cs);
checkArgumentTypes(packageName,cs);
generateServlet(packageName,cs);
}
return false;
}catch (Exception e){throw new RuntimeException(e);}
}
private void generateSetter(String packageName,TypeElement cs)
throws Exception{
var simpleName = cs.getSimpleName();
var name = simpleName+"Util";
var fqn = packageName != null?packageName+"."+name:name;
var builderFile = processingEnv.getFiler().createSourceFile(fqn);
var out = new PrintWriter(builderFile.openWriter()) ;
if (packageName != null) {
out.append("package ").append(packageName).append(";\n");
}
out.append("public class ").append(name).append("{");
for (var rc:cs.getRecordComponents()){
out.write("\n static public "+simpleName);
out.write(" set"+rc.getSimpleName());
out.write("("+simpleName+" dies, "+ rc.asType() + " v){");
out.write("\n return new "+simpleName+"(");
var first=true;
for (var rc2:cs.getRecordComponents()){
if (first) first=false; else out.write(", ");
if (rc2.getSimpleName().equals(rc.getSimpleName())) out.write("v");
else out.write("dies."+rc2.getSimpleName()+"()");
}
out.append(");").append("\n }");
}
out.write("\n}");
out.close();
}
private void checkArgumentTypes(String packageName,TypeElement cs)
throws Exception{
for (var rc:cs.getRecordComponents()){
if (!isAllowedFieldType(rc.asType()))
processingEnv.getMessager().printMessage
(Kind.ERROR, "illegal field type in DataObject "
+ rc.asType()+ " for field "+rc, cs);
}
}
public static boolean isAllowedFieldType(TypeMirror type) {
if (type instanceof DeclaredType dt) {
if (dt.asElement() instanceof TypeElement ce) {
return
ce.toString().equals("name.panitz.util.UID")
||ce.toString().equals("java.lang.String")
||ce.getInterfaces().stream()
.anyMatch(i->(""+i).equals("name.panitz.util.DataObject"));
}
}else if (type instanceof PrimitiveType){
return !type.toString().equals("char");
}
return false;
}
private void generateServlet(String packageName,TypeElement cs)
throws Exception{
var simpleName = cs.getSimpleName();
var name = simpleName+"Servlet";
var builderFile = processingEnv.getFiler().createSourceFile(name);
var out = new PrintWriter(builderFile.openWriter()) ;
if (packageName != null) {
out.append("package ").append(packageName).append(";\n");
}
out.write(
"""
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import static name.panitz.util.DataObject.*;
public class """);
out.write(" "+name+" ");
out.write(
"""
extends HttpServlet{
@Override
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/xml");
response.setCharacterEncoding("UTF-8");
String requestUri = request.getRequestURI();
String rest = requestUri.substring((request.getContextPath()+"/"""
+simpleName+"/\").length());");
out.write(
"""
if (rest.startsWith("list")){
//TODO
""");
out.write(
"""
}else if (rest.startsWith("get")){
//TODO
""");
out.write(
"""
}else if (rest.startsWith("createTable")){
//TODO
""");
out.write(
"""
}else if (rest.startsWith("save")){
//TODO
""");
out.write(
"""
}else if (rest.startsWith("delete")){
//TODO
""");
out.write(
"""
}else {
response
.getOutputStream()
.println
("<info>no match "+rest+" in "+requestUri+"</info>");
}
}
@Override
public void doPost(HttpServletRequest rq,HttpServletResponse rp)
throws IOException, ServletException {
doGet(rq,rp);
}
}
""");
out.close();
}
}
Subato
