由于我尝试测试有状态EJB,因此出现“ java.lang.ClassCastException:java.lang.String无法转换为com.tutorial.stateful.Book”错误。
我的客户代码如下
import com.tutorial.stateful.LibraryStatefulSessionBeanRemote;
import com.tutorial.stateful.Book;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.Properties;
import javax.naming.InitialContext;
import javax.naming.NamingException;
public class EJBTesterStateful {
BufferedReader brConsoleReader = null;
Properties props;
InitialContext ctx;
{
props = new Properties();
try {
props.load(new FileInputStream("jndi.properties"));
} catch (IOException ex) {
ex.printStackTrace();
}
try {
ctx = new InitialContext(props);
} catch (NamingException ex) {
ex.printStackTrace();
}
brConsoleReader =
new BufferedReader(new InputStreamReader(System.in));
}
public static void main(String[] args) {
EJBTesterStateful ejbTester = new EJBTesterStateful();
ejbTester.testStatefulEjb();
}
private void showGUI(){
System.out.println("**********************");
System.out.println("Welcome to Book Store");
System.out.println("**********************");
System.out.print("Options \n1. Add Book\n2. Exit \nEnter Choice: ");
}
private void testStatefulEjb(){
try {
int choice = 1;
LibraryStatefulSessionBeanRemote libraryBean =
(LibraryStatefulSessionBeanRemote)ctx.lookup("ejb:/EjbComponent//LibraryStatefulSessionBean!com.tutorial.stateful.LibraryStatefulSessionBeanRemote?stateful");
while (choice != 2) {
String bookName;
showGUI();
String strChoice = brConsoleReader.readLine();
choice = Integer.parseInt(strChoice);
if (choice == 1) {
System.out.print("Enter book name: ");
bookName = brConsoleReader.readLine();
Book book = new Book();
book.setName(bookName);
libraryBean.addBook(book.toString());
} else if (choice == 2) {
break;
}
}
List<Book> booksList = libraryBean.getBooks();
System.out.println("Book(s) entered so far: " + booksList.size());
int i = 0;
// Exception line-trigger
for(Book book:booksList){
System.out.println((i+1)+". " + book.getName());
}
LibraryStatefulSessionBeanRemote libraryBean1 =
(LibraryStatefulSessionBeanRemote)ctx.lookup("ejb:/EjbComponent//LibraryStatefulSessionBean!com.tutorial.stateful.LibraryStatefulSessionBeanRemote?stateful");
List<String> booksList1 = libraryBean1.getBooks();
System.out.println(
"***Using second lookup to get library stateful object***");
System.out.println(
"Book(s) entered so far: " + booksList1.size());
for ( i = 0; i < booksList1.size(); ++i) {
System.out.println((i+1)+". " + booksList1.get(i));
}
} catch (Exception e) {
System.out.println(e.getMessage());
e.printStackTrace();
}finally {
try {
if(brConsoleReader !=null){
brConsoleReader.close();
}
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
}
}
}
the statefull ejb class looks like:
@Stateful
public class LibraryStatefulSessionBean implements LibraryStatefulSessionBeanRemote{
List<String> bookShelf;
public LibraryStatefulSessionBean(){
bookShelf = new ArrayList<String>();
}
public void addBook(String bookName) {
bookShelf.add(bookName);
}
public List<String> getBooks() {
return bookShelf;
}
}
解决这个铸造问题有什么主意。
非常感谢
谢谢,您的回答对避免有状态Bean类中的某些更改后避免转换问题很有帮助:
最佳答案
getBooks
返回字符串的List
而不是书本
List<String> booksList = libraryBean.getBooks(); // as you've already done for booksList1
for (String book: booksList){
....
}