线程“main”中的exceptionjava.lang.Error：未解决的编译问题：
嗨，每一个我在我的jdbc代码中有一些问题我试图通过mysql连接，但它会给出error.my错误日志如下，如果你有一些时间请帮助我。
Exception in thread "main" java.lang.Error: Unresolved compilation problems: BLOB cannot be resolved to a type BLOB cannot be resolved to a type at serialize.SerializeDeserialze.main(SerializeDeserialze.java:73) 我的代码如下….我正在使用mysql-connector-java-5.1.20.jar驱动程序
package serialize; /* By vivek */ import java.io.InputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.OutputStream; import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; import oracle.sql.BLOB; /**** CREATE TABLE java_objects (object_id NUMBER, object_name varchar(128), object_value BLOB DEFAULT empty_blob(), primary key (object_id)); SQL> desc java_objects; Name Null? Type ----------------------------------------- -------- ---------------------------- OBJECT_ID NOT NULL NUMBER OBJECT_NAME VARCHAR2(128) OBJECT_VALUE BLOB SQL> select SEQUENCE_NAME, MIN_VALUE, MAX_VALUE, INCREMENT_BY, LAST_NUMBER from user_sequences; SEQUENCE_NAME MIN_VALUE MAX_VALUE INCREMENT_BY LAST_NUMBER ------------------------------ ---------- ---------- ------------ ----------- ID_SEQ 1 1.0000E+27 1 21 JAVA_OBJECT_SEQUENCE 1 1.0000E+27 1 1 */ public class SerializeDeserialze { public static void main(String[] args) throws Exception { String WRITE_OBJECT_SQL = "BEGIN " + " INSERT INTO java_objects(object_id, object_name, object_value) " + " VALUES (?, ?, empty_blob()) " + " RETURN object_value INTO ?; " + "END;"; String READ_OBJECT_SQL = "SELECT object_value FROM java_objects WHERE object_id = ?"; Connection conn = getOracleConnection(); conn.setAutoCommit(false); List list = new ArrayList(); list.add("This is a short string."); list.add(new Integer(1234)); list.add(new java.util.Date()); // write object to Oracle long id = 0001; String className = list.getClass().getName(); CallableStatement cstmt = conn.prepareCall(WRITE_OBJECT_SQL); cstmt.setLong(1, id); cstmt.setString(2, className); cstmt.registerOutParameter(3, java.sql.Types.BLOB); cstmt.executeUpdate(); BLOB blob = (BLOB) cstmt.getBlob(3); OutputStream os = blob.getBinaryOutputStream(); ObjectOutputStream oop = new ObjectOutputStream(os); oop.writeObject(list); oop.flush(); oop.close(); os.close(); // Read object from oracle PreparedStatement pstmt = conn.prepareStatement(READ_OBJECT_SQL); pstmt.setLong(1, id); ResultSet rs = pstmt.executeQuery(); rs.next(); InputStream is = rs.getBlob(1).getBinaryStream(); ObjectInputStream oip = new ObjectInputStream(is); Object object = oip.readObject(); className = object.getClass().getName(); oip.close(); is.close(); rs.close(); pstmt.close(); conn.commit(); // de-serialize list a java object from a given objectID List listFromDatabase = (List) object; System.out.println("[After De-Serialization] list=" + listFromDatabase); conn.close(); } private static Connection getHSQLConnection() throws Exception { Class.forName("org.hsqldb.jdbcDriver"); System.out.println("Driver Loaded."); String url = "jdbc:hsqldb:data/tutorial"; return DriverManager.getConnection(url, "sa", ""); } public static Connection getMySqlConnection() throws Exception { String driver = "org.gjt.mm.mysql.Driver"; String url = "jdbc:mysql://localhost/demo2s"; String username = "oost"; String password = "oost"; Class.forName(driver); Connection conn = DriverManager.getConnection(url, username, password); return conn; } public static Connection getOracleConnection() throws Exception { String driver = "oracle.jdbc.driver.OracleDriver"; String url = "jdbc:oracle:thin:@localhost:1521:databaseName"; String username = "userName"; String password = "password"; Class.forName(driver); // load Oracle driver Connection conn = DriverManager.getConnection(url, username, password); return conn; }
当您使用Eclipse作为IDE并尝试运行甚至不编译的代码时，会发生此错误。 检查Eclipse中的Problems视图，并在执行应用程序之前修复编译错误。
您正在使用MySQL驱动程序，但您的类使用Oracle BLOB类。 使用Oracle JDBC驱动程序，或者为BLOB使用不同的类。
由于您的代码提到了HSQL，MySQL和Oracle，您可能希望摆脱Oracle特定的BLOB实现。