将数组从Java传递到Oracle：java.sql.SQLException：无法转换为内部表示形式：错误

Question

我在DAO中有以下内容，当我执行时，我得到了

java.sql.SQLException：无法转换为内部表示形式：test.Project@843

DAO代码

List projectList = new LinkedList();

public void saveRecord(List<Project> project) 
                       throws DatabaseException,SQLException {

    for (Project items: project) {
        insertRecord(items);
    }
}

private void insertRecord(Project project) throws SQLException {
    projectList.add(project);
    try{
        ArrayDescriptor desc = 
                ArrayDescriptor.createDescriptor("MY_ARRAY", dbConn);

        // execpetion in this line
        ARRAY arr = new ARRAY(desc, dbConn, (Object[])projectList.toArray());

我该如何解决这个问题？

编辑1

CREATE OR REPLACE TYPE project_type as object( 
proj_id varchar2 (10),
proj_title varchar2 (10));


create or replace  type my_array as Table of project_type;

Answer 1

不幸的是，这比人们预期的要复杂。您必须使用STRUCT对象，描述符，最后使用ARRAY。下面是一个工作示例。

-- Database code --

CREATE TABLE project_types (
  proj_id VARCHAR2(10),
  proj_title VARCHAR2(10)
);
/

CREATE OR REPLACE TYPE project_type AS OBJECT ( 
  proj_id VARCHAR2(10),
  proj_title VARCHAR2(10)
);
/

CREATE OR REPLACE TYPE my_array AS TABLE OF project_type;
/

CREATE OR REPLACE PROCEDURE add_projects(p_projects_array IN my_array)
AS
BEGIN
  IF p_projects_array IS NOT NULL THEN
    FOR v_i IN 1..p_projects_array.LAST
    LOOP
      INSERT INTO project_types
        VALUES (p_projects_array(v_i).proj_id,
                p_projects_array(v_i).proj_title);
    END LOOP;
  END IF;
END;
/



// Java code - main class

import java.sql.Connection;
import java.sql.DriverManager;

import oracle.jdbc.OracleCallableStatement;
import oracle.jdbc.OracleConnection;
import oracle.sql.ARRAY;
import oracle.sql.ArrayDescriptor;
import oracle.sql.STRUCT;
import oracle.sql.StructDescriptor;

public class ArrayExampleMain {

  public static void main(String[] args) throws Exception {
    OracleConnection conn = getOracleConnection().unwrap(OracleConnection.class);
    System.out.println("Got Connection.");

    OracleCallableStatement callStmt = null;

    try {
      callStmt = (OracleCallableStatement)conn.prepareCall("{call add_projects(?)}");

      // create array holding values for ProjectType object's properties
      Object[] project1 = new Object[] {"1", "Title 1"};
      Object[] project2 = new Object[] {"2", "Title 2"};

      // descriptor for OBJECT type defined in database
      StructDescriptor projectTypeDesc = StructDescriptor.createDescriptor("PROJECT_TYPE", conn);

      // each struct is one ProjectType object
      STRUCT structProject1 = new STRUCT(projectTypeDesc, conn, project1);
      STRUCT structProject2 = new STRUCT(projectTypeDesc, conn, project2);

      STRUCT[] structArrayOfProjects = {structProject1, structProject2};

      // descriptor of TABLE type defined in database
      ArrayDescriptor projectTypeArrayDesc = ArrayDescriptor.createDescriptor("MY_ARRAY", conn);

      // array holding two ProjectType objects
      ARRAY arrayOfProjects = new ARRAY(projectTypeArrayDesc, conn, structArrayOfProjects);

      callStmt.setARRAY(1, arrayOfProjects); 
      callStmt.execute();
      conn.commit();

      System.out.println("Committed.");
    } catch (Exception e) {
      if (conn != null) try { conn.rollback(); } catch (Exception ex) { System.out.println("Rollback failed."); }
      throw e;
    } finally {
      callStmt.close();
      conn.close();
     }
  }

  public static Connection getOracleConnection() throws Exception {
    String driver = "oracle.jdbc.driver.OracleDriver";
    String url = "jdbc:oracle:thin:@YOUR_HOST:orcl";
    String username = "hr";
    String password = "password";

    Class.forName(driver); // load Oracle driver

    Connection conn = DriverManager.getConnection(url, username, password);

    return conn;
  }
}

project_types执行主类后检查表的内容：

SELECT * FROM project_types;

输出：

PROJ_ID PROJ_TITLE
---------- ----------
1标题1    
2标题2