Java 将文件从Struts/JSP上载到数据库中的PostgreSQL大型对象（“lo”/“oid”）

我有一个使用PostgreSQL、JSP和STRUTS框架的应用程序

我想在PostgreSQL中使用OID类型将一个文件插入到一个表中，这样它就作为一个大对象存储在数据库中

我的表定义如下：

CREATE TABLE mensaje
(
  id serial NOT NULL,
  file oid,
  CONSTRAINT pk_mensaje PRIMARY KEY (id)
)
WITH (
  OIDS=TRUE
);
ALTER TABLE mensaje
 OWNER TO postgres;

有人知道

操作

、

操作表单

和

jsp

应该如何使用的例子吗

---

如果没有，是否有其他示例说明如何在不使用OID类型的情况下执行此操作？

这是一个两步过程来解决此问题：

，检查“写入图像”部分

附加说明：在操作中收到文件后，应使用字节数组数据将其保存在

OID

字段中

---

从您的评论来看，Struts1.x应该是这样的

在JSP中

<html:form action="fileUploadAction" method="post" enctype="multipart/form-data">
    File : <html:file property="upload" /> 
    <br />
    <html:submit />
</html:form>

MensajeService

类将连接到您的Postgre数据库并保存文件

public class MensajeService {

    public MensajeService() {
    }

    public void saveFile(int id, byte[] fileData) throws SQLException {
        //this is a very simple skeleton, you have to adapt this to 
        //your needs, the way you're connecting to dabatase, etc...
        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = ... //get the connection to your postgre db

            //Initialize a new transaction
            con.setAutoCommit(false);
            // Get the Large Object Manager to perform operations with
            LargeObjectManager lobj = ((org.postgresql.PGConnection)conn)
                .getLargeObjectAPI();
            // Create a new large object
            int oid = lobj.create(LargeObjectManager.READ | LargeObjectManager.WRITE);
            // Open the large object for writing
            LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);
            //in the provided example, the code shows a way to get the byte array data
            //from the file (using the File and FileInputStream classes)
            //you don't need all that because you already have the byte array (good!)
            //so you only write the binary data in your LargeObject (OID) object
            obj.write(fileData);

            //creating the SQL statement to insert the OID
            String sql = "INSERT INTO mensaje VALUES (?, ?)";
            pstmt = con.prepareStatement(sql);
            pstmt.setInt(1, id);
            ps.setInt(2, oid);
            //
            pstmt.setBinaryStream(2, fin, (int) img.length());
            //saving the file
            pstmt.executeUpdate();
            //closing the transaction successfully
            con.commit();
        } catch (SQLException e) {
            //error in the transaction, start a rollback
            if (con != null) {
                con.rollback();
            }
            throw e;
        } finally {
            //don't forget to free the resources after using them
            pstmt.close();
            con.close();
        }
    }
}

Struts 1代码改编自：

---

PostreSQL代码改编自。

在PostgreSQL中存储文件有三种方法：（a）oid类型作为对

pg_largeobject

的引用；（b） 作为表列中的

bytea

值，最好仅用于较小的文件；（c） 在文件系统外部，仅在数据库中存储文件名。请参阅前面的回答：对不起，我编辑了标签。这也适用于Struts 1吗？

public class MensajeService {

    public MensajeService() {
    }

    public void saveFile(int id, byte[] fileData) throws SQLException {
        //this is a very simple skeleton, you have to adapt this to 
        //your needs, the way you're connecting to dabatase, etc...
        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = ... //get the connection to your postgre db

            //Initialize a new transaction
            con.setAutoCommit(false);
            // Get the Large Object Manager to perform operations with
            LargeObjectManager lobj = ((org.postgresql.PGConnection)conn)
                .getLargeObjectAPI();
            // Create a new large object
            int oid = lobj.create(LargeObjectManager.READ | LargeObjectManager.WRITE);
            // Open the large object for writing
            LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);
            //in the provided example, the code shows a way to get the byte array data
            //from the file (using the File and FileInputStream classes)
            //you don't need all that because you already have the byte array (good!)
            //so you only write the binary data in your LargeObject (OID) object
            obj.write(fileData);

            //creating the SQL statement to insert the OID
            String sql = "INSERT INTO mensaje VALUES (?, ?)";
            pstmt = con.prepareStatement(sql);
            pstmt.setInt(1, id);
            ps.setInt(2, oid);
            //
            pstmt.setBinaryStream(2, fin, (int) img.length());
            //saving the file
            pstmt.executeUpdate();
            //closing the transaction successfully
            con.commit();
        } catch (SQLException e) {
            //error in the transaction, start a rollback
            if (con != null) {
                con.rollback();
            }
            throw e;
        } finally {
            //don't forget to free the resources after using them
            pstmt.close();
            con.close();
        }
    }
}