利用 Oracle 数据库存储图片的 C 语言实现(c oracle存储图片)
利用 Oracle 数据库存储图片的 C 语言实现
在许多应用程序中,存储和管理图片数据是非常重要的。传统的做法是将图片文件存储到文件系统中,但是这种方式存在一些问题,比如安全性和可维护性等问题。为了解决这些问题,可以使用数据库来存储和管理图片数据。本文将介绍如何使用 C 语言和 Oracle 数据库来实现图片存储和管理。
步骤1:连接到 Oracle 数据库
在 C 语言中连接到 Oracle 数据库。可以使用 Oracle Instant Client 或 Oracle ODBC Driver 来连接到 Oracle 数据库。以下是一个使用 Oracle Instant Client 连接到 Oracle 数据库的示例:
#include
#include
#include
int mn(void)
{
OCIEnv *env;
OCIError *err;
OCISvcCtx *svc;
ociinitialize(OCI_THREADED|OCI_OBJECT, NULL, NULL, NULL, NULL);
OCIEnvCreate(&env, OCI_DEFAULT, NULL, NULL, NULL, NULL, 0, NULL);
OCIHandleAlloc(env, (void **)&err, OCI_HTYPE_ERROR, 0, NULL);
OCIHandleAlloc(env, (void **)&svc, OCI_HTYPE_SVCCTX, 0, NULL);
if (OCILogon(env, err, &svc, “user”, strlen(“user”),
“password”, strlen(“password”), “db”, strlen(“db”), OCI_DEFAULT) == OCI_SUCCESS)
{
printf(“Connected to Oracle database!\n”);
// Do some database operations here
OCILogoff(svc, err);
}
else
{
printf(“Fled to connect to Oracle database!\n”);
}
OCIHandleFree((void *)svc, OCI_HTYPE_SVCCTX);
OCIHandleFree((void *)err, OCI_HTYPE_ERROR);
OCIHandleFree((void *)env, OCI_HTYPE_ENV);
return 0;
}
步骤2:创建表
接下来,在 Oracle 数据库中创建一个用于存储图片的表。以下是一个示例表:
CREATE TABLE images
(
image_id INT PRIMARY KEY,
image_name VARCHAR2(255),
create_date DATE,
image_data BLOB
);
在此表中,image_id 是图片 ID,image_name 是图片名,create_date 是图片创建日期,image_data 是存储图片数据的 BLOB 类型列。
步骤3:将图片存储到 Oracle 数据库中
现在,我们可以将图片存储到 Oracle 数据库中。以下是一个将图片存储到 Oracle 数据库的示例:
#include
#include
#include
#include
int mn(void)
{
OCIEnv *env;
OCIError *err;
OCISvcCtx *svc;
OCIServer *srv;
OCIDefine *def;
OCIBind *bnd;
OCILobLocator *blob;
char *image_data;
int image_size;
char *image_name;
char *sql;
int image_id;
// Connect to Oracle database
if (OCIHandleAlloc(env, (void **)&srv, OCI_HTYPE_SERVER, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate server handle!\n”);
return -1;
}
if (OCIHandleAlloc(env, (void **)&svc, OCI_HTYPE_SVCCTX, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate service handle!\n”);
return -1;
}
OCIAttrSet(svc, OCI_HTYPE_SVCCTX, srv, 0, OCI_ATTR_SERVER, err);
if (OCIHandleAlloc(env, (void **)&err, OCI_HTYPE_ERROR, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate error handle!\n”);
return -1;
}
ociinitialize(OCI_THREADED|OCI_OBJECT, NULL, NULL, NULL, NULL);
OCIEnvCreate(&env, OCI_DEFAULT, NULL, NULL, NULL, NULL, 0, NULL);
if (OCIHandleAlloc(env, (void **)&svc, OCI_HTYPE_SVCCTX, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate service context handle!\n”);
return -1;
}
if (OCIHandleAlloc(env, (void **)&err, OCI_HTYPE_ERROR, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate error handle!\n”);
return -1;
}
if (OCIHandleAlloc(env, (void **)&blob, OCI_HTYPE_LOB, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate lob handle!\n”);
return -1;
}
// Read image file into memory
image_data = read_image_file(“image.jpg”, &image_size);
// Prepare SQL statement
sql = “INSERT INTO images(image_id, image_name, create_date, image_data) VALUES(:1, :2, SYSDATE, :3)”;
OCIStmt *stmt;
OCIHandleAlloc(env, (void **)&stmt, OCI_HTYPE_STMT, 0, NULL);
OCIStmtPrepare(stmt, err, (text *) sql, strlen(sql), OCI_NTV_SYNTAX, OCI_DEFAULT);
if (OCIBindByPos(stmt, &bnd, err, 1, (void *)&image_id, sizeof(image_id), SQLT_INT, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT) != OCI_SUCCESS)
{
printf(“Fled to bind image_id!\n”);
return -1;
}
if (OCIBindByPos(stmt, &bnd, err, 2, (void *)image_name, strlen(image_name), SQLT_STR, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT) != OCI_SUCCESS)
{
printf(“Fled to bind image_name!\n”);
return -1;
}
if (OCIBindByPos(stmt, &bnd, err, 3, (void *)blob, -1, SQLT_BLOB, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT) != OCI_SUCCESS)
{
printf(“Fled to bind image_data!\n”);
return -1;
}
// Insert image data into database
OCILOBCreate(svc, err, &blob, OCI_TEMP_BLOB, OCI_DEFAULT);
OCILOBWrite(svc, err, blob, image_data, image_size, OCI_DEFAULT);
// Execute SQL statement
OCIStmtExecute(svc, stmt, err, 1, 0, NULL, NULL, OCI_DEFAULT);
// Free resources
OCIHandleFree((void *)blob, OCI_HTYPE_LOB);
OCIHandleFree((void *)svc, OCI_HTYPE_SVCCTX);
OCIHandleFree((void *)err, OCI_HTYPE_ERROR);
OCIHandleFree((void *)env, OCI_HTYPE_ENV);
return 0;
}
步骤4:从 Oracle 数据库中检索图片
在许多情况下,需要从 Oracle 数据库中检索图片并将其显示。以下是一个从 Oracle 数据库中检索图片和将其显示的示例:
#include
#include
#include
#include
int mn(void)
{
OCIEnv *env;
OCIError *err;
OCISvcCtx *svc;
OCILobLocator *blob;
char *image_data;
int image_size;
char *sql;
int image_id;
// Connect to Oracle database
if (OCIHandleAlloc(env, (void **)&svc, OCI_HTYPE_SVCCTX, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate service context handle!\n”);
return -1;
}
if (OCIHandleAlloc(env, (void **)&err, OCI_HTYPE_ERROR, 0, NULL) != OCI_SUCCESS)
{
printf(“Fled to allocate error handle!\n”);
return -1;
}
OCIEnvCreate(&env, OCI_DEFAULT, NULL, NULL, NULL, NULL, 0, NULL);
ociinitialize(OCI_THREADED|OCI_OBJECT, NULL, NULL, NULL, NULL);
// Prepare SQL statement
sql = “SELECT image_data FROM images WHERE image_id = :1”;
OCIStmt *stmt;
OCIHandleAlloc(env, (void **)&stmt, OCI_HTYPE_STMT, 0, NULL);
OCIStmtPrepare(stmt, err, (text *) sql, strlen(sql), OCI_NTV_SYNTAX, OCI_DEFAULT);
if (OCIBindByPos(stmt, &bnd, err, 1, (void *)&image_id, sizeof(image_id), SQLT_INT, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT) != OCI_SUCCESS)
{
printf(“Fled to bind image_id!\n”);
return -1;
}
// Execute SQL statement
OCIStmtExecute(svc, stmt, err, 1, 0, NULL, NULL, OCI_DEFAULT);
//