C语言实现Oracle数据库中存储图像的方法（c oracle 存图像）

C语言实现Oracle数据库中存储图像的方法

在实际开发中，我们经常需要对图像进行处理和存储。而Oracle数据库是一个功能强大的关系数据库管理系统，其支持图像存储和处理功能，可以在Oracle数据库中存储所有类型的图像，并通过C语言来实现图像存储操作。

1. 通过C语言连接Oracle数据库

在实现图像存储的过程中，需要用到C语言连接Oracle数据库。我们可以使用Oracle提供的OCI接口（Oracle Call Interface）来实现与Oracle数据库的通信和操作。

以下示例代码演示如何连接Oracle数据库：

“`c

#include

#include

#include

int mn(void) {

OCIEnv *envhp;

OCIError *errhp;

OCISvcCtx *svchp;

OCIStmt *stmthp;

OCIInitialize(OCI_DEFAULT, NULL, NULL, NULL, NULL);

OCIHandleAlloc((dvoid *)NULL, (dvoid **)&envhp, OCI_HTYPE_ENV, 0, (dvoid **)NULL);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, 0, (dvoid **)NULL);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&svchp, OCI_HTYPE_SVCCTX, 0, (void **)NULL);

OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)svchp, 0, OCI_ATTR_SERVER, (OCIError *)errhp);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&stmthp, OCI_HTYPE_STMT, 0, (void **)NULL);

/* 开始连接数据库 */

OCILogon(envhp, errhp, &svchp, “username”, strlen(“username”), “password”, strlen(“password”), “dbname”, strlen(“dbname”));

/* 执行SQL语句 */

OCIStmtPrepare(stmthp, errhp, “SELECT * FROM tablename”, strlen(“SELECT * FROM tablename”), OCI_NTV_SYNTAX, OCI_DEFAULT);

return 0;

}

2. 存储图像数据到Oracle数据库

在连接数据库成功后，我们就可以开始实现图像存储操作了。Oracle数据库提供了大对象（LOB）类型，可以用来存储大量的二进制数据，包括图像数据。

以下示例代码演示如何在C程序中存储一张图像到Oracle数据库中：

```c

#include 
#include 
#include 
int mn(void) {
    OCIEnv *envhp;
    OCIError *errhp;
    OCISvcCtx *svchp;
    OCIStmt *stmthp;
    OCILobLocator *lob;
    FILE *fp;
    char *data;
    int size;
    int ret;
    OCIInitialize(OCI_DEFAULT, NULL, NULL, NULL, NULL);

    OCIHandleAlloc((dvoid *)NULL, (dvoid **)&envhp, OCI_HTYPE_ENV, 0, (dvoid **)NULL);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, 0, (dvoid **)NULL);
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&svchp, OCI_HTYPE_SVCCTX, 0, (void **)NULL);

    OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)svchp, 0, OCI_ATTR_SERVER, (OCIError *)errhp);

    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&stmthp, OCI_HTYPE_STMT, 0, (void **)NULL);

    /* 开始连接数据库 */
    OCILogon(envhp, errhp, &svchp, "username", strlen("username"), "password", strlen("password"), "dbname", strlen("dbname"));
    /* 打开图像文件 */
    fp = fopen("image.jpg", "rb");
    /* 获取文件大小 */
    fseek(fp, 0, SEEK_END);
    size = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    /* 分配内存 */
    data = malloc(size);
    /* 读取图像数据 */
    fread(data, 1, size, fp);
    /* 分配LOB对象 */
    OCIHandleAlloc((dvoid *)envhp, (dvoid **)&lob, OCI_DTYPE_LOB, 0, (dvoid **)NULL);
    /* 插入数据 */
    OCIStmtPrepare(stmthp, errhp, "INSERT INTO tablename (id, image) VALUES (?, empty_blob())", strlen("INSERT INTO tablename (id, image) VALUES (?, empty_blob())"), OCI_NTV_SYNTAX, OCI_DEFAULT);
    OCIDefineByPos(stmthp, &lob, errhp, 2, sizeof(OCILobLocator *), SQLT_BLOB, NULL, NULL, NULL, OCI_DEFAULT);

    /* 提交事务 */
    ret = OCIStmtExecute(svchp, stmthp, errhp, 1, 0, NULL, NULL, OCI_COMMIT_ON_SUCCESS);
    /* 保存LOB对象 */
    OCILobLocator *tempLob = NULL;
    if (OCIDescriptorAlloc(envhp, (void**) &tempLob, OCI_DTYPE_LOB, 0, NULL) == OCI_SUCCESS) {
        char selectLob[] = "SELECT image FROM tablename WHERE id = 1 FOR UPDATE";
        OCIStmt* selstmthp;
        ret = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&selstmthp, OCI_HTYPE_STMT, 0, (dvoid **)NULL);
        OCIStmtPrepare(selstmthp, errhp, selectLob, strlen(selectLob), OCI_NTV_SYNTAX, OCI_DEFAULT);
        OCIStmtExecute(svchp, selstmthp, errhp, 1, 0, NULL, NULL, OCI_DEFAULT);
        OCIDefineByPos(selstmthp, &tempLob, errhp, 1, 0, SQLT_BLOB, 0,0,0,OCI_DEFAULT);
        if (OCILOBAssign(envhp, errhp, lob, &tempLob) == OCI_SUCCESS) {
            OCILobLocatorIsNull(envhp, errhp, tempLob, &ret);
            if (ret != TRUE) {
                if (OCILOBTrim(envhp, errhp, lob, -1) == OCI_SUCCESS) {
                    ub4 amtp = 0;
                    if (OCILobWrite(svchp, errhp, lob, &amtp, 1, data, size, OCI_ONE_PIECE, NULL, NULL, SQLCS_IMPLICIT)) {
                        fprintf(stderr, "OCILobWrite fled\n");
                        const char* errMsg = NULL;
                        ub4 msgLen = 0;
                        OCIErrorGet(errhp, 1, NULL, &errMsg, &msgLen);
                        fprintf(stderr, "ERROR:%s\n", errMsg);
                        return 1;
                    }
                }
            }
        }
    }
    OCILogoff(svchp, errhp);
    OCIHandleFree((dvoid *)envhp, OCI_HTYPE_ENV);
    OCIHandleFree((dvoid *)errhp, OCI_HTYPE_ERROR);
    OCIHandleFree((dvoid *)svchp, OCI_HTYPE_SVCCTX);
    OCIHandleFree((dvoid *)stmthp, OCI_HTYPE_STMT);
    free(data);
    fclose(fp);

    return 0;
}

3. 从Oracle数据库中读取图像数据

通过C语言连接Oracle数据库，并成功存储了一张图像后，我们可以通过C语言实现从Oracle数据库中读取图像数据。

以下示例代码演示如何在C程序中从Oracle数据库中读取一张图像：

“`c

#include

#include

#include

int mn(void) {

OCIEnv *envhp;

OCIError *errhp;

OCISvcCtx *svchp;

OCIStmt *stmthp;

OCILobLocator *lob;

FILE *fp;

char *data;

int size;

int ret;

OCIInitialize(OCI_DEFAULT, NULL, NULL, NULL, NULL);

OCIHandleAlloc((dvoid *)NULL, (dvoid **)&envhp, OCI_HTYPE_ENV, 0, (dvoid **)NULL);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, 0, (dvoid **)NULL);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&svchp, OCI_HTYPE_SVCCTX, 0, (void **)NULL);

OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)svchp, 0, OCI_ATTR_SERVER, (OCIError *)errhp);

OCIHandleAlloc((dvoid *)envhp, (dvoid **)&stmthp, OCI_HTYPE_STMT, 0, (void **)NULL);

/* 开始连接数据库 */

OCILogon(envhp, errhp, &svchp, “username”,