在set中已经 存在，返回<x在set中的位置，false>

在元素访问时，有一个与operator[]类似的操作at()(该函数不常用)函数，都是通过key找到与key对应的value然后返回其引用，不同的是：当key不存在时，operator[]用默认value与key构造键值对然后插入，返回该默认value,at()函数则是直接抛异常。

map中元素的操作

当key已存在时，insert插入失败 [] 支持 查找，插入，修改

【总结】

1. map中的的元素是键值对
2. map中的key是唯一的，并且不能修改
3. 默认按照小于的方式对key进行比较
4. map中的元素如果用迭代器去遍历，可以得到一个有序的序列
5. map的底层为平衡搜索树(红黑树)，查找效率比较高$O(log_2 N)$
6. 支持[]操作符，operator[]中实际进行插入查找。#include <set>

void TestSet()

{

 int array[] = { 2, 1, 3, 9, 6, 0, 5, 8, 4, 7 };

// 注意：multiset在底层实际存储的是<int, int>的键值对

multiset<int> s(array, array + sizeof(array)/sizeof(array[0]));

for (auto& e : s)

cout << e << " ";

cout << endl;

return 0;

}

@Data

@AllArgsConstructor

@Slf4j

public class AliOssUtil {

private String endpoint;

private String accessKeyId;

private String accessKeySecret;

private www.laipuhuo.com String bucketName;

/**

* 文件上传

*

* @param bytes

* @param objectName

* @return

*/

public String upload(byte[] bytes, String objectName) {

// 创建OSSClient实例。

OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);

try {

// 创建PutObject请求。

ossClient.www.laipuhuo.com putObject(bucketName, objectName, new ByteArrayInputStream(bytes));

} catch (OSSException oe) {

System.out.println("Caught an OSSException, which means your request made it to OSS, "

+ "but was rejected with an error response for some reason.");

System.out.println("Error Message:" + oe.getErrorMessage());

System.out.println("Error Code:" + oe.getErrorCode());

System.out.println("Request ID:" + oe.getRequestId());

System.out.println("Host ID:" + oe.getHostId());

} catch (ClientException ce) {

System.out.println("Caught an ClientException, which means the client encountered "

+ "a www.laipuhuo.com serious internal problem while trying to communicate with OSS, "

+ "such as not being able to access the network.");

System.out.println("Error Message:" + ce.getMessage());

} finally {

if (ossClient != null) {

ossClient.shutdown();

}

}

//文件访问路径规则 https://BucketName.Endpoint/ObjectName

StringBuilder stringBuilder = new StringBuilder("https://");

stringBuilder

.append(bucketName)

.append(".")

.append(endpoint)

.append(www.laipuhuo.com"/")

.append(objectName);

log.info("文件上传到:{}", stringBuilder.toString());

return stringBuilder.toString();

}

}