Java study notes: MD5 Java message digest algorithm

The main feature of the message digest algorithm is encryption key is not necessary, and through the encrypted data cannot be decrypted, only input the same plaintext data through the same message digest algorithm to get the same ciphertext. A message digest algorithm does not exist in the management and distribution of the key, which is suitable for the same use in the distributed network. Due to the considerable amount of computation of its encryption, the previous algorithm is usually only used in the case of limited data, for example, the computer's password is encrypted with the non reversible encryption algorithm. * * * message digest algorithm MD * @desc...
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Java study notes: Java asymmetric encryption

The symmetric encryption algorithm is used in the encryption and decryption is the same secret key; and non symmetric encryption algorithm needs two keys for encryption and decryption, the two secret key is public key (public key (public key and private key (private key (private key). It is a kind of advanced double insurance encryption method, the general encryption method has DH key exchange algorithm, RSA based on factor decomposition algorithm, ElGamal discrete logarithm algorithm and ECC elliptic curve encryption and so on. ------------------DH encryption and decryption -...
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Java study notes: Java symmetric encryption

Symmetric encryption is the use of this encryption method of the two sides use the same key to encrypt and decrypt. Key is the instruction to control the process of encryption and decryption. Algorithm is a set of rules that specify how to encrypt and decrypt. Need to encrypt and decrypt the encryption algorithm using the same key. Due to its high speed, symmetry encryption usually need to encrypt the message sender when using large amounts of data. Symmetric encryption, also known as key encryption. Encryption security depends not only on the encryption algorithm itself, security key management is more important. Because both the encryption and decryption are using the same key, how to safely transfer the key to the decryption...
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Android study notes: to achieve the drop-down refresh of the ListView

Listview pull down to refresh and pull load more data we developed usually in order to achieve the function, the open source project has a lot of up and down loading refresh the listview can be directly used to use, the past few days just learning the refresh of the implementation, to record, to learn the information: The picture achieve simple effect: This is the drop-down display, text may be different. To return as a graph:. At this point, after the release of the hand, there is a circular progress bar loading state, after loading the completion of the HeaderView section (including the above image, and the load bar is hidden). ...
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Android study notes: BaseAdapter use the three realm

* The application of * adapter mode: * reduce coupling program * easy to expand * similiarly * listview caching mechanism: need to display, display after recycling to cache recycler, at the next show and from the cache taken out show * * . Class MainActivity extends Activity public...
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Android study notes: to create ListView (GridView), such as universal adapter Adapter

Show the list view, the GridView list controls are we in the project an integral part, and used in the project, certainly more than one or two places, good projects, large projects may use dozens or hundreds of listview. We know that to achieve listview loading data, you need to write the data adapter adapter to the listview. Usually, it is according to the demand, the listview is different for different adapter. The adapter needs extends BaseAdapte...
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Android study notes: Android message processing mechanism of Handler introduction

Handler introduction: 1, the handler is what: the handler is Android system used to update the main UI interface of an asynchronous operation mechanism and Android to receive messages, message processing a message processing mechanism. . in the Android why to use Handler:Android main thread (the UI thread) cannot perform time-consuming operations nor in the child thread directly update the UI information, in order to realize the information interaction between the main thread and thread, in order to solve the problem of interaction, Androi...
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Android study notes: Android update UI several commonly used methods

Android main thread cannot perform long-running operations, we are generally in subthreads perform long-running operations, we executed time-consuming operations, we can generally through the following several ways to realize UI updates: Xmlns:tools= "" Android:layout_width= "match_parent" Android:layout_height= "ma...
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