ajax同步异步的区别（The difference between Ajax synchronous asynchronous）.doc

ajax同步异步的区别（The difference between Ajax synchronous asynchronous） 1.ajax synchronous and asynchronous For example: ordinary B/S mode (synchronous) AJAX Technology (asynchronous) Synchronization: submit the request - wait for the server processing GT processed during the return to the client browser can not do anything Asynchronous request processing server through event trigger (- this is a browser can still do other things) - processed The synchronization is when you ask me to eat, I hear you go to dinner with you, if not heard, you will not stop calling, until I tell you to hear, and then go to dinner together. Asynchronous is you call me, and then go to eat, I may go immediately after the news, may also wait until after work to eat. So, if you want me to treat you to a meal, you can use a synchronous method and ask me to have a meal with an asynchronous method so that you can save money. For example, when calling, synchronous messages are asynchronous Look at a few parameters of the open method. .open (http-method, URL, async, userID, password) (followed by an account number and password, user name and password are required in the anonymous anonymous HTTP page) First look at asynchronous processing. Where async is a Boolean value. If it is asynchronous communication (true), the client does not wait for the server to respond; if it is synchronous (false), the client waits until the server returns the message to perform other operations. We need to specify synchronization mode according to the actual need, on some pages, may issue multiple requests, and even organized and planned a large-scale formation of high strength request, then one will overwrite the previous one, of course, this time to specify synchronization mode: Flase. The use of PreparedStatement API, one of the four main classes in the JDBC (Java, database, connectivity, Java database connections) java.sql.statement, requires developers to spend a lot of time and effort. One common problem with usin