ClassLoader classification

For a total of three class loader,

1. 1 are under the Bootstrap loader loading rt package is written in C ++ and is written in java, when the first release for loading those initial class.
2. 2 then have to release a new java jdk in the development process, so in order to expand the new content of the jar package, the new javax directory are loaded by using Extension. This is written in java.
3. 3 Finally, programmers write their own programs to load, such as a person you write a class to be loaded on the need AppClassLoader loader loads.